A government-funded survey of the entire Gulf of Mexico last summer found more sick fish in the area of the 2010 oil spill than anywhere else, according to the top University of South Florida scientist in charge of the project.
"The area that has the highest frequency of fish diseases is the area where the oil spill was," said Steve Murawski, an oceanographer who previously served as the chief fisheries scientist of the National Oceanographic and Atmospheric Administration.
That doesn't necessarily mean the red snapper and other fish with nasty skin lesions were victims of the Deepwater Horizon disaster, he said. That same area has lots of oil rigs, leaky pipelines and even natural oil vents in the sea floor that could be the source of any contamination that has affected the fish.
"Even if the disease is from oil," he said, "it's another step to show it's from the oil spill."
But the USF findings, announced at a scientific conference this month, have been hailed as a big step forward by researchers from other institutions pursuing similar studies.
"We still are seeing sick fish offshore and the USF survey confirmed our findings of 2 to 5 percent of red snapper being affected," James Cowan, an oceanography professor at Louisiana State University, said in an email to the Tampa Bay Times.
In addition, Cowan said, laboratory studies of those sick fish "are beginning to trickle out that show that chronic exposure to oil and dispersant causes everything from impacts to the genome to compromised immune systems. Similar findings … are being found in shrimps and crabs in the same locations."
While Murawski is cautious about saying there's a connection, Cowan, who has been studying fish in the gulf for 25 years, said, "I absolutely believe these things are connected to the spill."
There are signs the lesions may be spreading. According to Will Patterson of the University of South Alabama, "they're now showing up in fish being caught in the surf here in Alabama." Patterson said he plans to do some scientific sampling of the surf fish this coming week.
The USF scientists plan a second survey of the gulf next month, and also plan to check whether the sick fish they have caught suffer from immune system and fertility problems. Their goal, according to Ernst Peebles, another USF scientist working on the study, is to be able to report something definite by April 20, the second anniversary of the 2010 Deepwater Horizon explosion.
One problem with the USF study, though, is that nobody made a similar gulf-wide survey of fish health prior to the disaster, Peebles and Murawski said. Without a baseline study, it's hard to say what's normal.
They have found more sick fish than what they would expect based on previous studies, Peebles said, but the earlier studies took place in colder waters.
However, what started the investigation were reports from longtime commercial fishermen that they were pulling in fish with skin problems like they'd never seen before.
The Deepwater Horizon rig explosion killed 11 workers. Two days later oil began spewing from a pipe a mile beneath the surface, and BP and its partners were not able to stop it until July.
Before BP could cap the well, 5 million barrels of oil gushed into the gulf. The company sprayed 1.8 million gallons of chemical dispersant to prevent it from reaching shore, but 2.5 million pounds of it washed up on Florida's beaches and in its marshes. Cleanup crews are still picking up tar balls from the beaches of Alabama and Mississippi.
In late 2010 and early 2011, fishermen working the area the spill had covered reported finding red snapper and sheepshead with lesions, fin rot and parasite infections. On some of them, the lesions had eaten a hole straight through to the muscle tissue.
A few fishermen brought their suspect catch to scientists. When the scientists cut them open, they found the fish also had enlarged livers, gallbladders, and bile ducts — indications their immune systems may have been compromised by oil.
So last summer, with funding from NOAA and cooperation from the state's marine science laboratory in St. Petersburg, the USF scientists chartered fishing boats from Madeira Beach and Panama City and set out to cover the entire gulf. They dropped their lines about 600 feet deep — the spill began at 5,400 feet — and caught about 4,000 fish.
Southern Offshore Fisheries Association president Bob Spaeth helped set up the voyage, and wasn't surprised by its results.
His big worry is not that a percentage of the fish got sick, he said, but that the size of the fish population may have been reduced. That could lead federal regulators to reduce how many fish they're allowed to catch. "If you reduce our quota," he said, "we'll be out of business."
In the meantime, there have been other signs something unusual might be going on in the northern part of the gulf. More than 600 dolphins have stranded along the gulf beaches over the past two years, which in some areas is 10 times more than normal, according to NOAA scientist Erin Fougeres. So far 10 have tested positive for a bacterial infection called Brucella, which the scientists believe may be a sign that the oil spill harmed the dolphins' immune system.
The USF survey included some disquieting results for Florida anglers who think they don't have to worry about the northern gulf where the spill occurred. Peebles' lab examined the ear bones of the fish caught in the gulf, because those bones contain clues to the fish's life.
"I see fish caught off this coast," Peebles said, "who spent the early part of their lives up there."
Craig Pittman can be reached at firstname.lastname@example.org.