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 Global threat to primates concerns us all
19.01.2017 | Deutsches Primatenzentrum GmbH - Leibniz-Institut für Primatenforschung

nachricht Reducing household waste with less energy
18.01.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH

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: Quantum optical sensor for the first time tested in space – with a laser system from Berlin

For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.

According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

New technology for mass-production of complex molded composite components

23.01.2017 | Process Engineering

Quantum optical sensor for the first time tested in space – with a laser system from Berlin

23.01.2017 | Physics and Astronomy

The interactome of infected neural cells reveals new therapeutic targets for Zika

23.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>