Mahi-Mahi May Have Lost Swimming Speed after BP Oil Spill

In the fourth year since the 2010 BP Deepwater Horizon oil spill, researchers are still discovering its effects on nearby fish and hunting for last traces of oil.

Mahi-mahi that were exposed to the oil while they were young are slower swimmers compared with unaffected fish, according to a new University of Miami study.

Researchers tested the swimming speed of fish exposed to oil traces to find that it "dropped by about 37 percent," said Martin Grosell, a professor at the University of Miami's Rosenstiel School of Marine and Atmospheric Science, as quoted by The Telegraph.

The 2010 spill took place over 87 days, flooding the Gulf of Mexico with around 4.9 million barrels of oil.

Scientists can't define damage on the mahi-mahi population with certainty due to limited statistics on the fish, but the study found that embryos and young fish appeared to be substantially slower swimmers after being affected by the oil. This handicap could be devastating for the mahi-mahi, which is a popular fish for anglers and restaurants. The fish is said to be among the fastest swimmers on Earth, moving at a rate of about five body lengths per second. 

"The worry is that if you have reduced swimming performance you're going to be less effective at capturing prey, and less effective in avoiding [predators]," said Grosnell, as quoted by The Telegraph.

Mahi-mahi embryos and young fish were exposed to oil taken from the area of the spill, after which they spent 25 days living in clean water. The research team tested their swimming speeds with an aquatic treadmill.

In response, BP denied that the spill could have had long-term effects on mahi-mahi in the Gulf.

"The study does not provide any evidence to show that an effect on that group of fish would have had a population-level impact," said BP spokesman Ryan Jason, as quoted by The Telegraph.

Today marks the fourth anniversary of the oil spill, and a specialized team explored the Gulf last week to find any last traces from the disaster, the Pensacola News-Journal reported.