Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Reef Sharks Threatened by Overfishing

07.12.2006
A study by Australian scientists has warned that coral reef shark populations on the Great Barrier Reef are in the midst of a catastrophic collapse.

The research by William Robbins and colleagues, based at James Cook University and the ARC Centre of Excellence for Coral Reef Studies, found that grey reef shark numbers had already declined to around 3% of unfished levels, and are currently declining so fast that they could collapse to one thousandth of their unfished levels within 20 years if current conditions continue.

Whitetip reef sharks fared little better: they are currently at 20% of unfished levels, and are headed towards 5% within two decades.

The study is the first of its kind to combine direct underwater counts of shark abundance with mathematical models that project future population trends based on information about reef sharks’ current survival, growth and reproductive rates.

“Our research indicates that current reef shark abundances and levels of fishing pressure are simply not sustainable. Reef sharks are effectively on a fast track to ‘ecological extinction’ – becoming so rare that they will no longer play their part in the ecology and food web of the reef,” says Robbins, the study’s lead author.

“It also suggests that immediate and substantial reductions in fishing pressure will be needed to give threatened populations any chance of recovery,” he added.

The researchers also compared shark abundances in reefs that had been zoned for different levels of fishing in the decades preceding the study. They found that some types of no-take zones had worked very effectively for reef sharks, but that others had not. In particular, reef shark abundances in “pink zones”, which are strictly policed no-take zones that require special permits to enter, were as large as on oceanic reefs with virtually no shark fishing. In contrast, shark abundances in “green zones”, where illegal fishing is much harder to prevent, were similar to abundances in legally fishable areas.

“Reef sharks mature late in life, and, like many whales and dolphins, produce very few offspring,” notes Mizue Hisano, a co-author of the study. “This makes it hard for them to bounce back from even low levels of fishing, such as poaching in green zones.

The study highlights the importance of ensuring high compliance with no-take regulations. “The recent re-zoning of the Great Barrier Reef, with its increased emphasis on building support for no-take zones among reef users, is an important step to increase the effectiveness of no-take areas,” says Dr Sean Connolly, another of the study’s authors.

“However, these efforts need to be combined with realistic limits on shark fishing for the ecosystem as a whole. Because shark fishing is intensifying, the population collapses that we have identified are likely to accelerate if we do not take action now.”

It was especially disturbing that a collapse in shark populations had occurred on Australia’s Great Barrier Reef, says Hisano. “The Great Barrier Reef is widely regarded as one of the world’s best-managed reef ecosystems. This means the situation may well be even more serious on reefs elsewhere in the world.”

The team’s report “Ongoing collapse of coral reef shark populations” appears in this week’s issue of Current Biology.

Article
Robbins, WD; Hisano, M; Connolly, SR and Choat, JH. “Ongoing Collapse of Coral-Reef Shark Populations”. Current Biology 16, 2314–2319.
More information:
William Robbins, School of Marine and Tropical Biology, James Cook University, 07 4781 5574 (after Dec 8 only)
Dr Sean Connolly, ARC Centre of Excellence for Coral Reef Studies & James Cook University, 07 4781 4242 or 04 1942 2815
Mizue Hisano, ARC Centre of Excellence for Coral Reef Studies & James Cook University, 07 4781 5725
Jenny Lappin, ARC Centre of Excellence for Coral Reef Studies, 07 4781 4222
Jim O’Brien, James Cook University Media Office, 07 4781 4822

Sean Connolly | EurekAlert!
Further information:
http://www.coralcoe.org.au/

More articles from Ecology, The Environment and Conservation:

nachricht Waste in the water – New purification techniques for healthier aquatic ecosystems
24.07.2018 | Eberhard Karls Universität Tübingen

nachricht Plenty of habitat for bears in Europe
24.07.2018 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

First study on physical properties of giant cancer cells may inform new treatments

14.08.2018 | Life Sciences

Tiny Helpers that Clean Cells

14.08.2018 | Life Sciences

Algorithm provides early warning system for tracking groundwater contamination

14.08.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>