Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New study provides comprehensive view of the status of Atlantic bluefin tuna

12.12.2011
Overfishing in the Mediterranean Sea is felt in North American waters

A new model built around biological data from electronic tags, ear bone microchemistry and fisheries catch data for Atlantic bluefin tuna indicates fishing on one side of the Atlantic influences the other side.

Bluefin populations on both sides of the Atlantic Ocean have declined precipitously since 1950, according to the study published today in the peer-reviewed online journal PLoS ONE. The model estimates the number of Atlantic bluefin tuna remaining in the ocean and projects future population sizes based on alternative management scenarios.

The new model is revolutionary in its ability to account for population overlap (mixing) of this highly migratory animal on the North Atlantic foraging grounds.

Two or more Atlantic bluefin populations are currently recognized by ICCAT, the international commission charged with conserving highly migratory fishes like bluefin in the Atlantic. A western population spawns in the Gulf of Mexico and is primarily fished by North Americans, and an eastern population spawns in the Mediterranean Sea and is fished by European and North African fishers, along with high seas longliners from multiple nations.

The PLoS ONE study indicates that since 1950 adult bluefin tuna numbers have declined by as much as 83% in the Gulf of Mexico spawned western Atlantic population, and 67% in the Mediterranean spawned eastern Atlantic population.

This innovative model incorporates new biological data such as the extensive migrations recorded on electronic tags and the information on natal origin lodged like a birth certificate in the minerals of ear bones, in order to account for the intricate movements on a seasonal scale. Bluefin can live up to 35 years of age, and reach 1500 lbs in size. Tag tracking data indicate that individual bluefin can rapidly move between western and eastern management regions but then separate and return to distinct spawning areas.

The Mediterranean population was modeled with a significantly lower age to first reproduction or maturity than the Gulf of Mexico population, increasing the resilience of the former population. The combination of biological and mathematical inputs has shown a significant subsidy exists when the larger Mediterranean population moves into western waters to feed.

"Current population models assume that a fish caught in the West Atlantic was born in the west, and a fish caught in the east was born in the east," said senior author Dr. Murdoch McAllister of the University of British Columbia. "We now know that upwards of 50% of bluefin caught in some western fisheries were spawned in the Mediterranean, and incorrect assignment of these fish biases assessments and may compromise recovery efforts of this valuable species." High levels of fishing in the Mediterranean Sea, including pirate fishing, resulted in the highest fishing mortality on record for the species between 1998 and 2007. Importantly, the model shows that this egregious overfishing in the East depleted not just the eastern population but the western one as well. The eastern catch of bluefin tuna has been cut by approximately half since 2007 so this trend may reverse in the coming years.

The model estimates that eastern bluefin tuna can recover relatively quickly with perfect adherence to current regulations. However, significant illegal overfishing continues to be documented and threatens the recovery of fish in both the eastern and western Atlantic. Recovery of the depleted western Atlantic bluefin tuna population will take more than 15 years under current fishery regulations.

"This model presents a challenge to the global community responsible for the management of Atlantic bluefin tuna, both from a regulatory and scientific perspective," said senior author Dr. Barbara Block of Stanford University. "If regulations are not enforced, population recovery will stall. If we don't account for population overlap in assessments, the estimates upon which we base management will be flawed."

Funding for this study was provided by the Lenfest Ocean Program, Tag-A-Giant Foundation, the Canadian Fisheries and Oceans International Governance Strategies Fund, the Monterey Bay Aquarium Foundation, and the National Oceanographic and Atmospheric Administration.

For more information, visit www.tagagiant.org.

For information, contact

University of British Columbia: Murdoch McAllister, (604) 822-3693; m.mcallister@fisheries.ubc.ca

Stanford University: Barbara Block, (831) 655-6236; bblock@stanford.edu

Murdoch McAllister | EurekAlert!
Further information:
http://www.fisheries.ubc.ca
http://www.tagagiant.org

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: 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...

Im Focus: New nanomaterial can extract hydrogen fuel from seawater

Hybrid material converts more sunlight and can weather seawater's harsh conditions

It's possible to produce hydrogen to power fuel cells by extracting the gas from seawater, but the electricity required to do it makes the process costly. UCF...

Im Focus: Small collisions make big impact on Mercury's thin atmosphere

Mercury, our smallest planetary neighbor, has very little to call an atmosphere, but it does have a strange weather pattern: morning micro-meteor showers.

Recent modeling along with previously published results from NASA's MESSENGER spacecraft -- short for Mercury Surface, Space Environment, Geochemistry and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

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

Conference Week RRR2017 on Renewable Resources from Wet and Rewetted Peatlands

28.09.2017 | Event News

 
Latest News

A single photon reveals quantum entanglement of 16 million atoms

16.10.2017 | Physics and Astronomy

The melting ice makes the sea around Greenland less saline

16.10.2017 | Earth Sciences

On the generation of solar spicules and Alfvenic waves

16.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>