Help for the bluefin tuna

	Giant Atlantic bluefin tuna from Prince Edward Island, Canada. Click here for more information.

A new discovery that both western bluefin tunas, born in the Gulf of Mexico, and eastern bluefin tunas, born in the Mediterranean Sea, mix together in the Atlantic Ocean during their adolescence has the potential to spark revisions to conservation efforts and help repopulate the species, researchers report in the Oct. 2 issue of Science. Currently, populations of both Atlantic bluefin tuna are in a very vulnerable state, and current conservation efforts do not seem to be working. Jay Rooker and colleagues determined the birthplaces of many tuna populations by comparing the carbon and oxygen isotope ratios in the fishes’ inner ears, and found that, after mixing together in the Atlantic, eastern and western bluefin tuna populations return to their places of birth to spawn. This finding reveals that the fish cross international jurisdictions, and the researchers suggest revising international conservation rules in light of this discovery. Rooker and colleagues also say that the waters around the Gulf of Maine and St. Lawrence act as a refuge for mature adult tunas from the western population, which is in worse shape than the eastern population, and that this discovery should be incorporated into the new guidelines as well. Finally, the authors indicate that a more conservative exploitation of the fish, including the elimination of bycatch in the Gulf of Mexico, is required for the recovery of western bluefin tunas.

ARTICLE #20: "Natal Homing and Connectivity in Atlantic Bluefin Tuna Populations," by J.R. Rooker; R. Schloesser at Texas A&M University in Galveston, TX; D.H. Secor at University of Maryland Center for Environmental Science in Solomons, MD; G. DeMetrio at University of Bari in Valenzano, Italy; B.A. Block at Stanford University in Pacific Grove, CA; J.D. Neilson at St. Andrews Biological Station in St. Andrews, NB, Canada.