There has been a striking decline in the number of large sharks caught off Queensland’s coast over the past 50 years, suggesting that populations have declined dramatically.
Our study, published today in the journal Communications Biology, used historical data from the Queensland Shark Control Program.
Catch numbers of large apex sharks (hammerheads, tigers and white sharks) declined by 74-92%, and the chance of catching no sharks at any given beach per year has increased by as much as seven-fold.
Coinciding with ongoing declines in numbers of sharks in nets and drum lines, the probability of recording mature male and females has declined over the past two decades.
Our discovery is at odds with recent media reports of “booming” shark numbers reaching “plague” along our coastlines. The problem with those claims is that we previously had little idea of what the “natural” historical shark population would have been.
Why is the decline of sharks on the Queensland coastline a cause for concern? Large apex sharks have unique roles in coastal ecosystems, preying on weak and injured turtles, dolphins and dugongs, actively scavenging on dead whale carcasses, and connecting coral reefs, seagrass beds and coastal ecosystems.
As a nation, Australia has a long history with sharks. Some of the oldest stories in the world were written by the indigenous Yanyuwa people in the Northern Territory some 40,000 years ago, describing how the landscape of their coastal homeland was created by tiger sharks.
European settlers in the late 18th and early 19th centuries further described Australian coastlines as being “chock-full of sharks”, and upon visiting Sydney in 1895, the US author Mark Twain remarked:
The government pays a bounty of the shark; to get the bounty the fishermen bait the hook or the seine with agreeable mutton; the news spreads and the sharks come from all over the Pacific Ocean to get the free board. In time the shark culture will be one of the most successful things in the colony.
With the rise of Australian beach and surf culture, and the growing population density in coastal communities in the mid-20th century, increasing numbers of unprovoked fatal encounters with sharks occurred along the Queensland and New South Wales coastlines.
White sharks were extensively targeted and killed in “game fishing” tournaments, and harmless grey nurse sharks were hunted almost to extinction through recreational spearfishing in the 1950s and 1960s.
Yet despite this long history of shark exploitation, the historical baseline populations of sharks off Australia’s east coast were largely unknown.
Through mesh nets and baited drumlines, the Queensland Shark Control Program targets large sharks, with the aim of reducing local populations and minimise encounters between sharks and humans. Records of shark catches dating back as far as the 1960s provide a unique window into the past on Queensland beaches.
While we will never know exactly how many sharks roamed these waters more than half a century ago, the data points to radical changes in our coastal ecosystems since the 1960s.
The exact causes of declining shark numbers are difficult to pinpoint, largely because of a lack of detailed records from commercial or recreational fisheries before the 2000s. The Queensland government also acknowledges that the program itself has a direct impact on shark populations by selectively removing large, reproductively mature sharks from the population.
The data indicates that two hammerhead species – the scalloped and great hammerheads, both of which are listed as globally endangered – have declined by as much as 92% in Queensland over the past half century.
Similarly, the once-abundant white sharks have also shown no sign of recovery, despite a complete ban on commercial and recreational fishing in Queensland, implemented more than two decades ago.
The idea that shark populations are reaching “plague” proportions in recent years may represent a classic case of shifting baseline syndrome. Using shark numbers from recent history as a baseline may give a false perception that populations are “exploding”, whereas records from fifty years ago indicate that present day numbers are a fraction of what they once were.
Our results indicate that large shark species are becoming increasingly rare along Australia’s coastline. We should not be concerned about a “plague” of sharks, but rather the opposite: the fact that previously abundant apex shark species are increasingly at risk.
14 December 2018
The Antarctic Circumpolar Current, or ACC, is the strongest ocean current on our planet. It extends from the sea surface to the bottom of the ocean, and encircles Antarctica.
It is vital for Earth’s health because it keeps Antarctica cool and frozen. It is also changing as the world’s climate warms. Scientists like us are studying the current to find out how it might affect the future of Antarctica’s ice sheets, and the world’s sea levels.
The ACC carries an estimated 165 million to 182 million cubic metres of water every second (a unit also called a “Sverdrup”) from west to east, more than 100 times the flow of all the rivers on Earth. It provides the main connection between the Indian, Pacific and Atlantic Oceans.
The tightest geographical constriction through which the current flows is Drake Passage, where only 800 km separates South America from Antarctica. While elsewhere the ACC appears to have a broad domain, it must also navigate steep undersea mountains that constrain its path and steer it north and south across the Southern Ocean.
A satellite view over Antarctica reveals a frozen continent surrounded by icy waters. Moving northward, away from Antarctica, the water temperatures rise slowly at first and then rapidly across a sharp gradient. It is the ACC that maintains this boundary.
The ACC is created by the combined effects of strong westerly winds across the Southern Ocean, and the big change in surface temperatures between the Equator and the poles.
Ocean density increases as water gets colder and as it gets more salty. The warm, salty surface waters of the subtropics are much lighter than the cold, fresher waters close to Antarctica. We can imagine that the depth of constant density levels slopes up towards Antarctica.
The westerly winds make this slope steeper, and the ACC rides eastward along it, faster where the slope is steeper, and weaker where it’s flatter.
In the ACC there are sharp changes in water density known as fronts. The Subantarctic Front to the north and Polar Front further south are the two main fronts of the ACC (the black lines in the images). Both are known to split into two or three branches in some parts of the Southern Ocean, and merge together in other parts.
Scientists can figure out the density and speed of the current by measuring the ocean’s height, using altimeters. For instance, denser waters sit lower and lighter waters stand taller, and differences between the height of the sea surface give the speed of the current.
The path of the ACC is a meandering one, because of the steering effect of the sea floor, and also because of instabilities in the current.
The ACC also plays a part in the meridional (or global) overturning circulation, which brings deep waters formed in the North Atlantic southward into the Southern Ocean. Once there it becomes known as Circumpolar Deep Water, and is carried around Antarctica by the ACC. It slowly rises toward the surface south of the Polar Front.
Once it surfaces, some of the water flows northward again and sinks north of the Subarctic Front. The remaining part flows toward Antarctica where it is transformed into the densest water in the ocean, sinking to the sea floor and flowing northward in the abyss as Antarctic Bottom Water. These pathways are the main way that the oceans absorb heat and carbon dioxide and sequester it in the deep ocean.
The ACC is not immune to climate change. The Southern Ocean has warmed and freshened in the upper 2,000 m. Rapid warming and freshening has also been found in the Antarctic Bottom Water, the deepest layer of the ocean.
Waters south of the Polar Front are becoming fresher due to increased rainfall there, and waters to the north of the Polar Front are becoming saltier due to increased evaporation. These changes are caused by human activity, primarily through adding greenhouse gases to the atmosphere, and depletion of the ozone layer. The ozone hole is now recovering but greenhouse gases continue to rise globally.
Winds have strengthened by about 40% over the Southern Ocean over the past 40 years. Surprisingly, this has not translated into an increase in the strength of the ACC. Instead there has been an increase in eddies that move heat towards the pole, particularly in hotspots such as Drake Passage, Kerguelen Plateau, and between Tasmania and New Zealand.
We have observed much change already. The question now is how this increased transfer of heat across the ACC will impact the stability of the Antarctic ice sheet, and consequently the rate of global sea-level rise.
Helen Phillips, Senior Research Fellow, Institute for Marine and Antarctic Studies, University of Tasmania; Benoit Legresy, , CSIRO, and Nathan Bindoff, Professor of Physical Oceanography, Institute for Marine and Antarctic Studies, University of Tasmania
The lost world was uncovered during detailed seafloor mapping by CSIRO research vessel Investigator while on a 25-day research voyage led by scientists from the Australian National University (ANU). The mapping has revealed, for the first time, a diverse chain of volcanic seamounts located in deep water about 400 km east of Tasmania. The seamounts tower up to 3000 m from the surrounding seafloor but the highest peaks are still far beneath the waves, at nearly 2000 m below the surface. Dr Tara Martin, from the CSIRO mapping team, said the mapping offered a window into a previously unseen and spectacular underwater world.
“Our multibeam mapping has revealed in vibrant detail, for the first time, a chain of volcanic seamounts rising up from an abyssal plain about 5000m deep, Dr Martin said. "The seamounts vary in size and shape, with some having sharp peaks while others have wide flat plateaus, dotted with small conical hills that would have been formed by ancient volcanic activity. “Having detailed maps of such areas is important to help us better manage and protect these unique marine environments, and provides a stepping stone for future research.
“This is a very diverse landscape and will undoubtedly be a biological hotspot that supports a dazzling array of marine life,” she said. Ship data collected during the voyage revealed spikes in ocean productivity over the chain of seamounts, with increased phytoplankton activity and marine animal observations in the area.
Dr Eric Woehler from BirdLife Tasmania, who was on Investigator with a team conducting seabird and marine mammal surveys, was astounded by the amount of life they saw above the seamounts.
“While we were over the chain of seamounts, the ship was visited by large numbers of humpback and long-finned pilot whales,” Dr Woehler said. “We estimated that at least 28 individual humpback whales visited us on one day, followed by a pod of 60-80 long-finned pilot whales the next. We also saw large numbers of seabirds in the area including four species of albatross and four species of petrel.”
“Clearly, these seamounts are a biological hotspot that supports life, both directly on them, as well as in the ocean above,” he said.
Research indicates that seamounts may be vital stopping points for some migratory animals, especially whales. Whales may use these seafloor features as navigational aids during their migration. “These seamounts may act as an important signpost on an underwater migratory highway for the humpback whales we saw moving from their winter breeding to summer feeding grounds,” Dr Woehler said. “Lucky for us and our research, we parked right on top of this highway of marine life!” The life and origin of the seamounts will be further studied later this year when Investigator returns to the region for two further research voyages departing in November and December. A range of surveys will be conducted on these voyages, including capturing high resolution video of marine life on the seamounts using deep water cameras, and collecting rock samples to better understand their formation and origin. Dr Woehler will be on the first of these voyages and expects further surprises on the return visit. “We expect that these seamounts will be a biological hotspot year round, and the summer visit will give us another opportunity to uncover the mysteries of the marine life they support,” said Dr Woehler.
Research vessel Investigator is Australia’s only research vessel dedicated to blue-water research, and is owned and operated by CSIRO – Australia’s national science agency. The vessel conducts research year round, and is made available to Australian researchers and their international collaborators.
11 October 2018, First published by CSIRO, at: https://www.csiro.au/en/News/News-releases/2018/Scientists-uncover-volcanic-lost-world
Four tiger sharks have now been captured and killed following two separate attacks off the coast of North Queensland last week. Despite being relatively rare, shark attacks – or the threat of attacks – not only disrupt recreational beach activities, but can affect associated tourist industries.
Shark nets are a common solution to preventing shark attacks on Australian beaches, but they pose dangers to marine ecosystems.
Seeking a cost-effective way to monitor beach safety over large areas, we have developed a system called SharkSpotter. It combines artificial intelligence (AI), computing power, and drone technology to identify and alert lifesavers to sharks near swimmers.
SharkSpotter was named the national AI or Machine Learning Innovation of the Year at the Australian Information industry Association (AIIA) annual iAwards this month.
The project is a collaboration between the University of Technology Sydney and The Ripper Group, which is pioneering the use of drones – called “Westpac Little Ripper Lifesavers” – in the search and rescue movement in Australia.
SharkSpotter can detect sharks and other potential threats using real-time aerial imagery. The system analyses streaming video from a camera attached to a drone (an unmanned aerial vehicle, or UAV) to monitor beaches for sharks, issue alerts, and conduct rescues.
Developed using machine learning techniques known as “deep learning”, the SharkSpotter system receives streaming imagery from the drone camera and attempts to identify all objects in the scene. Once valid objects are detected, they are put into one of 16 categories: shark, whale, dolphin, rays, different types of boats, surfers, and swimmers.
If a shark is detected, SharkSpotter provides both a visual indication on the computer screen and an audible alert to the operator. The operator verifies the alert and sends text messages from the SharkSpotter system to the Surf Life Savers for further action.
In an emergency, the drone is equipped with a lifesaving flotation pod together with an electronic shark repellent that can be dropped into the water in cases where swimmers are in severe distress, trapped in a rip, or if there are sharks close by.
The development of SharkSpotter involved several stages.
Among the most time-consuming tasks was collecting and annotating the necessary data. The data were collected by The Ripper Group by flying a drone with a camera attached to it above different Australian beaches.
We then manually annotated each video to indicate the specific location of sharks and other objects. The video frames and the annotations were then used to train the deep learning algorithm to correctly identify and classify objects.
These advanced machine learning techniques significantly improve aerial detection to more than 90% accuracy. That’s much better than conventional techniques such as helicopters with human spotters (17.1%) and fixed-wing aircraft spotters (12.5%).
We tested the system at different Australian beaches to determine the varying parameters, such as camera resolution, height above sea level (which can affect the vision clarity of drones), speed and flight duration.
After successful trials and fine-tuning of the system, SharkSpotter was used across a dozen popular beaches in New South Wales and Queensland last summer.
The system was developed to help Surf Life Savers monitor the beach more effectively – as opposed to replacing them – and has been received positively by end-users and communities alike, according to a survey conducted by The Ripper Group.
In January 2018, the Westpac Little Ripper Lifesaver was used to rescue two young swimmers caught in a rip at Lennox Head, NSW.
The drone flew down the beach some 800 metres from the lifeguard station, and a lifesaving flotation pod was dropped from the drone. The complete rescue operation took 70 seconds.
We believe SharkSpotter is a win-win for both marine life and beachgoers. From a technology perspective, it has demonstrated how to detect moving objects in a complex, dynamic marine environment from a fast-moving drone.
This unique technology combines dynamic video image processing AI and advanced drone technology to creatively address the global challenge of ensuring safe beaches, protecting marine environments, and enhancing tourism.
The authors would like to acknowledge the contributions of Dr Paul Scully Power, co-founder of The Ripper Group, who partnered in the development of SharkSpotter.
Nabin Sharma, Senior Lecturer, UTS School of Software, University of Technology Sydney and Michael Blumenstein, Associate Dean Research (Strategy and Management) at the University of Technology Sydney, University of Technology Sydney
This article is republished from The Conversation under a Creative Commons license.
28 September 2018
It’s stunning but true that we know more about the surface of the moon than about the Earth’s ocean floor. Much of what we do know has come from scientific ocean drilling – the systematic collection of core samples from the deep seabed. This revolutionary process began 50 years ago, when the drilling vessel Glomar Challenger sailed into the Gulf of Mexico on August 11, 1968 on the first expedition of the federally funded Deep Sea Drilling Project.
I went on my first scientific ocean drilling expedition in 1980, and since then have participated in six more expeditions to locations including the far North Atlantic and Antaractica’s Weddell Sea. In my lab, my students and I work with core samples from these expeditions. Each of these cores, which are cylinders 31 feet long and 3 inches wide, is like a book whose information is waiting to be translated into words. Holding a newly opened core, filled with rocks and sediment from the Earth’s ocean floor, is like opening a rare treasure chest that records the passage of time in Earth’s history.
Over a half-century, scientific ocean drilling has proved the theory of plate tectonics, created the field of paleoceanography and redefined how we view life on Earth by revealing an enormous variety and volume of life in the deep marine biosphere. And much more remains to be learned.
Two key innovations made it possible for research ships to take core samples from precise locations in the deep oceans. The first, known as dynamic positioning, enables a 471-foot ship to stay fixed in place while drilling and recovering cores, one on top of the next, often in over 12,000 feet of water.
Anchoring isn’t feasible at these depths. Instead, technicians drop a torpedo-shaped instrument called a transponder over the side. A device called a transducer, mounted on the ship’s hull, sends an acoustic signal to the transponder, which replies. Computers on board calculate the distance and angle of this communication. Thrusters on the ship’s hull maneuver the vessel to stay in exactly the same location, countering the forces of currents, wind and waves.
Another challenge arises when drill bits have to be replaced mid-operation. The ocean’s crust is composed of igneous rock that wears bits down long before the desired depth is reached.
When this happens, the drill crew brings the entire drill pipe to the surface, mounts a new drill bit and returns to the same hole. This requires guiding the pipe into a funnel shaped re-entry cone, less than 15 feet wide, placed in the bottom of the ocean at the mouth of the drilling hole. The process, which was first accomplished in 1970, is like lowering a long strand of spaghetti into a quarter-inch-wide funnel at the deep end of an Olympic swimming pool.
When scientific ocean drilling began in 1968, the theory of plate tectonics was a subject of active debate. One key idea was that new ocean crust was created at ridges in the seafloor, where oceanic plates moved away from each other and magma from earth’s interior welled up between them. According to this theory, crust should be new material at the crest of ocean ridges, and its age should increase with distance from the crest.
The only way to prove this was by analyzing sediment and rock cores. In the winter of 1968-1969, the Glomar Challenger drilled seven sites in the South Atlantic Ocean to the east and west of the Mid-Atlantic ridge. Both the igneous rocks of the ocean floor and overlying sediments aged in perfect agreement with the predictions, confirming that ocean crust was forming at the ridges and plate tectonics was correct.
The ocean record of Earth’s history is more continuous than geologic formations on land, where erosion and redeposition by wind, water and ice can disrupt the record. In most ocean locations sediment is laid down particle by particle, microfossil by microfossil, and remains in place, eventually succumbing to pressure and turning into rock.
Microfossils (plankton) preserved in sediment are beautiful and informative, even though some are smaller than the width of a human hair. Like larger plant and animal fossils, scientists can use these delicate structures of calcium and silicon to reconstruct past environments.
Thanks to scientific ocean drilling, we know that after an asteroid strike killed all non-avian dinosaurs 66 million years ago, new life colonized the crater rim within years, and within 30,000 years a full ecosystem was thriving. A few deep ocean organisms lived right through the meteorite impact.
Ocean drilling has also shown that ten million years later, a massive discharge of carbon – probably from extensive volcanic activity and methane released from melting methane hydrates – caused an abrupt, intense warming event, or hyperthermal, called the Paleocene-Eocene Thermal Maximum. During this episode, even the Arctic reached over 73 degrees Fahrenheit.
The resulting acidification of the ocean from the release of carbon into the atmosphere and ocean caused massive dissolution and change in the deep ocean ecosystem.
This episode is an impressive example of the impact of rapid climate warming. The total amount of carbon released during the PETM is estimated to be about equal to the amount that humans will release if we burn all of Earth’s fossil fuel reserves. Yet, an important difference is that the carbon released by the volcanoes and hydrates was at a much slower rate than we are currently releasing fossil fuel. Thus we can expect even more dramatic climate and ecosystem changes unless we stop emitting carbon.
Scientific ocean drilling has also shown that there are roughly as many cells in marine sediment as in the ocean or in soil. Expeditions have found life in sediments at depths over 8000 feet; in seabed deposits that are 86 million years old; and at temperatures above 140 degrees Fahrenheit.
Today scientists from 23 nations are proposing and conducting research through the International Ocean Discovery Program, which uses scientific ocean drilling to recover data from seafloor sediments and rocks and to monitor environments under the ocean floor. Coring is producing new information about plate tectonics, such as the complexities of ocean crust formation, and the diversity of life in the deep oceans.
This research is expensive, and technologically and intellectually intense. But only by exploring the deep sea can we recover the treasures it holds and better understand its beauty and complexity.
This article is republished from The Conversation under a Creative Commons license.
26 September 2018
Researchers at the Australian Institute of Marine Science have made a significant breakthrough in the war against crown-of-thorns starfish, on the Great Barrier Reef.
AIMS’ senior research leader Dr Sven Uthicke and biochemist Jason Doyle, along with echinoderm expert Dr Miles Lamare from the University of Otago, in New Zealand, have developed a cost effective method for detecting DNA of the coral-eating pest.
Dr Uthicke said the method would improve monitoring and early detection of the reef pest, also known as crown-of-thorns seastar, allowing reef managers to contain outbreaks sooner.
“It’s a genetic probe which we had developed to detect seastar larvae in plankton and we have been able to modify the method,” Dr Uthicke said. “We have worked on this for the past three years, and we have been able to adapt this to make it more sensitive to detect adult crown-of-thorns seastar.” Ecological monitoring has so far failed to detect early stages of an outbreak which has prevented timely intervention.
Dr Uthicke said the current method for detecting outbreaks were on-reef field surveys using divers but by the time these methods detect outbreaks, the outbreak is usually well established. “Standard monitoring techniques only identify about 5 per cent of the pest on reefs, but this new method will allow us to clearly identify whether greater numbers are present,” Dr Uthicke said. “It counts the number of gene copies in the sample of seawater from a reef using a novel technique called digital droplet PCR.”
During recent field work, using the probe on 11 reefs of the Great Barrier Reef, crown-of-thorns starfish DNA was detectable on those suffering outbreaks. In contrast, crown-of-thorns starfish DNA was absent from ‘post-outbreak’ reefs after populations collapsed, and from ‘pre-outbreak’ reefs.
The fourth wave of outbreaks since the 1960s started around 2010 on Australia’s far northern Great Barrier Reef and has seen the significant loss of coral cover to the voracious appetite of the starfish, making it a major contributor to the coral reef crisis. This outbreak has spread as far south as Townsville along the Great Barrier Reefs, and is expected to continue south. This research project was partly funded by The National Environmental Science Program (NESP), the Great Barrier Reef Marine Park Authority and philanthropist Ian Potter Foundation.
The paper ‘eDNA detection of corallivorous seastar (Acanthaster cf. solaris) outbreaks on the Great Barrier Reef using digital droplet PCR’ is available online in the journal Coral Reefs.
18 September 2018, Australian Institute of Marine Science, 2018
The whale shark is the largest fish in the world, but much of its lifecycle remains shrouded in mystery. These gentle giants gather in just a handful of places around the globe – something which has long baffled scientists – but our new research has started to explain why. Better understanding of whale shark movements could help prevent further population loss in a species that has already experienced a 63% population decline over the past 75 years.
When swimming solo, the whale shark, which can grow up to 18.8 metres in length and 34 tons in weight, travels all over the world. Recently, a group of scientists tracked the remarkable journey of one whale shark across the Pacific from Panama to the Philippines. At more than 12,000 miles it proved to be one of the longest migrations ever recorded.
Yet whale sharks are known to come together at just a few specific locations around the world. Anything from ten to 500 whale sharks may gather at any one time in areas off the coasts of Australia, Belize, the Maldives, Mexico and more.
Approximately 20 hotspots have been identified – mere pinpricks in the vastness of the world’s oceans – but we don’t know what exactly attracts the whale sharks to them. In some cases the sites are linked to a specific biological phenomenon – such as the spawning of land crabs at Christmas Island in the Indian Ocean, which provides whale sharks with the seasonal equivalent of a Christmas feast. Our new research aimed to discover whether there was something else that united the places where these giants of the ocean hang out.
The physical features of these spots – known as their bathymetry – have been shown to influence gathering points in other marine species. So in collaboration with the Maldives Whale Shark Research Programme, we decided to investigate whether it drives whale shark gatherings in the same way.
Our new global study shows that whale sharks congregate in specific areas of shallow water, next to steep slopes that quickly give way to areas much deeper water (usually between 200 metres and 1,000 metres).
We identified three main reasons. First, the deep water is used by whale sharks for feeding. Studies have shown the sharks diving to depths of almost 2 kilometres (1,928 metres to be precise) to feed on zooplankton and squid.
Second, the steep slopes are known to bring nutrients up to the surface from the deep, which in turn increases the abundance of plankton and attracts large numbers of filter feeding species. And finally, in shallow water, as well as feeding on coral and fish spawn, the sharks are able to thermoregulate, warming themselves back up after their dives into deep water which gets as cold as 4℃.
If you’ve ever seen or swum with a whale shark, it was most likely in one of these relatively shallow aggregation areas. Knowing where these hotspots are has provided local communities with a windfall from ecotourism. In the Maldives alone, economic benefits from whale shark-related activities were estimated at US$9.4m per year. Whale sharks are worth a lot more alive than dead – and with many of these meeting points in developing countries, the income is invaluable.
But with the increasing pressures of tourism comes new dangers for the sharks. Crowds of snorkelers and tourist vessels are increasingly disturbing the whale shark’s waters, and – more worryingly – risk potentially fatal strikes by boats. To protect these beautiful creatures and continue to reap the rewards of ecotourism, we recommend that marine protected areas should be set up around whale shark gatherings and codes of practice be followed when interacting with them.
These discoveries have narrowed down some of the key reasons why whale sharks congregate where they do, but many mysteries remain. Do individuals travel between these hotspots? Coastal gatherings are predominately made up of immature male sharks, usually still just four or five metres long. So where are all the girls? And where do whale sharks mate and give birth? Mating and pupping have never been seen in the wild – but, intriguingly, up to 90% of the whale sharks passing through the Galapagos marine reserve are female and thought to be pregnant.
Could this be a key labour ward for the world’s whale sharks? Last year a BBC film crew at the Galapagos attempted to follow a pregnant female in a submersible to watch it give birth, but to no avail. That’s one secret that the depths are keeping for now.
7 July 2018
Let’s look at the research.
The most reputable source for shark incident data in Australia is the Australian Shark Attack file, which is collated at Sydney’s Taronga Zoo.
The map below, created by The Conversation using data from the Australian Shark Attack File, shows incidents between sharks and humans in Australia between 1997 and 2017.
You can use the filter buttons in the map to explore the data by year, season, the type of injury, the type of shark involved, the type of incident – or a combination of all the filters. Press the ‘show all’ button to reset the search.
The number of recorded encounters between sharks and humans in Australia increased modestly between 1997 and 2017, but the reason for this is unclear. Over those two decades, the Australian population increased by 33%, but that alone doesn’t explain the increase in recorded shark encounters.
Correcting for the growth in human population in Australia, the data show that between 1997 and 2017:
Encounters between humans and sharks are extremely variable over time, and difficult to predict. The increases in recorded incidents between 1997 and 2017 are relatively small, and may be explained by factors not related to shark populations – such as increases in the reporting of shark encounters, or increasing beach use.
White Sharks (formerly Great White Sharks) are recorded as being responsible for 28 of the 36 fatal shark encounters in Australian waters between 1997 and 2017, and are the primary target of shark mitigation strategies of the Western Australian, New South Wales and Queensland governments.
So, has there been an increase in the number of White Sharks in Australian waters?
Estimating population numbers in the marine environment is difficult, especially for long-lived migratory species like White Sharks.
However, there is no evidence that White Sharks numbers are on the rise, either in Western Australia or along the Eastern coast. Despite targeted conservation efforts, the available research show stable or slightly declining numbers in these populations.
There are two distinct populations of White Sharks off Australian coasts – one to the west, and another to the east of Bass Strait, which separates Tasmania from mainland Australia. The eastern population includes New Zealand White Sharks.
Recent work by the CSIRO through the National Environmental Science Program’s Marine Biodiversity Hub using innovative DNA analysis has provided us with the most detailed and reliable estimates of population size we have for this species.
The CSIRO study shows there has been a slight decline in adult White Shark populations since the year 2000.
Current adult abundance for the eastern Australasian population is estimated at 750, with an uncertainty range of 470 to 1,030. The southern-western adult population is roughly double the size, estimated at 1,460, with an uncertainty range of 760 to 2,250.
Including the available information about juvenile White Sharks, estimates of total size for the eastern population in 2017 was 5,460, with an uncertainty range of 2,909 to 12,802.
It’s difficult to detect population trends with White Sharks because of the length of time it takes juveniles to reach maturity – around 15 years. As protection of White Sharks began in the late 1990s, any changes in abundance would only be starting to appear in current populations.
The traditional way of measuring shark and fish populations is by examining catches in commercial fisheries over long time periods. By correcting for the level of fishing effort – which is done by looking at things like the number of nets, hooks and tows deployed by fishermen – scientists can assume that changes in the “catchability” of sharks is related to their abundance.
But due to the relative rarity of catches of White Sharks by fishing vessels, this approach is less reliable for this species than the more recent genetic studies conducted by the CSIRO and outlined above.
Western Australia has a detailed measure of White Shark numbers assessed by catch data. A report published by the Western Australian Department of Fisheries in 2016 attempted to model changes in the southern-western Australian White Shark population since the late 1930s. The authors outlined four different plausible scenarios, none of which suggested a continuous increase in the number of White Sharks.
In New South Wales, there has been a cluster of shark bites in recent years. Data from the NSW Shark Meshing (Bather Protection) Program, managed by the NSW Department of Primary Industries, show a recent increase in White Sharks caught in nets placed near ocean beaches.
But when it comes to thinking about shark populations, we should not assume that these two facts are related. It’s important to remember that just because two things may correlate, it doesn’t mean that one caused the other.
These patterns could mean that the animals are coming closer to shore, rather than a population increase (or decrease).
A 2016 paper examined six global shark bite “hotspots” – the United States, South Africa, Australia, Brazil, Reunion Island and the Bahamas – and concluded that when it comes to encounters between sharks and humans, there are a range of causes at play.
The authors also noted that shark encounters appear to happen in clusters. For example, 2009 saw a spike in shark encounters off the New South Wales coast. This coincided with an increase in beach attendance and beach rescues during what was an unusually warm summer for south-east Australia.
A 2011 paper highlighted the popularity of water sports as a factor contributing to increased human-shark encounters. More people are taking part in water sports, and improvements in wetsuit technology mean that people are in the water for longer throughout the year.
However, there is limited information on the number of people who use Australian beaches, so this explanation needs to be further studied.
It’s vital that any strategies put in place to reduce the number of unprovoked encounters between humans and sharks in Australian waters are carefully considered, and based on the best available research.
27 February 2018
After several sightings of protected Humpback whales migrating along the east coast over the past two weeks, NSW Department of Primary Industries Minister Niall Blair has announced the second NSW North Coast net trial will come to an end.
NSW is also removing shark nets from their other 51 sites for the whale migration season. Whilst NSW is removing gear to prevent whale entanglements, Queensland continues at the peril of these majestic marine mammals. Please sign these petitions to demonstrate your support for marine animals.
Sea Shepherd welcomes the NSW Government announcement that ended the northern NSW shark net trial which was putting these ocean giants at too great a risk. Whale tourism is an important industry in Queensland with some of the finest whale watching tours available in centres from the Gold Coast to Hervey Bay and to Cairns and Port Douglas. Locals and tourists want to see these animals swimming freely without the risk of entanglement.
Sea Shepherd's Operation Apex Harmony team saw possibly 11 entanglements in Queensland Shark Control Program gear last year with a whale calf killed at Kurrawa in a shark net. Fellow campaigner and marine scientist, CEO of Humpbacks and Highrises, Dr Olaf Meynecke said: “Our organisation has long campaigned for the replacement of the shark nets in the Gold Coast as they are a major risk to protected marine life including whales who use the bay as a resting and calving ground each year.
"NSW has removed shark nets whilst only a few kilometres across the border in the Gold Coast bay whale entanglements will continue. More than 1/3 of recorded Humpback whale incidents along the Queensland coastline are in fact due to the Queensland Shark Control Program and we urgently need to change the current practice in light of an increasing whale population. "Alternative methods are available that do not put the life of humans or whales in danger.” Sea Shepherd Australia's Managing Director Mr Hansen also stated: “Sea Shepherd is concerned for human safety. It is not a question of protecting human safety at cost to the marine environment. You can have both human safety and marine animal protection with the many non-lethal alternatives to nets and drum lines available right now.”
Originally published at: http://www.seashepherd.org.au/news-and-commentary/news/sea-shepherd-calls-for-shark-net-removal-in-queensland.html
4 May 2018
Given white sharks get the (sea)lion’s share of media attention, you may be surprised to learn that we don’t know a whole lot about them. Sure, we know some pretty cool stuff already: they give birth to live young, can swim over 60km an hour and are an apex predator. But because they swim huge distances and are lone travellers it’s hard to get to know them really well. Scientists love a challenge though, so, courtesy of their tireless efforts to study these great creatures, here are four facts you probably didn’t know.
Tagging data and genetic evidence suggests two populations of white sharks Carchardon carcharias (commonly known as the great white shark) exist in Australia: an eastern population ranging from Tasmania to central Queensland and across to New Zealand, and a southern-western population ranging from western Victoria to north-western Western Australia.
There’s a popular saying in the marine world: ‘counting fish is like counting trees, but you can’t see them and they move around all the time.’ Sounds impossible, right? Not for our scientists: in a world first we’ve used a unique combination of electronic tagging and tracking, collection of tissue samples, and a combined genetic and statistical technique called ‘close-kin mark recapture’ to estimate the Australian white shark populations. ‘Close-kin mark recapture’ means we compared the genetic data from juvenile white sharks to figure out how many shared a mother or father. This number can reveal the overall number of breeding adults: a smaller adult population means lots of half and full brothers and sisters, and vice versa. Through the juvenile’s DNA, we’re learning a whole lot about the adult population without having to track them down.
The only catch – you need to know where the cool kids hang (the nursery areas for juvenile white sharks) so you can tag them and collect samples. The eastern juveniles have a few choice locations but their southern-western counterparts are keeping tight-lipped about their favourite spots, meaning we couldn’t conduct the same study with them. Despite this, we were able to estimate the southern-western adult population size to be 1460 (with a range of between 760 and 2250).
But what of the eastern population? We estimate the total population to be 5,460 (with a range of between 2909 and 12,802). We’re not sure if this is historically high, low or somewhere in-between because we have nothing to compare it with, but at least we now have a starting point.
White sharks take a relatively long time to reach maturity — 12 to 15 years — which means they’re slow to reproduce. These are the badges of evolutionary honour a species gets to wear for being extremely successful. However, these same traits mean that if the number of mature white sharks dropped suddenly, the entire species could be under threat. Until now, we had no idea how many juvenile sharks survive to maturity, an important piece of the population puzzle. Another incredible thing our researchers have uncovered is the mortality rate of juvenile sharks in the eastern population. Using data from around 70 juvenile sharks fitted with an acoustic emitter we estimated that juvenile sharks had an annual survival rate of around 73 per cent.
While it’s true the overall number of shark attacks has gradually increased in the past few decades in Australia, many different factors unrelated to shark numbers contribute to the overall increase in shark attacks. These include human population trends, changes in human population distribution and regional demographics, as well as variations in lifestyle and behaviour of people over time. However, clusters of shark attacks cannot be attributed to increases in human use of the ocean, or sudden increases in overall shark population size, because neither of these change over such short periods.
There are, for example, high human-use areas where white sharks are abundant but the incidence of shark attack is low. The drumline program in Western Australia revealed a significant number of tiger sharks present in coastal waters off Perth, yet no attacks have been attributed to this species in the area since 1925 according to the Australian Shark Attack file. Incidence and frequency of shark attacks may not relate directly to local shark abundance and cannot be used as a proxy for shark population trend.
So, what does all this new information mean? Now that we have a starting point for shark populations, we’ll be repeating the process over time to build population trends – a crucial step for developing effective policy outcomes for conservation and risk management.
Original article published https://blog.csiro.au/4-things-didnt-know-white-sharks/
9 February 2018
Scientists from James Cook University (JCU) and the Australian Institute of Marine Science (AIMS) have developed a new method to study microplastics swallowed by sea turtles.
The new technique will help assess whether microplastics are as dangerous to turtles as larger pieces of plastic.
Recent estimates suggest there are more than 5 trillion pieces of plastic debris floating in the world's oceans, a figure which doesn’t include waste on beaches or the seafloor.
JCU’s Associate Professor Ellen Ariel said contamination of marine life by microplastics – pieces of plastic smaller than 5 mm in length - is poorly known and likely to be under-reported.
AIMS@JCU student Alexandra Caron, led the study. “As with bigger pieces of plastic, once swallowed, ingested microplastics may impact organisms physically as well as physiologically as they can leach associated plastic chemicals or other absorbed pollutants into the animal causing toxicity,” she said.
Sea turtles are at particular risk from plastics in the oceans because the seven species of marine turtles are already categorised as vulnerable to critically endangered.“They look for things like jellyfish to eat, and a piece of soft floating plastic can appear very similar. Plastic debris can also become entangled among green turtle food sources such as seagrass leaves and seaweed. Turtles don’t have the capacity to regurgitate, so plastic particles tend to be swallowed and accumulate in the gut,” said Associate Professor Ariel.
Under the supervision of AIMS marine chemist Dr. Cherie Motti the new method was applied. It involves a sequence of chemical treatments designed to separate out swallowed plastic particles from plant and animal food remains as well as any sediment the turtle has swallowed during feeding. “We examined the gut of two green turtles using this new method, and even with this small sample set, found seven microplastics consisting of two plastic paint chips and five synthetic fabric particles. That’s in addition to also finding 4.5 m of nylon line and some soft plastic pieces entangled in the gut,” said Dr Motti.
“The new technique will increase our knowledge of the role plastic pollution plays in declining turtle health. But it has already highlighted the need for increased efforts in plastic pollution mitigation and reduction into the marine environment,” said JCU Professorial Research Fellow Dr Jon Brodie.
17 April 2018 from www.aims.gov.au
Thanks to movies and nature videos, many people know that bizarre creatures live in the ocean’s deepest, darkest regions. They include viperfish with huge mouths and big teeth, and anglerfish, which have bioluminescent lures that make their own light in a dark world.
However, the world’s deepest-dwelling fish – known as a hadal snailfish – is small, pink and completely scaleless. Its skin is so transparent that you can see right through to its liver. Nonetheless, hadal snailfish are some of the most successful animals found in the ocean’s deepest places.
Our research team, which includes scientists from the United States, United Kingdom and New Zealand, found a new species of hadal snailfish in 2014 in the Mariana Trench. It has been seen living at depths of almost 27,000 feet (8,200 meters). We recently published its scientific description and officially christened it Pseudoliparis swirei. Studying its adaptations for living at such great depths has provided new insights about what kinds of life can survive in the deep ocean.
We discovered this fish during a survey of the Mariana Trench in the western Pacific Ocean. Deep-sea trenches form at subduction zones, where one of the tectonic plates that form the Earth’s crust slides beneath another plate. They extend 20,000 to 36,000 feet deep below the ocean’s surface. The Mariana Trench is deeper than Mount Everest is tall.
Ocean waters in these trenches are known as the hadal zone. Our team set out to explore the Mariana Trench from top to bottom in an effort to understand what lives in the hadal zone; how organisms there interact; how they survive under enormous pressure created by six to seven miles of water above them; and what role hadal trenches play in the global ocean ecosystem.
Sending instruments to the ocean floor is pretty straightforward. Bringing them back up is not. Researchers studying the deep sea often use nets, cameras or robots connected to ships by cables. But a 7-mile-long cable, even if it is very strong, can break under its own weight.
We used free-falling landers – mechanical platforms that carry instruments and steel weights and are not connected to the ship. When we deploy landers, it takes about four hours for them to sink to the bottom. To call them back, we use an acoustic signal that causes them to release their ballast and float to the surface. Then we search for them in the water (each carries an orange flag), retrieve them and collect their data.
Hadal trenches are named after Hades, the Greek god of the underworld. To humans, they are harsh, extreme environments. Pressure is as high as 15,000 pounds per square inch – equivalent to a large elephant standing on your thumb, and 1,100 times greater than atmospheric pressure at sea level. Water temperatures are as low as 33 degrees Fahrenheit (1 degree Celsius). Yet, a host of animals thrive under these conditions.
Our team put down cameras baited with mackerel to attract mobile animals in the trench. At shallower depths, from approximately 16,000 to 21,000 feet (5,000-6,500 meters) on the abyssal plain, we saw large fish such as rattails, cusk eels and eel pouts. At the upper edges of the trench, below 21,000 feet, we found decapod shrimp, supergiant amphipods (swimming crustaceans), and small pink snailfish. This newly discovered species of snailfish that lives to near 27,000 feet (8,200 meters), is now the world’s deepest living fish.
At the trench’s greatest depths, near 36,000 feet (11,000 meters), we saw only large swarms of small scavenging amphipods, which are somewhat similar to garden pill bugs. Amphipods live all over the ocean but are highly abundant in trenches. The Mariana snailfish that we filmed were eating these amphipods, which make up most of their diet.
The Mariana Trench houses the ocean’s deepest point, at Challenger Deep, named for the HMS Challenger expedition, which discovered the trench in 1875. Their deepest sounding, at nearly 27,000 feet (8,184 meters), was the greatest known ocean depth at that time. The site was named Swire Deep, after Herbert Swire, an officer on the voyage. We named the Mariana snailfish Pseudoliparis swirei in his honor, to acknowledge and thank crew members who have supported oceanographic research throughout history.
Hadal snailfish have several adaptations to help them live under high pressure. Their bodies do not contain any air spaces, such as the swim bladders that bony fish use to ascend and descend in the water. Instead, hadal snailfish have a layer of gelatinous goo under their skins that aids buoyancy and also makes them more streamlined.
Hadal animals have also adapted to pressure on a molecular level. We’ve even found that some enzymes in the muscles of hadal fish are adapted to function better under high pressure.
Whitman College biologist Paul Yancey, a member of our team, has found that deep-sea fish use a molecule called trimethyl-amine oxide (TMAO) to help stabilize their proteins under pressure.
However, to survive at the highest water pressures in the ocean, fish would need so much TMAO in their systems that their cells would reach higher concentrations than seawater. At that high concentration, water would tend to flow into the cells due to a process called osmosis, in which water flows from areas of high concentration to low concentration to equalize. To keep these highly concentrated cells from rupturing, fish would have to continually pump water out of their cells to survive.
The evidence suggests that fish don’t actually live all the way to the deepest ocean depths because they are not able to keep enough TMAO in their cells to combat the high pressure at that depth. This means that around 27,000 feet (8,200 meters) may be a physiological depth limit for fish.
There may be fish that live at levels as deep, or even slightly deeper, than the Mariana snailfish. Different species of hadal snailfish are found in trenches worldwide, including the Kermadec Trench off New Zealand, the Japan and Kurile-Kamchatka trenches in the northwestern Pacific, and the Peru-Chile Trench. As a group, hadal snailfish seem to have found an unlikely haven in a place named for the proverbial hell.
The first thing to say about shark attack deaths is that they are very rare, with only about two per year in Australia. But still, every year without fail, people die from shark bites, both here and around the world.
According to official statistics, the United States records by far the most unprovoked shark bites – an average of 45 per year over the past decade. However, only 1.3% of these incidents were fatal – 0.6 deaths per year.
Australia records fewer bites than the US (an average of 14 per year), but a much greater proportion of them are deadly: (1.5 per year, or close to 11%). So what is it that (relatively speaking) makes Australia more prone to deadly shark attacks?
My new book Shark Attacks: Myths, Misunderstandings and Human Fear addresses this and other questions about sharks, with the aim of dispelling common myths and providing the knowledge needed for decisions made on science rather than fear and emotion.
In a way, Australia has a “perfect storm” of conditions for serious shark attacks. The first reason is that Australians (and visitors to Australia) love the ocean. Some 85% of Australians live within 50km of the coast, and Australian coastal areas account for the most prominent growth outside of capital cities. Beaches are also favoured recreational destinations in Australia and coastal locations are heavily targeted in tourism, attracting nearly 60% of international tourists.
Next, the sharks themselves. Australia has the world’s highest diversity of sharks and rays, including roughly 180 of the 509 known shark species.
But neither of these factors, even taken together, is enough to explain why deaths are more prevalent in Australia. What we really need to look at is dangerous sharks.
Only 26 shark species have been definitively identified as biting humans without provocation, although the true number is likely to be somewhat higher. Of these 26 species, 22 (85%) are found in Australian waters.
All 11 of the species known to have caused fatal unprovoked bites on humans can be found in Australian waters. And crucially, Australia’s coastal waters are home to all of the “big three” deadly species: white sharks, tiger sharks, and bull sharks.
These species account for all but three of the fatal shark attacks worldwide from 1982-2011. All of the big three species are inquisitive, regularly frequent coastal environments, and are formidably big and strong.
They also have complex, unpredictable behaviour. But despite this difficulty, we can identify factors that make them more likely to swim in areas routinely used by humans.
Most fish are ectothermic, or cold-blooded, with body temperatures very close to that of the surrounding water. This restricts their range to places where the water temperature is optimal.
In contrast, white sharks and a few other related species can retain the heat generated by their muscles predominantly during swimming, enabling them to be swift and agile predators even in cold water. They do this with the help of bunches of parallel arteries and veins in their brains, eyes, muscles and stomachs that function as “heat exchangers” between incoming and outgoing blood, allowing them to keep these crucial organs warm.
White sharks are so good at retaining heat that their core body temperature can be up to 14.3℃ above the surrounding water temperature. This allows them to move seasonally up and down Australia’s east and west coasts, presumably following migrating prey species.
Bull sharks, meanwhile, are the only sharks known to withstand wide variations in water salinity. This means they can easily move from salty oceans to brackish estuaries and even travel thousands of kilometres up river systems. As a result they can overlap with human use areas such as canals, estuaries, rivers and even some lakes. One female bull shark was observed making a 4,000km round-trip to give birth in a secluded Madagascan estuary rather than the open ocean.
As a result, most bull sharks found in river systems are juveniles, but these areas may also be home to large, pregnant females who need to eat more prey to sustain themselves. As rivers are often clouded by sediment, there is an increased risk that a human may be mistaken for prey in this low-visibility environment.
Tiger sharks mainly stay in coastal waters, although they also venture into the open ocean. Their movements are unpredictable, they eat a wide range of prey, are naturally curious and opportunistic, and can be aggressive to humans.
Tiger sharks are clever too – they are thought to use “cognitive maps” to navigate between distant foraging areas, and have hunting ranges that span hundreds of thousands of square kilometres so as to maintain the element of surprise. As a result, tiger sharks’ distribution in Australian waters covers all but the country’s southern coast.
Taken together, it’s clear that Australia’s waters are home to three predators that can pose a real danger, even if only an accidental one, to humans.
But remember that shark attacks are incredibly rare events, and fatal ones even rarer still. There are also lots of tips we can use to minimise the risk of having a negative encounter with a shark.
Don’t swim in murky, turbid or dimly lit water, as sharks may not be able to see you properly (and you may not be able to see them). Avoid swimming in canals, or far from the shore, or along dropoffs. Swim in designated areas and with others, and avoid swimming where baitfish (or bait) may be present. And of course, always trust your instincts.
Tiger sharks are one of the most successful large predators in the world’s oceans, but studying what they eat has been a challenge for researchers. Historically diet is studied through examining stomach contents, but scientists at the Australian Institute of Marine Science (AIMS) and collaborators are leading the way in understanding more about the feeding habits of sharks from their skin tissue. This allows us to learn about shark diet based on a quick non-lethal approach.
In a recent study, AIMS marine biologists Dr Luciana Ferreira, Dr Michelle Thums, Dr Mark Meekan and co-authors from a number of Australian universities, revealed their findings after examining the tissue samples of 273 tiger sharks from Western Australia to New South Wales and the Great Barrier Reef. Samples of blood and muscle tissue of tiger sharks showed information on the prey, position of individual sharks in the food chain, and even what type of habitat (coastal or offshore, seabed or open water) the animal had been feeding in.
Dr Ferreira said tiger sharks are large mobile animals and to ensure sustainable and resilient populations, we need better data on their feeding and behaviors. “In terms of predators, if we can understand the shark’s motivations and how they are using habitats, we can also understand their function within these habitats,” she said.
Difficulties involved in the direct observation of feeding behaviour of marine megafauna such as tiger sharks, has led to the use of alternative techniques to provide insights into the process of their foraging. One of the most common of these is the analysis of stable isotopes of carbon and nitrogen in their tissues, which can provide information on diet, feeding position in the food chain and interactions among different species, and their migratory movements. “Our analysis of stable isotopes shows that the functional role of tiger sharks in food-webs varied among different marine habitats we sampled along the tropical and temperate coasts of Australia,” Dr Ferreira said.
“Tiger sharks in Shark Bay and Ningaloo Reef in Western Australia, and on the Great Barrier Reef had long-term diets based in seagrass and reef-associated food webs. In these habitats they are focussed on turtles and dugong as prey. “In contrast, when sharks were sampled in more temperate habitats such the waters off New South Wales and southern Queensland, the composition of their tissues reflected a diet based on more pelagic [ocean-going] food webs, and they were focused on large fish. “Tiger sharks occupied roles at the top of food webs at Shark Bay in Western Australia and on the Great Barrier Reef, but not at Ningaloo Reef or off the coast of NSW. “This means the local environment and prey community appear to be the most important determinants of the diet of tiger sharks.” Dr Ferreira said the research confirmed the role of tiger sharks in Australian coastal ecosystems as opportunistic, flexible predators.
The research paper ‘The trophic role of a large marine predator, the tiger shark Galeocerdo cuvier’ is published in Nature Scientific Reports.
9 November 2017, Australian Institute of Marine Science, 2017
Indo-Pacific bottlenose dolphins (Tursiops aduncus) are a regular sight in the waters around Australia, including the Bunbury area in Western Australia where they attract tourists.
The dolphin population here, about 180km south of Perth, has been studied quite intensively since 2007 by the Murdoch University Cetacean Unit. We know the dolphins here have seasonal patterns of abundance, with highs in summer/autumn (the breeding season) and lows in winter/spring.
But in winter 2009, the dolphin population fell by more than half.
This decrease in numbers in WA could be linked to an El Niño event that originated far away in the Pacific Ocean, we suggest in a paper published today in Global Change Biology. The findings could have implications for future sudden drops in dolphin numbers here and elsewhere.
The El Niño Southern Oscillation (ENSO) results from an interaction between the atmosphere and the tropical Pacific Ocean. ENSO periodically fluctuates between three phases: La Niña, Neutral and El Niño.
During our study from 2007 to 2013, there were three La Niña events. There was one El Niño event in 2009, with the initial phase in winter being the strongest across Australia.
Coupled with El Niño, there was a weakening of the Leeuwin Current, the dominant ocean current off WA. There was also a decrease in sea surface temperature and above average rainfall.
ENSO is known to affect the strength of the south-ward flowing Leeuwin Current.
During La Niña, easterly trade winds pile warm water on the western side of the Pacific Ocean. This westerly flow of warm water across the top of Australia through the Indonesian Throughflow results in a stronger Leeuwin Current.
During El Niño, trade winds weaken or reverse and the pool of warm water in the Pacific Ocean gathers on the eastern side of the Pacific Ocean. This results in a weaker Indonesian Throughflow across the top of Australia and a weakening in strength of the Leeuwin Current.
The strength and variability of the Leeuwin Current coupled with ENSO affects species biology and ecology in WA waters. This includes the distribution of fish species, the transport of rock lobster larvae, the seasonal migration of whale sharks and even seabird breeding success.
The question we asked then was whether ENSO could affect dolphin abundance?
These El Niño associated conditions may have affected the distribution of dolphin prey, resulting in the movement of dolphins out of the study area in search of adequate prey elsewhere.
This is similar to what happens for seabirds in WA. During an El Niño event with a weakened Leeuwin Current, the distribution of prey changes around seabird’s breeding colonies resulting in a lower abundance of important prey species, such as salmon.
In southwestern Australia, the amount of rainfall is strongly connected to sea surface temperature. When the water temperature in the Indian Ocean decreases, the region receives higher rainfall during winter.
High levels of rainfall contribute to terrestrial runoff and alters freshwater inputs into rivers and estuaries. The changes in salinity influences the distribution and abundance of dolphin prey.
This is particularly the case for the river, estuary, inlet and bay around Bunbury. Rapid changes in salinity during the onset of El Niño may have affected the abundance and distribution of fish species.
In 2009, there was also a peak in strandings of dead bottlenose dolphins in WA (between 1981-2010), but the cause of this remains unknown.
Of these strandings, in southwest Australia, there was a peak in June that coincided with the onset of the 2009 El Niño.
Specifically, in the Swan River, Perth, there were several dolphin deaths, with some resident dolphins that developed fatal skin lesions that were enhanced by the low-salinity waters.
Our study is the first to describe the effects of climate variability on a coastal, resident dolphin population.
We suggest that the decline in dolphin abundance during the El Niño event was temporary. The dolphins may have moved out of the study area due to changes in prey availability and/or potentially unfavourable water quality conditions in certain areas (such as the river and estuary).
Read more: Explainer: El Niño and La Niña
Long-term, time-series datasets are required to detect these biological responses to anomalous climate conditions. But few long-term datasets with data collected year-round for cetaceans (whales, dolphins and porpoises) are available because of logistical difficulties and financial costs.
Continued long-term monitoring of dolphin populations is important as climate models provide evidence for the doubling in frequency of extreme El Niño events (from one event every 20 years to one event every ten years) due to global warming.
With a projected global increase in frequency and intensity of extreme weather events (such as floods, cyclones), coastal dolphins may not only have to contend with increasing coastal human-related activities (vessel disturbance, entanglement in fishing gear, and coastal development), but also have to adapt to large-scale climatic changes.
Kate Sprogis, Research associate, Murdoch University; Fredrik Christiansen, Postdoctoral Research Fellow, Murdoch University; Lars Bejder, Professor, Cetacean Research Unit, Murdoch University, Murdoch University, and Moritz Wandres, Oceanographer PhD Student, University of Western Australia
9 October 2017
Shark diving tourism is a growing industry estimated to be worth more than $25.5 million annually to Australia’s regional economy.
A new report has documented the value on marine wildlife tourism, underlining a need for adequate management of shark species to ensure a sustainable dive tourism industry.
A collaboration between the Australian Institute of Marine Science (AIMS), Flinders University, University of Western Australia, and Southern Cross University documented the industry of four major shark viewing industries across the Australian coast.
AIMS marine biologist and co-author of the study Dr Mark Meekan said the research aimed to provide an estimate of the economic value of shark diving tourism across Australia to help inform decisions about how sharks are managed.
Dr Meekan said whale sharks, known as the gentle giants of the sea, were the most popular drawcard for tourists who spent an estimated $11.6 million for the snorkelling experience. “Ecotourism focused on these animals is now a growing and profitable industry, with a focus that not only uses sharks as a renewable resource, but also engages people in their conservation,” he said.
“In Australia, there are four major shark tourism industries, which include snorkelling with whale sharks off Ningaloo Reef in Western Australia, cage diving with white sharks off Port Lincoln in South Australia, diving with grey nurse sharks off the coast of New South Wales and Queensland, and swimming with reef sharks at Osprey Reef in far North Queensland.”
The study surveyed 711 tourist divers over a one year period and documented their expenditure, including accommodation, transport, living costs, and other related activities during divers’ trips. Flinders University Associate Professor Charlie Huveneers, lead author of the study and research leader of the Southern Shark Ecology Group, said the white shark cage-diving industry off Port Lincoln, South Australia, was the second most valuable shark viewing industry contributing $7.8 million in direct costs to the economy in 2013–2014. “On top of costs directly associated with shark viewing, white shark and whale shark tourists spend as much again in additional expenditure in the region,” Assoc Prof Huveneers said.
”We found 83 per cent of the white shark cage-divers would not have visited the Port Lincoln region and spent money there if a cage-diving opportunity had not been available.
“These additional revenues show that the economic value of this type of tourism do not flow solely to the industry, but are also spread across the region where it is hosted, even in countries with developed economies that are not typically considered to have a dependence on tourism for revenue.”
Assoc Prof Huveneers said wildlife tourism was one of the fastest growing sectors of the tourism industry, but the impact to the natural environment must be measured. “This reiterates the importance of adequate management of these industries to ensure sustainable practices, so future generations have the opportunity to view and interact with sharks in the wild in the same way that we currently can,” he said.
Dr Meekan said about half the white shark divers were domestic visitors but the highest percentage of domestic tourists were found in the grey nurse shark-diving industry, at 59 per cent. Most tourists in whale shark snorkelling tours were international tourists (55%) and only 29% were Australian.
Total number of divers at each of the locations during the study from March 2013 to June 2014:
Osprey Reef, far North Queensland, 1, 848 tourist divers (reef sharks)
Neptune Islands, South Australia, 10,236 tourist divers (white sharks)
Ningaloo Reef, Western Australia, 22,124 tourist divers (whale sharks)
The combined total of divers to four locations in South East Queensland (Wolf Rock and Julian Rock), and NSW (Fish Rock and Magic Point) 13,978 tourist divers (grey nurse sharks)
The paper 'The economic value of shark-diving tourism in Australia' has been published in the journal Reviews in Fish Biology and Fisheries.
Original article from Australian Institute of Marine Science (2017)
AIMS 12 September 2017
The federal government’s new draft marine park plans are based on an unsubstantiated premise: that protection of Australia’s ocean wildlife is consistent with activities such as fishing and oil and gas exploration.
Under the proposed plans, there would be no change to the boundaries of existing marine parks, which cover 36% of Commonwealth waters, or almost 2.4 million square kilometres. But many areas inside these boundaries will be rezoned to allow for a range of activities besides conservation.
The plans propose dividing marine parks into three types of zones:
Crucially, under the new draft plans, the amount of green zones will be almost halved, from 36% to 20% of the marine park network, whereas yellow zones will almost double from 24% to 43%, compared with when the marine parks were established in 2012.
The government has said that this approach will “allow sustainable activities like commercial fishing while protecting key conservation features”.
But like the courtiers told to admire the Emperor’s non-existent new clothes, we’re being asked to believe something to be true despite strong evidence to the contrary.
The new plans follow on from last year’s release of an independent review, commissioned by the Abbott government after suspending the previous network of marine reserves implemented under Julia Gillard in 2012.
Yet the latest draft plans, which propose to gut the network of green zones, ignore many of the recommendations made in the review, which was itself an erosion of the suspended 2012 plans.
The extent of green zones is crucial, because the science says they are the engine room of conservation. Fully protected marine national parks – with no fishing, no mining, and no oil and gas drilling – deliver far more benefits to biodiversity than other zone types.
The best estimates suggest that 30-40% of the seascape should ideally be fully protected, rather than the 20% proposed under the new plans.
Partially protected areas, such as the yellow zones that allow fishing while protecting the seabed, do not generate conservation benefits equivalent to those of full protection.
Environment minister Josh Frydenberg has pointed out that, under the new plans, the total area zoned as either green or yellow will rise from 60% to 63% compared with the 2012 network. But yellow is not the new green. What’s more, yellow zones have similar management costs to green zones, which means that the government is proposing to spend the same amount of money for far inferior protection. And as any decent sex-ed teacher will tell you, partial protection is a risky business.
Let’s take a couple of examples, starting with the Coral Sea Marine Park. This is perhaps the most disappointing rollback in the new draft plan. The green zone, which would have been one of the largest fully protected areas on the planet, has been reduced by half to allow for fishing activity in a significantly expanded yellow zone.
This yellow zone would allow the use of pelagic longlines to fish for tuna. This is despite government statistics showing that around 30% of the catch in the Eastern Tuna and Billfish fishery consists of species that are either overexploited or uncertain in their sustainability, and the government’s own risk assessment that found these types of fishing lines are incompatible with conservation.
What this means, in effect, is that the plans to establish a world-class marine park in the Coral Sea will be significantly undermined for the sake of saving commercial tuna fishers A$4.1 million per year, or 0.3% of the total revenue from Australia’s wild-catch fisheries.
Contrast this with the A$6.4 billion generated by the Great Barrier Reef Marine Park in 2015-16, the majority of which comes from non-extractive industries.
This same erosion of protection is also proposed in Western Australia, where the government’s draft plan would reduce green zones by 43% across the largest marine parks in the region.
Again, this is despite clear evidence that the fishing activities occurring in these areas are not compatible with conservation. Such proposals also ignore future pressures such as deep-sea mining.
The overall effect is summarised neatly by Frydenberg’s statement that the government’s plans will:
…increase the total area of the reserves open to fishing from 64% to 80% … (and) make 97% of waters within 100 kilometres of the coast open for recreational fishing.
Science shows that full protection creates resilience by supporting intact ecosystems. Fully protected green zones recover faster from flooding and coral bleaching, have reduced rates of disease, and fend off climate invaders more effectively than areas that are open to fishing.
Green zones also contribute indirectly to the blue economy. They help support fisheries and function as “nurseries” for fish larvae. For commercial fisheries, these sanctuaries are more important than ever in view of the declines in global catches since we hit “peak fish” in 1996.
Of course it is important to balance conservation with sustainable economic use of our oceans. Yet the government’s new draft plan leaves a huge majority of Australia’s waters open to business as usual. It’s a brave Emperor who thinks this will protect our oceans.
So let’s put some real clothes on the Emperor and create a network of marine protection that supports our blue economy and is backed by science.
24 July 2017
The AIMS Long-term Monitoring Program has released an update on the condition of the Great Barrier Reef (GBR) based on survey data gathered across the entire GBR over the last 32 years. The update, which assesses data captured up to February 2017, describes a system under considerable pressure.
Following on from an AIMS publication in 2012, which described a 27-year decline in coral cover on the Reef, and last year’s update, today’s update shows that average hard coral cover (the most common indicator of reef health) across the entire system declined further during 2016, but the magnitude and trajectory of change varied between the Northern, Central and Southern regions.
“The Great Barrier Reef is a large, dynamic and important ecosystem, so it is essential that we continually monitor its condition and trends, and update our understanding of the reef’s current health in a broader context”, says Dr Britta Schaffelke, Program Leader for the AIMS ‘Healthy and Resilient GBR’ Program.
“These data show that the impacts of disturbances such as coral bleaching, crown-of-thorns starfish and cyclones vary along the length of the Reef. The decline in coral cover due to severe disturbances over the past two years is quite concerning.”
Dr Hugh Sweatman, AIMS Research Scientist and head of the monitoring team explains, “Our most recent data show that in the Northern region, coral cover is less than half of what is was in 2011, which is unprecedented for the region in the last 30+ years.
“This decline is largely due to severe coral bleaching event that caused significant mortality in 2016, in combination with 2 severe cyclones and continued crown-of-thorns outbreaks.
“The Central region was experiencing a general increase in coral cover until bleaching reduced this in 2016. Coral cover in the Southern region continues to increase from low levels in 2009.”
The Southern GBR region during 2016/2017. Coral cover on reefs of the Southern GBR has recovered remarkably since it was obliterated by storms in 2008 and then Cyclone Hamish in 2009. The reef slopes of Lady Musgrave Reef and Erskine Reef, pictured here, are now covered in tabulate and branching Acropora sp. corals.
The update includes information taken from the extensive surveys taken over 2016 and into early 2017, but does not include data after the 2017 severe bleaching event, or Tropical Cyclone Debbie. This information will be included in future updates.
Long-term outlook for the Great Barrier Reef
The researchers highlight that it is difficult to predict the recovery of the Great Barrier Reef. “Despite the fact that we have over 30 years of information from the Program, we are only now starting to have data gathered over a sufficiently long period of time to allow us to understand the reef recovery process under a changing climate,” says Dr Schaffelke.
“Recent analysis of this long-term data set shows that recovery can be severely hampered by impacts associated with climate change, particularly increasing sea temperatures.”
A recent AIMS study indicated that recovery after a major heat-stress event in 2002 on the GBR was slowed, compared to previous recovery periods, and that affected reefs suffered high rates of coral disease. A separate AIMS study on the effects of cyclones concluded that, while recovery can be strong on some reefs, the projected increases in intensity of cyclones as a result of climate change could make it more difficult for reefs to recuperate.
Read the update in full here.
AIMS’ Long-term Monitoring Program is the longest, most comprehensive source of information on the health of corals for the Great Barrier Reef.
June 1 2017
Original article from Australian Institute of Marine Science (2017)
It is easy to feel overwhelmed when confronted with reports of the second mass bleaching event on the Great Barrier Reef in as many years. But there is a way to help scientists monitor the reef’s condition.
CoralWatch is a citizen science program started at The University of Queensland 15 years ago, with two main aims: to monitor the environment on a vast scale, and to help people get informed about marine science.
These goals come together with coral health monitoring. Divers, snorkelers or people walking around reef areas during low tides can send us crucial information about coral bleaching, helping us to build detailed pictures of the health of different reefs.
Participants can use a colour chart, backed up through the CoralWatch app or website, to measure accurately the colour and type of coral they see. The chart covers 75% of known corals, and can be used with no prior training.
We also ask people to enter the type of coral (branching, boulder, plate or soft), the location, and the weather. This allows scientists to identify the location and extent of any problems quickly (and is an excellent way to learn more about our reefs).
In fact, you don’t even have to go to a reef to participate and discover through CoralWatch; we have classroom and virtual reef systems, and just talking the problem through can help.
The graphs shown below are samples of CoralWatch data from the northern and southern reef during 2016’s catastrophic mass bleaching event, while the pair of graphs further down the page show data from just a few days ago at Lady Elliot Island and the very remote North Mariana Islands in the West pacific.
The Heron Island graph shows a healthy reef, as the southern areas of the reef escaped the worst of the bleaching last year. In contrast, Monsoon Reef (which lies off Port Douglas) and many others in the north bleached badly, or in some cases simply died.
Scores averaging between four and six are normal and represent good levels of symbiotic algae, which generate nutrients for the coral. Scores below three signify that coral is in distress.
The impact of this year’s mass bleaching is still being quantified. However, reefs in the middle section and far south of the reef – such as Lady Elliot Island – are now showing varying degrees of bleaching, from light to severe. Many of the remaining corals in the north are also showing signs of bleaching again.
What seems certain is that we will lose many more corals, along with the fish and invertebrate life they support, again this year.
The results for the North Mariana Islands, from a CoralWatch survey conducted last week, shows mid-level coral bleaching and demonstrates that even very remote reefs are not climate-proof.
CoralWatch doesn’t only help build a detailed picture of reef health. Like other citizen science projects, such as Reef Check, it can help speed up our fatally slow response to climate change. There are three key benefits.
First, we need to improve mutual understanding between scientists and the public. The CoralWatch mantra is: tell me and I’ll forget; teach me and I may remember; involve me and I’ll learn. Citizen science is a natural fit for everyone, no matter your level of education or knowledge.
Children are the citizens of the future, and helping them to understand their changing world is a moral and social imperative. CoralWatch works closely with schools and groups like the Marine Teachers Association of Queensland, and is used in more than 75 countries worldwide.
Second, we need to encourage lifestyle change. Many people, as they become more engaged in citizen science, will naturally adopt more environmentally friendly habits. Getting involved in protecting the Great Barrier Reef – and other citizen science projects – can be a great dose of perspective on our place in the natural world.
However, as personally rewarding as they can be, individual lifestyle choices alone won’t deliver the rapid and widespread change we need to save our reefs. That’s why we need to bridge the disconnect between what most of Australia wants and the politicians who ultimately have the power to fast-track change. Citizen scientists are also informed voters and consumers, who can demand better policies from companies and governments.
The future of the Great Barrier Reef is in the hands of Australians, and it will take all of us to preserve it for our children.
Justin Marshall, ARC Laureate Fellow, The University of Queensland; Chris Roelfsema, Research Fellow (Coastal and Marine), The University of Queensland, and Diana Kleine, Coral Watch Project Manager, The University of Queensland
April 12 2017
Scientists have found exceptionally diverse and abundant coral-reef fish communities at submerged oceanic shoals near Ashmore Reef some 400 kilometres off north-western Australia.
The north-west oceanic shoals - natural banks that rise from the seabed, in this case from depths of 200 m up to within 15─50 m of the surface - were found to support the highest fish diversity reported globally for deeper ‘mesophotic’ or middle light level coral reefs (20─80 metre depth) and may support the resilience of shallower coral reef communities.
The study of nine oceanic shoals in the Timor Sea was led by the Australian Institute of Marine Science (AIMS) and reported recently in Coral Reefs.
“Traditionally scientists and managers have focused on understanding threats to shallow coral reef communities,” says Dr Cordelia Moore, a joint research associate from Curtin University and AIMS. “Deeper reefs beyond the reach of SCUBA-based surveys are poorly studied. Our survey used remote monitoring technologies including multibeam acoustics, photography, towed video, remotely operated vehicles and baited remote underwater systems. We found 341 species of fish from 47 families, including 10 shark, five ray and two sea snake species. The fish communities were 1.4 times as diverse and almost twice as abundant as those on similar deeper coral reefs on the Great Barrier Reef.”
The relatively clear waters in the study region allow fauna such as hard corals and macroalgae to grow in depths of up to 60─70 m, supporting diversity similar to shallow reef systems. The fishes may also benefit from enhanced productivity driven by local upwelling and interacting currents. “Characterising these deeper coral-reef communities is critical because mesophotic reefs may provide a unique contribution to biodiversity as well as potentially enhancing the connectivity and resilience of surrounding shallow reefs,” Dr Moore says.
While progress has been made understanding the connectivity within and between coral reefs, the degree of connectivity between shallow and deep coral reef populations is largely unknown. Deeper reefs may act as important refugia, providing a source of larvae, juveniles or adults, to replenish more exposed shallow-water reefs after impacts such as coral bleaching, storms and cyclones, fishing pressure and warming events. This is especially important to understand in regions such as north-western Australia, which is experiencing increasing pressures from human activities such as fishing and petroleum industries.
“Currently, 30% of north-east Australia’s mesophotic reefs are within no-take management zones of the Great Barrier Reef. In contrast, just 1.3% of Australia's north-west oceanic shoals are in designated no-take areas,” Dr Moore says. “Now that we know these habitats support fish biodiversity of global significance, ensuring we understand and manage these deeper reefs is critical.”
The north-west oceanic shoals are of conservation interest at both a regional and global scale. They support many species of conservation interest including the humphead wrasse, greater hammerhead and various sharks, rays and groupers.
Australia’s north-west is one of the country’s most economically significant marine regions, producing most of Australia’s domestic and exported oil and gas. It also has high-value ecological habitats supporting a range of protected species such as dugong, turtle and whale sharks. The need for baseline ecological data for this region was highlighted by the 2009 uncontrolled release from the Montara wellhead platform, which triggered monitoring of key ecological communities to ensure the protection and sustainable management of natural and economic values into the future.
March 23 2017
Original article from Australian Institute of Marine Science (2017)
In the wake of the Great Barrier Reef’s most intense coral bleaching event, researchers at the Australian Institute of Marine Science (AIMS) report that predicted increases in the intensity of tropical cyclones due to climate change could greatly accelerate coral reef degradation and make it far more difficult for reefs to bounce back from disturbances.
Research published today in Global Change Biology investigated whether predicted increases in cyclone intensity might change the nature of coral reefs. AIMS scientists used the world’s largest coral reef ecosystem, the Great Barrier Reef, as a test case to understand what lies ahead for coral reefs.
A team of researchers led by AIMS scientist, Alistair Cheal, first assessed the ecological impacts to the Reef from cyclones, based on multiple data sets collected from the region. The Institute’s Long-term Monitoring Program contributed crucial broad-scale field data from as far back as 1996, including data captured after recent severe cyclone events (Hamish in 2009, Yasi in 2011 and Ita in 2014). “Here at AIMS, we have been closely monitoring reefs along the Great Barrier Reef for over 20 years through the Long-term Monitoring Program. An analysis of the data collected from outer reefs indicates that a recent spate of unusually intense cyclones caused record destruction of corals and great loss of fishes over >1000 km,” stated Mr Cheal, the study’s lead author.
Using modelling tools, the data was then contextualised in terms of future climate-driven threats based on published predictions for increasing cyclone intensity. The scenarios yielded grim consequences for reefs.
“What we found was that the return time of cyclone sequences likely to cause extreme and widespread losses of corals and fishes could increase from hundreds of years, to once every 25 years within this century. This presents a real threat to the status and recovery of coral reef ecosystems,” Mr Cheal concluded.
The implications extend beyond the projected coral and fish losses through associated decreases in biodiversity, increased vulnerability of coral reefs to long-term degradation and associated flow-on effects to social and economic services.
The paper: “The threat to coral reefs from more intense cyclones under climate change” by Alistair J. Cheal, M. Aaron MacNeil, Michael J. Emslie and Hugh Sweatman is available online today.
February 1 2017
Original article from Australian Institute of Marine Science (2017)
If the thought of going into the ocean this summer fills you with trepidation, here are five things you can do to reduce your risk of encountering a shark.
A WA Department of Fisheries report found that of the 26 shark attacks in the State between 1991 and September 2011, only one was within 30m of the shore.
Two-thirds of the attacks were more than 200m offshore, and SCUBA divers and snorkelers made up almost half of shark attack victims. Only three of the attacks were on swimmers.
White sharks prefer cooler waters and two-thirds of the attacks in WA in the 20 years to 2011 occurred in water temperatures below 200C. Only one was in waters above 220C.
This preference for cooler water plays out in statistics showing there is a higher rate of attacks off the southern half of the WA coast.
More attacks also happen in winter and spring rather than summer and autumn, despite more people being in the water in warmer weather.
And by shallows, we mean where the water is less than 5m deep. More than this and your risk of running into a shark increases.
For a long time, the jury was out on these electronic shark repellents but UWA-led research has delivered a result that will be music to ocean lovers’ ears—Shark Shields do help to repel white sharks.
The study found the Shark Shield produced an effective deterrent field of about 1.3m from the devices electrodes.
Shark Shields prevented sharks interacting with a bait 10 out of 10 times on an animal’s first approach, and nine out of 10 times on the second approach.
With models starting at $600 a pop, the device is not for everyone.
But for divers and others with good reason to ignore the first three avoidance strategies, a Shark Shield might be worth considering.
Finally, the Fisheries research was unable to rule out proximity to seal and sea lion colonies as a factor in shark attacks.
While the majority of attacks occurred more than 10km from a colony, the study found this may reflect relatively low levels of human activity in these areas.
It concluded it remains plausible that there is an increased risk of attack near seal and sea lion colonies.
28 January 2017
The first creatures to evolve teeth didn’t have jaws. Many scientists believe these ancient fish developed the first tooth-like structures on their skin that were similar to the “denticle” scales that still cover sharks today, even after 500m years of evolution. It is thought that these denticles gradually migrated into the mouth to form oral teeth. However, research conducted by my colleagues and I suggests modern teeth – at least in sharks – may have also evolved from taste buds. In fact, we have shown that both teeth and taste buds develop from the same stem cells in an embryonic shark’s mouth.
While human taste buds sit separately on the tongue, many animals – particularly non-mammal vertebrates – have taste buds that line the regions of the jaws that also house teeth. We can see this especially clearly in sharks, which have multiple rows of continually regenerating teeth. The regions of a shark’s mouth with the highest concentration of taste buds are directly behind the last row of teeth in both the upper and lower jaws, suggesting an important association between biting and tasting.
By studying shark embryos, we were able to track the stem cells in the mouth before teeth and taste buds formed. We discovered that these cells migrate and contribute to both structures. Even later in development when teeth and taste buds were established, taste-linked cells could still migrate to tooth forming regions deep in the jaw.
These stem cells also govern the teeth’s ability to regenerate throughout the shark’s life, and it turns out the shark’s taste buds also share this ability. This suggests that teeth and taste buds not only develop and function together but may also have a close evolutionary link.
We also tested the idea that teeth in the mouth also share an evolutionary history with skin denticles. Although both are made from similar materials – dentine and enamel-like mineralised tissues – they have a number of clear differences. For example, shark denticles cannot regenerate like their teeth can.
Our research findings echoed this at a genetic level. The way genes are turned on and off in both teeth and denticle cells is almost identical. But a key exception is in a gene known as “sox2”, a stem-cell marker involved in the development and regeneration of many tissues in the body. We found the gene is not turned on in shark denticles but is involved in oral tooth development and regeneration. And it is also expressed in taste buds.
This led us to the new theory that shark teeth actually evolved their regenerative ability from taste buds. We know that taste buds evolved in ancient fishes before oral teeth because taste bud-like structures are present in jawless fishes such as lampreys. So if denticles did migrate into the mouth and evolve into oral teeth, their development may have become linked with that of taste buds, developing from the same cells and adopting their regenerative ability. This might have been because it gave the animals the advantage of tasting and processing food at the same time. Which means sharks may have their taste buds to thank for their conveyor belt of regenerating teeth.
18 January 2017
Researchers from The University of Western Australia and Australian Institute of Marine Science, (AIMS) and collaborators across the Indian Ocean have completed a huge photo-identification study to assess the seasonal habits of whale sharks in the tropics. They were surprised to discover that the male juveniles didn’t seem to venture too far from home. The researchers used photo-identification data, collected by citizen scientists, including crews working on the tour boats, and researchers, to assess the connectedness of five whale shark aggregation (gathering) sites across the entire Indian Ocean over a decade.
Comparing the unique markings of more than 1000 individual whale sharks, the team appraised whether the seasonal gatherings of these animals could be linked by migration. After sifting through over 6000 photos, they found that, on average, 35 per cent of individuals were re-sighted at the same site in more than one year but that no sharks were found to have moved across the Indian Ocean. One shark was tracked between regional localities from the Seychelles to Mozambique, suggesting that links do occur but that populations on either side of the Indian Ocean are likely to be distinct.
PhD researcher and lead author, Samantha Andrzejaczek from UWA’s Oceans Institute and AIMS, said the researchers had initially thought the juveniles crossed oceans to visit other important sites during their migration, however it appeared their movements were strictly regional. “This is good news for our whale sharks, Ms Andrzejaczek said. “Whale sharks are under threat from human impacts of hunting and ship strike and it makes it much easier to plan for conservation if we only have to deal with neighbouring countries in each region rather than localities spread across the entire Indian Ocean.” Not only were the whale sharks staying in the region, many of them returned multiple times to Ningaloo, in Western Australia’s North West. “Our whale sharks at Ningaloo are mostly male teenagers. They don’t become reproductive adults until they grow to sizes of more than eight metres in length and this is thought to take up to 30 years,” Ms Andrzejaczek said. “Our young males don’t seem in any hurry to move on from their feeding grounds at Ningaloo – we have some individuals that have now been sighted here for 19 years and have even matured.”
Study co-author, Dr Mark Meekan of AIMS, said the study also highlighted the unknown facts about these sharks. “Although they are the largest fish in the sea, they are still very hard to find – it’s a very big ocean out there. “We know the teenage males are homebodies, but that does not necessarily apply to the rest of the population,” he said.
Adult females and males are rarely sighted at Ningaloo and at all other locations in the Indian Ocean.
“Finding these animals is going to take some effort, as our computer–simulation analysis of the data showed that we need more photos from more localities just to get a better estimate of migration patterns at even regional scales,” Dr Meekan said. Ms Andrzejaczek said the photo-identification approach was a great opportunity for the public to get involved in whale shark conservation. “Many of the photos used in the study were sourced from tourists who snorkelled with the sharks as part of the tourist industry, as well as the industry videographers and tour guides, she said. “We even downloaded videos from YouTube to get identification shots. “Social media provides a great source of science for charismatic animals like whale sharks and we hope to encourage more engagement across the Indian Ocean.”
November 16 2016
The study, part-funded by Quadrant Energy Ltd and the Department of Parks and Wildlife WA, was published today in Royal Society Open Science.
Original article from Australian Institute of Marine Science (2016)
Japan’s fleet has left port for another season of “scientific” research whaling in the Southern Ocean.
Like last year, there is little that anyone can do to legally rescind Japan’s self-issued lethal research permit – a fact that has led to calls for more pragmatism and less confrontation in efforts to conserve whales.
Such avenues include greater collaboration between the International Whaling Commission (IWC) and other organisations, and a renewed emphasis on marine ecosystem research in the Southern Ocean.
More formally known as the Draft Resolution on Cetaceans and Their Contribution to Ecosystem Functioning, the resolution notes the growing scientific evidence that whale faeces are a crucial source of micronutrients for plankton.
The resolution will lead to a review of the ecological, environmental, social and economic aspects of whale defecation “as a matter of importance”, while the IWC’s Scientific Committee will review the research and identify any relevant knowledge gaps.
Much of the Southern Ocean is described as high-nutrient, low-chlorophyll (HNLC) waters. This means that the despite high concentrations of important nutrients such as nitrate and phosphate, the abundance of phytoplankton is very low.
Phytoplankton is the base of the marine food chain, and plays an important role in the global carbon cycle by removing carbon dioxide in the atmosphere through photosynthesis. However, the growth of phytoplankton in large HNLC regions of the Southern Ocean is limited by the availability of a key micronutrient: iron. In essence, the Southern Ocean is anaemic, and whale poo is the remedy.
It works like this. Antarctic krill graze on phytoplankton, taking up the iron. The krill are then consumed by whales, which store some iron for their own use as an oxygen carrier in their blood (as in ours), but also expel large amounts of iron in their faeces.
Adult blue whales, for example, consume about 2 tonnes of krill a day, and the amount of iron in their faeces is more than 10 million times higher than normal seawater.
Conveniently, whale poo is liquid, and is released at the surface where it can act as a fertiliser to promote phytoplankton growth in the ocean’s sunlit top layers. Therefore, whales are part of a positive feedback loop that helps sustain marine food chains.
More whales obviously make more whale poo, so it makes sense that more research and protection should be afforded to whales to ensure a healthier marine ecosystem.
Scientists collect whale faeces from the surface of the water, making this a great way to do whale research without killing or harming them.
Some have suggested that the legal arguments against scientific whaling are well and truly exhausted, and that controlled commercial whaling could be the next step. Assuming that anti-whaling nations such as Australia would not follow such a pathway, and that hard law options are frustrated, other avenues to end lethal research are needed.
The whale poo resolution also aims to increase the IWC’s existing collaborations with various research organisations. This includes the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), of which Japan is a member. CCAMLR made headlines last month when it approved, by consensus, the world’s largest marine protected area in Antarctica’s Ross Sea.
While the CCAMLR Convention states that nothing in it shall derogate from the rights and obligations under the Whaling Convention, the role of whales are important to CCAMLR’s ecosystem approach to conserving marine life in the Southern Ocean.
Japan’s current whaling program has the stated scientific objective of investigating “the structure and dynamics of the Antarctic marine ecosystem through building ecosystem models”. This aligns with both the research needed for CCAMLR’s ecosystem approach and the Australian Antarctic Division’s own research priorities.
With an emphasis on research such as ecosystem modelling, collaborations that include and value Japan’s abundant non-lethal research in the area could help to most of the stated scientific objectives of Japan’s whaling program without harming whales.
Of course, many people contend that the main purpose of Japan’s whaling program is not scientific. But this doesn’t change the fact that the same old battles at sea and in the courts have done little to prevent the taking of whales. The Whaling Convention cannot be changed, and nor can Japan’s interpretation of it. A different tack is clearly needed in both law and diplomacy.
As the new marine protected area shows, Antarctica is a proven platform of peace. Increasing joint scientific research, and riding on the wave of the recent success in the Ross Sea, may provide fresh dialogue with which to resolve the stalemate. What we need is a newly respectful, non-combative discourse with Japan which, whaling aside, is a brilliant contributor to Antarctic science.
Joint Australian and Japanese research in other areas of Southern Ocean and Antarctic science has a long and friendly history. It is upon these longstanding and positive relationships that research addressing relevant objectives should be focused and funded.
While some, including the Australian Greens, have called for an Australian government vessel to intervene, Japan is whaling in waters that are recognised by most countries as the high seas.
Since the landmark 2014 International Court of Justice ruling, Japan no longer consents to that court’s jurisdiction on matters of living marine resources. And with little recognition of Australian jurisdiction in the area, and the risk of any intervention being illegal under laws of the sea, there is little hope for successful international legal action. Sending an Australian ship to intervene or collect evidence would therefore be largely futile.
On the other hand, researching marine ecosystems in the Southern Ocean is difficult and expensive. Instead of sending a customs vessel, Australia should divert its funds and attention to research that will boost our understanding of the Southern Ocean ecosystem and its role in the global carbon cycle.
By increasing knowledge and recognition of whales’ role in the Southern Ocean ecosystem, the resolution offers yet another avenue for developing norms of non-lethal whale research that are recognised as legitimate by all International Whaling Commission members.
Perhaps in one of Australia’s most vexed diplomatic issues with their close ally, whale poo could pave the way to more intensive and thoughtful scientific collaborations, and help deliver a peaceful end to Japanese whaling in the Southern Ocean.
The author would like to thank Lavy Ratnarajah, a biogeochemist at the Antarctic Climate and Ecosystems CRC, for her kind assistance with the scientific aspects of this article. The views expressed are solely those of the author.
Light pollution is changing the day-night cycle of some fish, dramatically affecting their feeding behaviour, according to our recently published study.
In one of the first studies of its kind, we found that increased light levels in marine habitats, associated with large coastal cities, can significantly change predator-prey dynamics.
We used a combination of underwater video and sonar to spy on these communities and record how their behaviour changed. Like us, the animals in our study slowed down at night. Predatory fish became sluggish and had little appetite.
But when the lights went on some of these same predators disappeared, while others feasted on the well-lit underwater buffet. Overall, there was much greater predation on seafloor-dwelling communities when the night waters were lit.
The dark blanket of night might once have heralded time to rest, but the great pace of human activity has required that nights get shorter and days become artificially longer.
As the sun sets, streetlights flicker to life, generators go into overdrive and the landscape becomes dotted with artificial light, producing some of the most spectacular images from space. The sky glow from major urban centres can be seen more than 300km away.
While this may have enhanced productivity, we are starting to realise that the ecological effects on animals that have evolved under natural day–night cycles are significant.
Artificial lighting of outdoor areas began in earnest in the late 1700s. We have been manipulating lighting regimes for centuries for purposes that include increased egg production in hens and to encourage birds to sing during winter.
However, we have only recently begun to investigate the damaging ecological consequences. We now know that lighting used on offshore energy installations causes increased deaths of migratory birds and beach lighting can cause turtle hatchlings to become disoriented and reduce the chances of a safe journey from nest to sea.
But these are the more obvious impacts of a disrupted day length. More subtle changes in animal behaviours caused by artificial lighting have yet to be illuminated (pun intended!).
Using LED spotlights, we manipulated the light patterns underneath a wharf in Sydney Harbour, illuminating sessile (attached to the seafloor and wharf) invertebrate prey communities to fish predators. We recorded fish numbers and behaviour under different lighting scenarios (day, night and artificially lit night), and the prey communities were either protected or exposed to predators.
Despite different changes in different species, overall we found that more animals were getting eaten. The main predators were yellowfin bream (Acanthopagrus australis) and leatherjackets (Monocanthidae). The prey being consumed included barnacles, bryozoans (encrusting and arborescent), ascidians (solitary and colonial), sponges and bivalves.
Large predators are very important in ecosystems and play a major role in the structure of the whole food chain. If these predators are removed from the system, there are cascading effects and sometimes entire ecosystems collapse.
So we should expect that changes to the behaviour of predators will have major consequences for prey communities. When we turned on the lights, we found prey communities changed to more closely resemble communities exposed to predation during the day. This increase in predation pressure highlights the effect prey communities face under a brightening future, possibly leading to shifts in prey structure with flow-on effects to ecosystem functioning.
About 70% of the world’s largest cities are situated on the coast, and there has been a corresponding increase in urban lighting that also illuminates the underwater world.
We are beginning to understand the effects of artificial light on the natural world around us, but there is still a long way to go – especially in the underwater realm. World populations continue to grow and increasing pressure is placed on our coastal fringes to support this growth, so we need to find solutions to reduce our impact wherever we can.
One solution for light pollution is to control the wavelength of light used depending on the location of the lights. LEDs are increasingly being used because they are effective and cheap to run, but they emit a broad spectrum with peaks in blue and green wavelengths, which penetrate to great depths underwater. Moving towards other spectra, such as red which doesn’t penetrate as far, could reduce the problem.
Ultimately, while our requirement for artificial light at night is unlikely to diminish, darkness remains a necessary component of many animal’s lives. We must do our best to bring back their night.
Damon Bolton, Associate Lecturer in coastal resource management and environmental impact, UNSW Australia; Alistair Becker, Scientific Officer; Emma Johnston, Professor and Pro Vice-Chancellor (Research), UNSW Australia; Graeme Clark, Research Associate in Ecology, UNSW Australia; Katherine Dafforn, Senior Research Associate in Marine Ecology, UNSW Australia, and Mariana Mayer-Pinto, Research Associate in marine ecology, UNSW Australia
November 25 2016
Imagine that you are constantly eating, but slowly starving to death. Hundreds of species of marine mammals, fish, birds, and sea turtles face this risk every day when they mistake plastic debris for food.
Plastic debris can be found in oceans around the world. Scientists have estimated that there are over five trillion pieces of plastic weighing more than a quarter of a million tons floating at sea globally. Most of this plastic debris comes from sources on land and ends up in oceans and bays due largely to poor waste management.
Plastic does not biodegrade, but at sea large pieces of plastic break down into increasingly smaller fragments that are easy for animals to consume. Nothing good comes to animals that mistake plastic for a meal. They may suffer from malnutrition, intestinal blockage, or slow poisoning from chemicals in or attached to the plastic.
Despite the pervasiveness and severity of this problem, scientists still do not fully understand why so many marine animals make this mistake in the first place. It has been commonly assumed, but rarely tested, that seabirds eat plastic debris because it looks like the birds’ natural prey. However, in a study that my coauthors and I just published in Science Advances, we propose a new explanation: For many imperiled species, marine plastic debris also produces an odor that the birds associate with food.
Perhaps the most severely impacted animals are tube-nosed seabirds, a group that includes albatrosses, shearwaters and petrels. These birds are pelagic: they often remain at sea for years at a time, searching for food over hundreds or thousands of square kilometers of open ocean, visiting land only to breed and rear their young. Many are also at risk of extinction. According to the International Union for the Conservation of Nature, nearly half of the approximately 120 species of tube-nosed seabirds are either threatened, endangered or critically endangered.
Although there are many fish in the sea, areas that reliably contain food are very patchy. In other words, tube-nosed seabirds are searching for a “needle in a haystack” when they forage. They may be searching for fish, squid, krill or other items, and it is possible that plastic debris visually resembles these prey. But we believe that tells only part of a more complex story.
Pioneering research by Dr. Thomas Grubb Jr. in the early 1970s showed that tube-nosed seabirds use their powerful sense of smell, or olfaction, to find food effectively, even when heavy fog obscures their vision. Two decades later, Dr. Gabrielle Nevitt and colleagues found that certain species of tube-nosed seabirds are attracted to dimethyl sulfide (DMS), a natural scented sulfur compound. DMS comes from marine algae, which produce a related chemical called DMSP inside their cells. When those cells are damaged – for example, when algae die, or when marine grazers like krill eat it – DMSP breaks down, producing DMS. The smell of DMS alerts seabirds that food is nearby – not the algae, but the krill that are consuming the algae.
Dr. Nevitt and I wondered whether these seabirds were being tricked into consuming marine plastic debris because of the way it smelled. To test this idea, my coauthors and I created a database collecting every study we could find that recorded plastic ingestion by tube-nosed seabirds over the past 50 years. This database contained information from over 20,000 birds of more than 70 species. It showed that species of birds that use DMS as a foraging cue eat plastic nearly six times as frequently as species that are not attracted to the smell of DMS while foraging.
To further test our theory, we needed to analyze how marine plastic debris smells. To do so, I took beads of the three most common types of floating plastic – polypropylene and low- and high-density polyethylene – and sewed them inside custom mesh bags, which we attached to two buoys off of California’s central coast. We hypothesized that algae would coat the plastic at sea, a process known as biofouling, and produce DMS.
After the plastic had been immersed for about a month at sea, I retrieved it and brought it to a lab that is not usually a stop for marine scientists: the Robert Mondavi Institute for Food and Wine Science at UC Davis. There we used a gas chromatograph, specifically built to detect sulfur odors in wine, beer and other food products, to measure the chemical signature of our experimental marine debris. Sulfur compounds have a very distinct odor; to humans they smell like rotten eggs or decaying seaweed on the beach, but to some species of seabirds DMS smells delicious!
Sure enough, every sample of plastic we collected was coated with algae and had substantial amounts of DMS associated with it. We found levels of DMS that were higher than normal background concentrations in the environment, and well above levels that tube-nosed seabirds can detect and use to find food. These results provide the first evidence that, in addition to looking like food, plastic debris may also confuse seabirds that hunt by smell.
Our findings have important implications. First, they suggest that plastic debris may be a more insidious threat to marine life than we previously believed. If plastic looks and smells like food, it is more likely to be mistaken for prey than if it just looks like food.
Second, we found through data analysis that small, secretive burrow-nesting seabirds, such as prions, storm petrels, and shearwaters, are more likely to confuse plastic for food than their more charismatic, surface-nesting relatives such as albatrosses. This difference matters because populations of hard-to-observe burrow-nesting seabirds are more difficult to count than surface-nesting species, so they often are not surveyed as closely. Therefore, we recommend increased monitoring of these less charismatic species that may be at greater risk of plastic ingestion.
Finally, our results provide a deeper understanding for why certain marine organisms are inexorably trapped into mistaking plastic for food. The patterns we found in birds should also be investigated in other groups of species, like fish or sea turtles. Reducing marine plastic pollution is a long-term, large-scale challenge, but figuring out why some species continue to mistake plastic for food is the first step toward finding ways to protect them.
November 14 2016
October 12 2016
In response to the news today that NSW Premier Mike Baird will approve shark mesh nets for Ballina NSW, Sea Shepherd Australia had the following response.
"There is no way that the NSW Government can justify calling this a 'trial'. Shark nets are old technology. We know how they work. We know what they will do. Upwards of 80% of the catch will be by-catch and that will include dolphins from the Richmond River pod. We know that shark bite incidents will still occur as they have at netted beaches in Queensland. These nets will merely give surfers a dangerous false sense of security," remarked Jonathan Clark Queensland Coordinator - Apex Harmony Campaign.
"Back in 1946, after over a decade of shark nets off the NSW coast and many unwanted shark encounters at netted beaches, the then Premier of New South Wales, William McKell stated that nets were ‘quite valueless’ in terms of public safety.
He further went onto say, ‘Worse, it would possibly lull the public into a false sense of security, leading to diminished watchfulness and possibly tragedy." This was 70 years ago and scientists continue to echo these sentiments today, to no avail, as politicians with no experience in this area continue to make emotive, knee jerk and illogical decisions to shark mitigation.
The Queensland model has wiped out over 85,000 marine animals, with the majority being non target species such as whales, dolphins, reef sharks, dugongs, turtles and rays and now NSW will be further adding to the annihilation of our precious marine life off our coasts. No longer will we see pods of dolphins swimming freely off the NSW coast, they will be running a gauntlet of dolphin killing meshing devices.
With a humpback population on the rise, so too will be the entanglements of these protected species, just like off QLD this year with over 10 entanglements this year and there will be more to come, which also puts the rescuers lives at risk as they try to disentangle the whales.
Premier Baird needs to listen to the words of former Premier McKell, and drop this insane approach to shark mitigation, as nets are not a barrier, and are merely a false sense of security that wipe out tens of thousands of marine life and put human lives further at risk.
In 2016, with so many modern day smart and innovative shark mitigation systems and products, we no longer have to choose between keeping people safe or protecting our precious marine life, we can do both,” said Sea Shepherd Australia Managing Director Jeff Hansen.
Original article: http://www.seashepherd.org.au/news-and-commentary/news/sea-shepherd-slams-baird-s-1940-s-backwards-approach-to-saving-lives-merely-another-false-sense-of-security.html
The federal government is considering changes to Australia’s marine reserves to implement a national system. This week The Conversation is looking at the science behind marine reserves and how to protect our oceans.
While academics often focus on biodiversity objectives for marine parks, the public and political debate tends to come down to one thing: fishing.
When former federal MP Rob Oakeshott cast one of the deciding votes in support of the Commonwealth marine parks plan in 2013, he explained that he believed they benefit fisheries. The federal government has also emphasised the benefit of marine parks to fisheries production.
There’s also an academic debate. When a study showed that the Great Barrier Reef marine park had harmed fisheries production, there was a passionate response from other experts. This is despite advocates arguing that reserves are primarily about biodiversity conservation, rather than fishing production.
Clearly, fishing is a hot issue for marine parks. So what does the science say?
The proposed benefits to fisheries from marine parks include: protection or insurance against overfishing; “spillover”, where larvae or juveniles from the parks move out and increase the overall production; habitat protection from damaging fishing gear; and managing the ecosystem effects of fishing such as resilience against climate change.
Marine parks regulate activities, mainly fishing, within a specified area. They come in a variety of categories. Some allow fishing, but the most contentious are “no-take” marine parks.
Fishery managers also sometimes close areas of the ocean to fishing. This is different to how no-take marine parks work in two ways: the legislative authority is different (being through fisheries rather than environmental legislation); and the closures usually target a specific fishery, whereas no-take marine parks usually ban all fishing.
Fishery closures, rather than no-take marine parks, are usually applied to protect special areas for particular fish, such as spawning sites or nursery areas. They are also used to protect habitats, such as in the case of trawl closures, which allow the use of other gear such as longlines in the same location.
Fisheries legislation bans damaging fishing gear outright, while benign gears are allowed. In contrast, no-take marine parks tend to exclude all gear types.
Neither marine parks nor fishery closures regulate the amount of catch and fishing effort. They only control the location. Commercial fishers take most fish caught in Commonwealth waters and most of this is limited by catch quotas.
When a no-take marine park closes an area to fishing, fishers and their catch are displaced into other areas of the ocean. This occurs for all types of fishing, including recreational fishing. Recreational fishers displaced by marine parks don’t stop fishing, they just fish somewhere else – and the same number of fishers are squeezed into a smaller space.
Marine parks increase the intensity of fishing impacts across the wider coast, which is an uncomfortable outcome for marine park advocates. Modelling of Victorian marine parks showed that displaced catch would harm lobster stocks and associated ecosystems, and was counterproductive to their fishery management objective of rebuilding stock.
Because ecosystems don’t respond in predictable ways, depletion of fish stocks from the fishing displaced from marine parks could lead to severe ecosystem outcomes.
For this reason, a second and separate management change is often needed after marine parks are declared, which is to reduce the number of fishers and fish caught to prevent risk of impacts from the park.
Controlling how many fish are caught (which is what traditional fisheries management does) has substantially more influence on overall fish abundance than controlling where fish are caught with parks, as shown recently on the Great Barrier Reef.
Commonwealth fisheries catch quotas are routinely reduced if a fishery harms the sustainability of the marine environment. There’s no compensation to fishers, so there’s no cost to the public, other than a possible reduced supply of fish.
Catches can also be reduced to manage fishing displaced by marine reserves and the outcome is identical except in terms of the public cost. Creation of the Great Barrier Reef Marine Park led to over A$200 million in payments to displaced fishers. Another publicly funded package is planned for the Commonwealth marine reserves.
Marine parks also have high recurring public cost because boundaries need to be policed at sea. Catch quotas can be policed at the wharf, with compliance costs fully recovered from industry.
Evidence of a benefit to fisheries from marine parks is scarce. However, there are some clear examples of fishing displacement that is so minor that there has been an overall increase in fish inside and outside the park.
These examples show that marine parks can sometimes benefit fish stocks, the fishery and also the overall marine ecosystem. However, these examples come from situations where traditional fishery management has not been applied to prevent overfishing.
This is consistent with modelling of marine parks that shows they only increase overall fish populations when there has been severe overfishing. This generally means that if there’s already effective traditional fisheries management, marine reserves cannot benefit fish stocks and fisheries, or restock fish outside the reserve (spillover) (see also here).
In jurisdictions where fisheries management is lacking, any regulation, including through marine reserves, is better than nothing. But this isn’t the situation with Australia’s Commonwealth fisheries where harvest strategies are used and overfishing has been eliminated.
The conclusions from modelling of marine reserves mean that the areas of the reserves that limit fishing would be expected to reduce fishery production and harm our ability to contribute to global food security.
The Coral Sea marine reserve, in particular, represents an area with known large stocks of fish, especially tuna, that could be harvested sustainably. Limiting fishing in the Coral Sea eliminates any potential for these resources to help feed Australians or contribute to global food supplies.
The potential sustainable, ecologically acceptable harvest from the Coral Sea is unknown, so we don’t know the full scale of what’s being lost and how much the recent changes reduce this problem, although Papua New Guinea sustainably harvests 150,000-300,000 tonnes of tuna in its part of the sea.
Allowing fishing doesn’t mean the oceans aren’t protected. Existing fisheries management is already obliged to ensure fishing doesn’t affect sustainability of the marine environment.
4 Oct 2016
New South Wales Premier Mike Baird has this week announced a plan for a six-month trial of shark nets off the beaches of northern NSW. This would extend the state’s shark net program from the 51 beaches currently netted between Wollongong and Newcastle.
The announcement was triggered by Wednesday’s shark accident, in which a surfer received minor injuries from a shark bite at Sharpes Beach, Ballina.
The decision marks a turn-around in Premier Baird’s position on sharks. For over a year he has acknowledged the importance of addressing the issue, and has adopted a measured, long-term, non-lethal approach to managing shark hazards. Specifically, the NSW government has, in the last year, allocated funding and resources to non-lethal strategies including surveillance, research and education.
Killing sharks has been highly controversial in Australia in recent years, and in NSW shark nets have been a focus of ongoing, highly polarising debate.
The decision to introduce shark nets in the state’s north invites us to revisit some common misunderstandings about this strategy.
First, there is wide misunderstanding about what shark nets are and what they do. The nets used in the NSW Shark Meshing (Bather Protection) Program do not create an enclosed area within which beach goers are protected from sharks.
They are fishing nets, which function by catching and killing sharks in the area. Nets are 150 m long, 6 m deep, and are suspended in water 10-12 m deep, within 500 m of the shore.
Second, whether shark nets work is still up for debate. Shark nets have been used in NSW since 1937. Since then, the number of netted beaches, methods for deploying nets, and data collection and record-keeping methods have changed, and data sets are incomplete.
Our use of the beach and ocean has also changed dramatically. There are more people in the water, in new areas, and we’re using the ocean for different activities. At the same time, our observation of sharks and emergency response have improved dramatically.
The suggestion that nets prevent shark accidents is an oversimplification of a complex story, a misrepresentation of both technology and data, and it misinforms the public.
And finally, shark nets cannot be a long-term solution. They are out-dated technology based on outdated thinking, developed 80 years ago.
They go directly against our international responsibility to protect threatened species (under the International Union for the Conservation of Nature and our own Environment Protection and Biodiversity Conservation Act), and our national priorities for protecting marine environments and species, including several shark species.
We know that shark nets in NSW kill on average at least 275 animals per year (measured between 1950 and 2008), and that the majority of animals killed pose no threat to people. We can do better than this.
Right now we have an opportunity in NSW to learn from recent experiences in Western Australia. In 2012, the WA government, under Premier Colin Barnett, introduced hooked “drumlines” to kill sharks in an attempt to reduce the risk of shark bites. Like this week’s announcement by Premier Baird, that policy change was stimulated by a spike in shark accidents.
The response to the new policy was a highly-polarised debate and extraordinary public outcry, including two public protests at Perth’s Cottesloe Beach attracting 4,000 and 6,000 people, and protests in eleven other cities around the country, including 2,000 at Sydney’s Manly Beach.
The state’s Environmental Protection Authority received a record number of 12,000 submissions from scientific and other experts presenting reasons to cease the cull. The WA government heeded the EPA’s recommendation and cancelled the policy.
Our research with ocean users conducted during this period showed that perspectives are diverse (we surveyed 557 WA-based ocean-users using quantitative and qualitative research methods).
Among people who use the ocean regularly, some strongly oppose killing sharks; others are ambivalent; and a smaller number of people are in favour. People’s views and understandings are nuanced and carefully thought through.
However, within this group, the strategies for managing shark hazards that were most strongly supported were improving public education about sharks, and encouraging ocean users to understand and accept the risks associated with using the ocean. Other widely supported strategies included developing shark deterrents and increasing surveillance and patrols.
The most strongly opposed approaches were those that killed sharks including culling, proactive catch-and-destroy measures, baited drumlines, and shark nets.
In recent years we have been making good progress in Australia on public discussion and investment in more effective and ethical approaches for reducing shark bites. This week’s move to introduce an outmoded technology to the north coast promises to further divide the community.
We should continue to invest in developing new strategies that better reflect our contemporary understanding of marine ecosystems. Perhaps we also need to consider (temporarily) altering the way we use the ocean, avoiding areas of higher-than-usual shark sightings.
15 Oct 2016
A NEW species of spider crab has been named, more than 50 years after the first specimen was lodged at the Western Australian Museum.
Several specimens of the long-legged spider crab were collected during recent dredging surveys in WA's northwest, and upon detailed examination, they were found to look quite different to the one existing species of the genus, Paranaxia serpulifera.
After locating and examining 32 similar specimens amongst the WA Museum and Queensland Museum collections, and performing genetic testing, it was clear they belonged to a new species, says WA Museum curator of Crustacea and Worms, Andrew Hosie.
The crab was named Paranaxia keesingi, after CSIRO’s Dr John Keesing, in recognition of his contribution and commitment to the knowledge of WA biodiversity.
The earliest collected P. keesingi found in storage was collected in 1963 by Fremantle-based fishermen W. & W. Poole from Shark Bay. Many specimens are in a similar situation—waiting for someone to take notice and characterise them—according to Mr Hosie.
“Describing new species and ensuring that they are not an already known species, can be incredibly slow and painstaking work, requiring great patience and attention to detail,” Mr Hosie says.
One of the main reasons for the long time a specimen may remain undescribed is lack of available expertise, as museums generally do not have a scientist dedicated to every single group of animal, he says.
“We have to rely on experts at other museums for this material to be examined, and we routinely send specimens out for identification,” he says.
“But if the priorities and funding of external experts don’t line up with ours, then it can take a very long time before they are even identified as a new species, let alone described, named and published.” Secondly, Mr Hosie says specimens may not be suitable or there may not be enough information to describe them.
“If there is only one or a few specimens, or they are damaged, juvenile, only females, or only males—then naming and describing them may be postponed until there are enough specimens of suitable quality to provide a full description of the species,” he says.
Advancements in science also mean that species can now be distinguished at a genetic level to help tease apart ‘species complexes’ where there is a group of very similar looking species, Mr Hosie says.
“There are now new species described that were once considered regional variants or subspecies, but with the aid of genetic sequencing these are often shown to be distinct species.”
Paranaxia keesingi can be found as far south as the Houtman Abrolhos Islands and north into Indonesian waters off New Guinea as well as in northern Queensland and is recorded at depths of up to 175 metres.
Written by Teresa Belcher
First published on science network western australia: http://www.sciencewa.net.au/topics/fisheries-a-water/item/4309-new-spider-crab-named-50-years-after-its-discovery
11 Sep 2016
The global offshore oil and gas industry has installed a wide variety of infrastructure throughout our oceans, including tens of thousands of wells, thousands of platforms and many thousands of kilometres of seabed pipelines.
Many of these structures have been in service for several decades and are approaching retirement. The North Sea, for example, has more than 550 platforms and undersea production facilities, virtually all of which are set to be decommissioned in the next 30 years.
In Southeast Asia, the issue is even bigger: almost half of the region’s 1,700 offshore installations are more than 20 years old and approaching retirement.
After decommissioning and cleaning a platform, seabed structure or pipeline, its operators are faced with a choice: dismantle and remove it completely; leave it in place; or remove some of it while leaving the rest behind.
The choice depends largely on what is technically feasible, as well as what is desirable from an environmental, economic and societal perspective, and of course what is legally allowed.
The earliest relevant international law, the 1958 Geneva Convention on the Continental Shelf, requires the complete removal of disused marine infrastructure. But the United Nations Convention on the Law of the Sea, which has largely superseded it, is more lenient. It states that decisions should take into account “generally accepted international standards established … by the competent international organisation” – in this case the International Maritime Organisation (IMO).
The IMO’s 1989 guidelines allow structures to be left in place on a case-by-case basis. Due consideration must have been given to safety of navigation, rate of deterioration, risk of structural movement, environmental effects, costs, technical feasibility and risks of injury associated with removal.
The guidelines also refer to the possibility of “new use or other reasonable justification” for in situ disposal. This opens up some possibilities for how offshore platforms might take on a new life without being removed.
Europe has so far tended to favour complete removal of offshore infrastructure, in line with international law. Safely recovering these ageing and vast structures from harsh environments is technically challenging, and the industry has developed some impressive technology such as the Pioneering Spirit, a specialised vessel constructed to lift steel platforms from the North Sea.
Complete removal is expensive, both to oil and gas companies and the taxpayer. It also leaves operators facing the problem of what to do with the recovered material. While some parts of the topsides of platforms can be refurbished if structurally sound, most of the material is not reusable. Some elements can be recycled, but much of it will inevitably end up in landfill.
From an environmental perspective, the notion of returning the seabed to its original state is undoubtedly born of the right intentions. But when engineered structures have been part of the marine environment for several decades, might it do more harm than good to remove them?
Artificial reefs are often deliberately placed in our oceans to provide habitat for marine life or sites for recreational diving. But many offshore oil and gas structures also fulfil these functions – for instance, by providing breeding sites for fisheries. Removing them might therefore harm these ecosystems.
Despite this, European law only allows artificial reefs to be created from new materials, rather than decommissioned infrastructure.
The United States, which has national laws that allow offshore infrastructure to be left in place, has an established a “rigs to reefs” program administered through the Bureau of Safety and Environmental Enforcement. Under this program, more than 400 decommissioned rigs have been converted to permanent reefs since 1986.
Rigs cannot simply be left to rust in the ocean; projects like this require rigorous assessment before being approved. But the assessment criteria are different and typically less stringent than for the earlier production phase of the rig’s life, largely because there is no longer a risk of spills after decommissioning.
During their initial operating life, marine structures and pipelines must meet strict criteria that limit movement or deformation. This is to ensure that machinery operates correctly and containment systems do not release hydrocarbons into the marine environment. Strict regulations also apply to the removal of hydrocarbons and residues from the system during decommissioning and cleanup.
But once decommissioned, all that is required is that the structure is sufficiently stable on the seabed and will not break apart in ways that would harm the environment or pose a danger to shipping.
Leaving disused infrastructure in the ocean also raises the critical question of who bears ultimate responsibility for it. Should ownership stay with the original operator, or be transferred to the government? This raises issues of liability for any damage that might occur in the future, and who should bear that risk remains a live question for debate and discussion.
Australia’s offshore oil and gas industry is less mature than those in Europe and the United States. As a result, the fate of decommissioned offshore infrastructure is still an emerging issue.
Australia’s current regulations favour complete removal. But the National Offshore Petroleum Safety and Environmental Management Authority is exploring the possibility of supporting an in situ decommissioning policy.
This would involve amending the law to allow certain new uses, as well as to resolve issues of decommissioning standards, safety and risk, liability and ownership. The lack of any established practice gives Australia a unique chance to show innovative leadership on this issue.
Developing an Australian version of the “rigs to reefs” policy would require input from engineers, natural scientists, environmental managers, oil and gas economists, lawyers and others, to work out precisely what is possible and preferable in different locations.
There is little doubt that pressures on the ocean environment will only increase. Growing populations will increase demand on fisheries and probably lead to the development of large offshore aquaculture projects, as well as escalation of shipping and ocean-based transport. Similarly, the demand for energy may drive broad implementation of wave energy and other marine renewables.
With the growing variety of industries set to use the oceans in future, now is the right time to take a wide-ranging look at how best to handle the structures that are already there.
Scientists are looking for physical vulnerabilities in the coral-eating Crown-of-Thorns Starfish (COTS) in order to mitigate their harmful impacts on coral reefs when in plague numbers. In their pursuit of an Achilles heel, scientists have focussed on the animal’s ability to perceive its environment through its senses. Research has already demonstrated that adult COTS have a well-developed sense of smell, touch and taste. Better understanding these aspects of COTS biology may lead to new methods to either disperse or attract them in order to control their numbers.
Recently, research collaborators working with AIMS scientists discovered that adult COTS also have a well-developed sense of sight. At the end of each of their 12 to 15 arms there is an eye which can form rudimentary images of its immediate environment. In effect, a COTS has ‘surround vision’, and can detect large stationary objects against a blue ocean background. Although they are not capable of high resolution image formation, they are capable of seeing where a suitable hideout might be to avoid open areas and minimise exposure to predators.
The study also found that COTS can see slow moving objects, such as the predatory snail, the Pacific triton (Charonia tritonis). Using their sense of sight, COTS are capable of detecting an approaching object, which is to its benefit as it could be it primary predation, the triton snail. If needed, they can coordinate their thousands of tube feet to escape from the approaching object – which might be planning on making a meal of it.
11 Aug 2016
Source Australian Institute of Marine Science (AIMS) 2016
Controlling repeated outbreaks of the coral-eating Crown-of-Thorns Starfish (COTS), Acanthaster planci, is one of the greatest challenges facing resource managers of the Great Barrier Reef (GBR).
COTS, together with cyclones, are responsible for more than half of all coral cover loss on the GBR. As one of several lines of investigation into COTS population management, our researchers are taking a novel approach to the issue by examining the intriguing potential of a snail, the Pacific triton, a natural enemy of COTS.
The Pacific triton (Charonia tritonis, also known as the “giant triton”) is a large marine snail that inhabits coral reefs throughout the Indo-Pacific region. They are rare; historical evidence of harvesting levels is scant, however scientists speculate that overharvesting of the snails for the meat and shell has led to threatened status throughout their range. As such, tritons have been protected on the GBR for decades.
Their diet consists primarily of starfish, but will also prey on other echinoderms such as sea cucumbers. Like other predatory marine snails, tritons have a very well developed sense of smell and can hunt their starfish prey by scent alone. Although tritons will prey on several species of starfish, they are particularly fond of COTS. Tritons are one of the few predators of adult COTS as they are seemingly unaffected by their ‘crown-of-thorns’ - hundreds of sharp spines and toxic saponin coating which otherwise acts as a very powerful deterrent against potential predators.
However, while tritons prefer the often-abundant COTS, they only eat a few per week. With COTS populations on the GBR estimated to be in the many millions, the combination of this low predation rate and the rarity of triton individuals means that they have limited impact on reducing COTS numbers through predation alone.