Researchers at Stanford University and Monterey Bay Aquarium said their study shows the United States and other nations must change how they manage Atlantic bluefin tuna fisheries.
"In my lifetime we've brought this majestic species to the doorstep of ecological extinction in the western Atlantic Ocean," said lead researcher Barbara Block of the study published in Nature. "We must, as an international community, start to act responsibly to ensure the future of this species."
The study, which tagged and tracked hundreds of fish, confirmed the North Atlantic is home to a western stock that spawns primarily in the Gulf of Mexico and an eastern stock that breeds in the Mediterranean Sea.
While both populations declined since the 1970s, the International Commission for the Conservation of Atlantic Tunas estimates the western stock has dropped 80 percent.
Researchers called on the commission to change its counting methodology and said commercial fishing limits should be imposed.