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[size=12pt]Researcher: Northern Gulf fish show signs of disease, but link to spill uncertain[/size]
Published: Sunday, October 09, 2011, 6:22 AM Updated: Sunday, October 09, 2011, 11:20 AM
By Ben Raines, Press-Register
MOBILE, Alabama -- The scientist leading a federal probe into concerns that the BP oil spill caused flesh-eating diseases to run rampant in the Gulf’s red snapper population said his research so far suggests that about 3 percent of fish suffered from some form of external disease.
But whether any of those fish were sickened by exposure to BP’s oil is a complicated question without an easy answer, said Steve Murawski, a biologist with the University of South Florida, who cautioned that his team is still in the process of examining a lot of data.
The vast majority of fish examined were fat and healthy, he said of the study funded by the National Marine Fisheries Service.
Murawski said more fish in the northern Gulf showed symptoms than along Florida’s west coast, and he said multiple species were affected.
“There is definitely something going on,” Murawski said. “If I had to guess, I saw a lot of what I would consider healing lesions, things that looked like the fish had a healing bruise. So, if the majority of them look like they are healing up, maybe we are on the other side (of the outbreak).”
Murawski also said he wouldn’t be surprised if it turned out that the percentage of Gulf fish exhibiting external sores or diseases like fin rot prior to the spill was similar to the percentage his team discovered during his massive, months-long sampling effort this summer.
The key problem, he said, is that no one ever tried to get a handle on how prevalent such diseases were prior to the spill.
Meanwhile, scientists on the lookout for signs of disease during a research cruise off Alabama last week found a robust Gulf of Mexico rippling with life.
Instead of the finding evidence of fish made sick by the BP spill, researchers encountered sperm whales, leatherback turtles, flying fish, sharks, dolphin and lots of healthy red snapper.
After catching and examining hundreds of fish — including snapper, amberjack, porgies and ruby red lips — the researchers failed to detect any sign of lesions or other abnormalities.
Sean Powers, a researcher with the Dauphin Island Sea Lab, said the lab has collected fish on dozens of research cruises between Apalachicola, Fla., and the Mississippi/Alabama line.
“We’ve examined more than 3,500 fish total. We’ve only seen one with any kind of ulcer,” said Powers “We’re not saying that disease is not in the population. We’re saying disease is a common, natural part of all biological populations.”
Murawski, who was previously the chief science adviser for the National Marine Fisheries Service, said there are only a few studies that explored the percentage of sick fish in a typical population. The best, he said, was conducted in the 1980s in the northeast, along the Atlantic Coast. About 1 percent of the 85,000 fish in that study had lesions, fin rot or other issues.
But the Gulf, he noted, is much warmer and might be expected to have a higher incidence of disease than the colder north Atlantic.
“It’s like people and Ebola. That doesn’t start in the Arctic. I would imagine we would have a higher disease issue in the Gulf,” Murawski said. “There’s a significant fin rot issue here on the west side of Florida in red grouper. You wouldn’t think there was significant oil exposure there.”
Murawski said his team’s work consisted of deploying 5 miles of fishing line, festooned with thousands of hooks, along the seafloor at 90 sample locations between the Florida Keys and the middle of Louisiana. The group fished in depths ranging from 60 to 600 feet and captured 70 different species, yielding a broad picture of much of the Gulf’s food chain.
He said some species, in particular Southern hake caught around the DeSoto Canyon south of Pensacola, had a “much, much higher” incidence of disease. Hake live on the seafloor in water from 300 to more than 1,000 feet deep and prey on bottom dwelling creatures. During the Gulf spill, scientists documented a plume of tiny drops of oil drifting around in the depths of the DeSoto Canyon.
A few other areas were found to have a higher incidence of disease, particularly a “hot spot” found west of the mouth of the Mississippi River off the south coast of Louisiana. Murawksi called that find “unexpected” and said it deserved further attention.
Louisiana State University researcher Jim Cowan also singled out that area as having a lot of sick fish in an email exchange with the Press-Register last week.
“We found a higher percentage of red snapper in the northern Gulf had these things than down around the west Florida shelf,” Murawski said. “But we did find some off Florida with disease, too. Does that mean an animal was exposed to oil?”
He said his group had come up with a technique to analyze fish ear bones for oil exposure, looking at the percentages of vanadium and nickel present in the bones. But, he said, such a test cannot reveal whether oil exposure was linked to the BP spill.
“One thing we know is red snapper like to congregate around oil platforms and other oil-related structures,” Murawski said.
Murawski said his group will likely publish the first research paper associated with the federal study in a month or so.
