OUR FISH: Deepwater Horizon oil fouled the Gulf of Mexico 10 years ago and still affects fisheries

– APRIL 18, 2020

(From nwfdailynews / by Ed Killer, Treasure Coast Newspapers / April 18, 2020)

It exploded with a fatal fury on the night of April 20, 2010. The inferno shot flames hundreds of feet into the sky from a platform more than 100 feet above the surface of the Gulf of Mexico. The resulting fireball of the explosion was witnessed more than 40 miles away.

Eleven oil platform workers died that night during the Deepwater Horizon disaster. Another 17 were injured. It was a sheer miracle the remainder of the crew of 126 on board that night escaped with their lives.

The fire could not be extinguished. About 36 hours after the tragedy began, the huge drilling platform sunk beneath the waves. It sits on the sea floor in 5,000 feet of water about 41 miles off the coast of Louisiana.

Streaming Oil

What we all vividly remember is the underwater video of oil streaming freely from a well head nearly a mile beneath the surface of the Gulf. It seemingly went on forever. It was finally capped 87 days later on July 15, putting a temporary end to the human tragedy and environmental nightmare.

During that time, an estimated 210 million gallons of oil poured upwards into the waters of the Gulf. Another 1.84 million gallons of dispersant chemicals were flown and sprayed onto the oil spill to help break it up. Over 16,000 miles of tidal coastline was spoiled. Environmentalists were challenged with wondering which poison was worse — the oil or the cure?

Fish oil

At the time, scientists and fishermen knew the long range effects on marine life would be felt for years to come. Ten years later, some of those effects are now being quantified and understood more clearly.

The quick message from the scientific community? Some fish species suffered problems right away, some suffered later on and others are still being discovered to have lingering problems.

A team from the independent Gulf of Mexico Research Initiative’s Center for Integrated Modeling and Analysis of Gulf Ecosystems (C-IMAGE), an international consortium of professors, post-doctoral scholars and students from 19 collaborating institutions in 15 countries, helped to conduct the research. According to the University of South Florida, nearly 10 years of scientific findings were published Wednesday in the journal Nature Scientific Reports.

The team studied more than 2,500 individual fish of 91 different species from 359 sampling locations throughout the Gulf of Mexico. Those sampling locations included spots from Florida to Texas to Mexico to Cuba.

Sorry, Charlie

Oil from the spill was found in every one of the fish samples collected. Most had levels safe for consumption, but the finding indicates how widespread the impact was.

The three species the report identified as suffering the most problems:

– Yellowfin tuna

– Golden tilefish

– Red drum (redfish)

All three are economically important species. Yellowfin tuna and golden tilefish are staples in the food supply targeted and sold by commercial fishermen working the northern Gulf of Mexico from states such as Florida, Alabama, Mississippi, Louisiana and Texas.

Red drum, better known in some places as redfish, are typically targeted and caught in inshore coastal waters by recreational anglers. All Gulf states allow harvest by recreational anglers.

Scientists examined the bile in fish that were sampled. Bile is produced by the liver as part of the digestion process, and stores waste inside the body of the fish. Researchers checked for levels of polycyclic aromatic hydrocarbons (called PAHs), which happen to be the most toxic chemical component of crude oil

Low oil

Economically important species which showed low levels of PAHs surprised the researchers, too. Among them were bottom dwelling species such as:

– Red snapper

– Yellowtail snapper

– Vermilion snapper

– Red grouper

– Sharks and barracuda

“We were quite surprised that among the most contaminated species was the fast-swimming yellowfin tuna as they are not found at the bottom of the ocean where most oil pollution in the Gulf of Mexico occurs,” lead author Erin Pulster, a researcher in USF’s College of Marine Science, said in a press release.

Pulster was puzzled that a fish like yellowfin tuna, known to swim in the upper part of the water column and cover great distances, would have a high level of PAH. Less surprising was that a tilefish would indicate high PAH. It lives in burrows it digs in the mud in the bottom of sea and has a slow metabolism.

The study indicated there is still a lot of oil trapped in the sediments at the floor of the Gulf. It gets re-suspended every time there is a hurricane or a strong current, and is right back in the food web for these fish.

A different study published by USF measured high concentrations of PAHs in the liver tissue and bile of 10 popular grouper species. Yellowedge grouper had a PAH concentration which increased more than 800 percent from 2011 to 2017.

Missed baseline

The report noted virtually no studies of this sort were conducted prior to the 2010 event. The studies were made possible as part of the $500 million commitment from British Petroleum, which was ultimately assigned the majority of the spill’s responsibility by the U.S. Government. The funding, which ends this year, was administered by Gulf of Mexico Research Initiative.

What also is not included in any research project is how an oil spill in the Gulf of Mexico can impact fisheries in the Atlantic nearby. The Loop Current moves water from the Gulf around Key West and up the Florida Straits into the Gulf Stream.

Connecting currents

When the spill took place, east coast charter fishermen were worried. In the aftermath years, migratory runs of fish like king mackerel, dolphin, tuna and even some billfish were believed to have been effected, however with no scientific evidence. Many species, including great white sharks we have recently learned, travel between the two bodies of water when it is time to spawn or give birth.

In these uncertain times, 10 years in the past feels like a lifetime ago. Oil spills are rare, but when they occur in open waters, we need to remember the ocean connects us all whether we realize it or not.

Read the full article here

GoMRI “In the news” is a reposting of articles about GoMRI-funded research (published by various news outlets).