US: Bluefin tuna probably OK after BP oil spill

Dec 04, 2011 By SETH BORENSTEIN , AP Science Writer

(AP) -- Last year's BP oil spill probably won't push the troubled bluefin tuna population in the Gulf of Mexico over the edge as some scientists had worried, a federal analysis shows.

Of all the potential damage from the 172-million-gallon (651-million-liter) spill in April 2010, scientists had been most concerned about how the oil spill would harm an already overfished species of large tuna. That's because about one-fifth of the spawning habitat where the Gulf's baby tuna were living was coated with oil, according to satellite records. Tuna less than a year old are most vulnerable to pollution.

An analysis by the , using two different projections from computer models, says that at most, such a spill probably would result in a 4 percent reduction in future spawning of the fish, but probably far less.

Bluefish tuna is considered one of the Gulf's signature species. A summit that begins Monday in Houston will examine the Gulf's health, including the government's restoration plans and the tuna's fate.

"It appears so far that the impact on the larval population is relatively small," said Clay Porch, director of sustainable fisheries for NOAA's Southeast Fisheries Science Center in Miami.

The agency's analysis, which was mentioned in two pages of a 114-page government update on overall tuna health released in May, is based on an assumption that 1 in 5 baby tuna was killed or unable to reproduce in the future because that's the size of the spill in the spawning area.

That 20 percent potential loss of year-old tuna translates to 4 percent of the overall tuna population in the future. Overall population figures also have to factor in the fact that in general many baby tuna at that age die naturally.

But that is probably way too high a figure, Porch said in an interview.

Instead of 20 percent of baby tuna being harmed, more recent analysis yet to be published said it should be 11 percent or maybe even 5 percent, he said. Those figures should be reduced even more for the overall future population of tuna, down nearer to 2 percent.

At most that number should be 1 in 9 or even in 1 in 20 deaths of baby tuna, and that's only the effect on one year for the long-lived tuna.

Those smaller figures are based on larval surveys that have not been released publicly because of a potential court case with over damages from the spill, and more simulations "that are conditioned on real data," Porch said.

Porch said it's unlikely that the effect on tuna stock would hit 4 percent and "it is not an additional major source of stress" on the overall population of the bluefin tuna in the Gulf. Other work on baby tuna health will be published in peer reviewed science journals.

But that's only the young. So far NOAA doesn't know how the spill affected adults and whether adults of all ages were killed or made infertile in massive numbers that could have a bigger effect on the overall population than the oiling of one year's worth of young, Porch said.

Boris Worm, a fisheries professor at Dalhousie University in Canada who has warned of problems with tuna populations in the past, said the NOAA figures are within the yearly variations of mortality for tuna.

"So it will be a bad year, but not a catastrophic year," Worm said. "This wouldn't push them over the brink."

Former NOAA chief scientist Sylvia Earle, a renowned ocean explorer who has campaigned against overfishing of tuna, isn't convinced that bluefin tuna weathered the oil slick.

"I think it's too early to celebrate a possible greater survival than had been predicted. These are, after all, models," Earle said. "The truth is we don't have enough information to be able to clearly say one way or another what happened to the 2010 class of baby tuna."

Gulf scientists have wondered for months about the health of the bluefin , said Larry McKinney, executive director of the Harte Research Institute for Studies at Texas A&M University in Corpus Christi.

"They are sentinel species that gives us an idea of the health of the open ocean, where we don't know a lot," McKinney said.

---

Online:

NOAA's status of the : http://tinyurl.com/bmwoauf

NOAA's Southeast Fisheries Science Center: http://www.sefsc.noaa.gov

Gulf summit: http://www.sgmsummit.org

Harte Research Institute for the Gulf of Mexico Studies: http://www.harteresearchinstitute.org

Explore further: Parks Service bans drones over Appalachian Trail

not rated yet
add to favorites email to friend print save as pdf

Related Stories

US keeps bluefin tuna off endangered list

May 27, 2011

The United States on Friday rejected calls to protect Atlantic bluefin tuna as an endangered species, saying that while it was worried about overfishing it did not fear imminent extinction.

Britain steamed over tuna rules

May 10, 2007

Britain's fisheries minister Ben Bradshaw is calling on the European Union to ban fishing for bluefin tuna in the Mediterranean Sea.

Overfishing may lead to tuna extinction

Nov 18, 2005

Some scientists fear the bluefin tuna, Japan's unofficial national dish, is being caught in such numbers its commercial extinction is looming.

Tuna nearly fished to extinction

Sep 15, 2005

Australian officials say one of that nation's most valuable fish -- the southern bluefin tuna -- is facing extinction.

Recommended for you

Genetically tracking farmed fish escaping into the wild

Aug 20, 2014

European sea product consumption is on the rise. With overfishing being a threat to the natural balance of the ocean, the alternative is to turn to aquaculture, the industrial production of fish and seafood. ...

France fights back Asian hornet invader

Aug 20, 2014

They slipped into southwest France 10 years ago in a pottery shipment from China and have since invaded more than half the country, which is fighting back with drones, poisoned rods and even chickens.

Tide turns for shark fin in China

Aug 20, 2014

A sprawling market floor in Guangzhou was once a prime location for shark fin, one of China's most expensive delicacies. But now it lies deserted, thanks to a ban from official banquet tables and a celebrity-driven ...

Manatees could lose their endangered species status

Aug 19, 2014

About 2,500 manatees have perished in Florida over the last four years, heightening tension between conservationists and property owners as federal officials prepare to decide whether to down-list the creature to threatened ...

User comments : 0