Atlantic bluefin tuna, which are drastically overfished, compound their danger by crossing the ocean into alien fishing territory, a new study in the journal Science concluded. There are two separate bluefin populations: one in the Gulf of Mexico, one in the Mediterranean. By analyzing ear bones, scientists found that fish from each population cross the Atlantic into the other’s region. That means that Gulf bluefin are caught not only in North American waters but also in the east Atlantic and the Mediterranean, where aggressive illegal fishing led the European Union to end this year’s season two weeks early. The crisscrossing also means that Mediterranean bluefin are double-counted in the Gulf population — although the researchers determined that commercial catches in that region are almost exclusively Gulf tuna.
The findings prompted conservationist Carl Safina to call for a moratorium on bluefin fishing in American waters; a fisheries spokeswoman for the U.S. National Oceanic and Atmospheric Administration responded that the study underscores the need for stricter European fishing controls.