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Global decline of tuna populations exaggerated

University of Hawaiʻi at Mānoa
John Sibert, (808) 956-4109
Pelagic Fisheries Research Program
Posted: Apr 29, 2005

HONOLULU — Recent claims that Pacific tunas are disastrously overfished are wrong, according to a new study by five distinguished international fisheries scientists published this week in the journal Nature.

The new study finds that conclusions from a 2003 Nature paper claiming that global stocks of tuna would soon disappear were based on flawed methods of analysis using only a small portion of the available data. The new study uses data that cover all the main habitats of tropic tuna and all the major countries that engage in large-scale fishing, including Japan, South Korea, Taiwan, and the United States. The earlier Nature paper used only a small portion of the data from Japan.

Headed by Dr. John Hampton of the Secretariat of the Pacific Community (SPC), an international organization formed by the Pacific island nations to provide assistance with development issues including fisheries, the new study also involved scientists from three other organizations recognized internationally for their work on fisheries—the University of Hawaiʻi; the Inter-American Tropical Tuna Commission, an international scientific and regulatory body formed by the 14 nations concerned with the conservation and management of tuna fisheries in the eastern Pacific Ocean; and the National Oceanic and Atmospheric Administration, the U.S. government body charged with fisheries science and management.

The new study also uses data analysis methods that are widely recognized among fisheries scientists to provide the best estimates of changes in fish populations. Using better data and methods, the new study finds that some tropical tuna species are indeed threatened, but that many species are not. For example, southern albacore tunas, often sold as canned white meat tuna, remain highly abundant and do not risk disappearing in the next two to three decades, as was claimed in the earlier analysis.

The new findings are important because incorrect conclusions could lead to flawed fisheries management decisions. For example, were fisheries management bodies to severely restrict catches of southern albacore, food supplies could be hurt unnecessarily and an economically important industry could be undermined.

"This new study provides a valuable lesson about the importance of using all available data and conducting analysis using the best possible methods," says Hampton, chief of the Oceanic Fisheries Programme at the SPC. "Because the goal of fisheries science is to enable sustainable management of this important world resource, getting the numbers right is critical. Incorrect numbers can lead to bad management decisions that in turn lead to job loss and reduced food supplies."

The new findings are also important because, for the first time in the 50-year history of high-seas tuna fishing, regulation of the fishery is now legally possible. In December 2004, 19 countries, including the United States, signed an international treaty creating the Western and Central Pacific Tuna Commission. Together with the Inter-American Tropical Tuna Commission, the new Commission will manage tuna fisheries across the entire Pacific Ocean. The accuracy of stock assessments are thus of increased importance because there is now an ocean-wide regulatory body.

Further information on the abundance of tunas and errors in the 2003 article is available at:

Author contact information:

Dr. John R. Sibert, Manager, Pelagic Fisheries Research Program, University of Hawaiʻi,

Phone: (808) 956-4109; E-mail:

Dr. John Hampton, Oceanic Fisheries Programme, Secretariat of the Pacific Community,
BP D5, 98848 Noumea, New Caledonia

Phone: +687-26-20-00; E-mail:

Dr. Mark N. Maunder, Inter-American Tropical Tuna Commission,
La Jolla, California, 92037-1508

Phone: (858) 546-7027, E-mail:

Dr. Shelton J. Harley, Inter-American Tropical Tuna Commission,
La Jolla, California 92037-1508


Dr. Pierre Kleiber, National Marine Fisheries Service, Pacific Islands Fisheries Science
Center, Honolulu, Hawaii 96822-2396


Internationally recognized fisheries experts have also expressed concern over exaggerated claims of the global collapse of tuna stocks:

· Dr. Ray Hilborn, School of Aquatic Sciences and Fisheries, University of Washingon, E-mail:

· Dr. Keith Sainsbury, CSIRO Marine Resources, Australia, E-mail:

· Dr. Carl Walters, Fisheries Center, University of British Columbia, E-mail:

For more information, visit: