Saving Seafood

BP oil disaster might have hurt Bluefin tuna rebuilding, study says

October 3, 2016 — The release of 4 million barrels of oil in the 87 days following the BP Deepwater Horizon explosion in April 2010 occurred just as Atlantic bluefin tuna had returned to the Gulf of Mexico to spawn, and a small but significant percentage of the adult fish and their eggs and larvae were likely exposed to the toxic oil, according to a new study announced Friday (Sept. 30).

The study led by scientists with NOAA’s National Marine Fisheries Service and Stanford University concludes that the oil cumulatively covered 3.1 million square miles where fish, eggs and larvae were present in the weeks immediately after the accident.

When combined with other stressors affecting this species of tuna — including overfishing and warming seas caused by climate change — the addition of the oil’s impact “may result in significant effects for a population that shows little evidence of rebuilding,” the study published in Nature: Scientific Reports concluded.

The study, funded by the Natural Resource Damage Assessment for the BP spill required under the federal Oil Pollution Act, made use of computer modeling based on information gathered from 16 years of electronic tagging of 66 tuna that kept track of individual fish locations, temperatures and oscillating diving patterns. The information was compared with satellite observations of the breadth of oil from the spill on the surface of the Gulf to estimate the potential impacts.

Barbara Block, a Stanford professor of marine scientists and expert on Atlantic bluefin tuna, said in a Friday interview that the tagging program took advantage of earlier tagging information that indicated many of the Gulf-spawning tuna migrate back and forth from the Gulf of St. Lawrence in Canada. Researchers captured adult tuna in Canada and installed the tags. When the fish returned to Canada a year later, the tags dropped off and were collected, and their data was added to a long-term database on fish movements.

The information collected from the tags helped the scientists confirm their theories about the spawning habits of the huge fish, which can weigh as much as 1,000 pounds at maturity, and begin reproducing about 10 years after birth.

Read the full story at the New Orleans Times-Picayune

How In Trouble Are Bluefin Tuna, Really? Controversial Study Makes Waves

March 9, 2016 — Bluefin tuna have been severely depleted by fishermen, and the fish have become a globally recognized poster child for the impacts of overfishing. Many chefs refuse to serve its rich, buttery flesh; many retailers no longer carry it; and consumers have become increasingly aware of the environmental costs associated with the bluefin fishery.

But a group of scientists is now making the case that Atlantic bluefin may be more resilient to fishing than commonly thought — and perhaps better able to rebound from the species’ depleted state. In a paper published Monday in the journal Proceedings of the National Academy of Sciences, the researchers suggest that fishery managers reassess the western Atlantic bluefin’s population, which could ultimately allow more of the fish to be caught.

The 10 co-authors, most of whom are scientists with the National Oceanic and Atmospheric Administration, say they’ve all but confirmed that bluefin tuna spawn in an area of the Atlantic Ocean previously suspected but not known to be a breeding ground. Not only that; the tuna spawning in this area off the Atlantic Coast are much younger and smaller than the age and size at which it was previously believed the fish become sexually mature, according to the scientists.

This, their paper claims, would make the western Atlantic bluefin tuna “less vulnerable to overexploitation and extinction than is currently estimated.”

But the study is controversial. Several tuna researchers we spoke with warned that the results are preliminary, and it’s much too soon to use them to guide how fisheries are managed

Read the full story from NPR