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 Preservation of floodplains is flood protection
27.09.2017 | Technische Universität München

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Osaka university researchers make the slipperiest surfaces adhesive

18.10.2017 | Materials Sciences

Space radiation won't stop NASA's human exploration

18.10.2017 | Physics and Astronomy

Los Alamos researchers and supercomputers help interpret the latest LIGO findings

18.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>