BP Spill Slowing Down Speedy Mahi-Mahi Fish

A study by University of Miami scientists says mahi-mahi, one of the ocean's fastest fish, are slowing down due to the 2010 BP Deepwater Horizon spill, swimming nearly 50 percent slower than their unaffected counterparts.

The inch-long mahi-mahi are being used as part of a study to assess damage caused by the BP spill that spread oil across the Gulf of Mexico for 87 days in 2010. These fish were exposed when they were just infants, making them ideal subjects. Now, the oil is still impacting marine life, in this case the fish's swimming performance, Reuters reported.

Young mahi-mahi usually swim at a rate of five body lengths per second, and for a species that relies on its speed for survival, these findings could mean bad news.

"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 Martin Grosell, a professor at the University of Miami's (UM) Rosenstiel School of Marine and Atmospheric Science.

To assess the damage, researchers placed young mahi on a tiny fish treadmill to measure their speed. They treated the fish with oil from near the damaged wellhead and from the gulf's surface, and then transferred them to clean water for at least 25 days.

Though they once boasted quick speeds, the findings showed that their pace had since "dropped by about 37 percent," Grosell said.

In March, the Miami Herald reported, UM scientists working with the NOAA also confirmed that the BP spill amaged the hearts of tuna embryos, a condition that likely killed them in the wild.

Both studies - disputed by BP - concern researchers because mahi and tuna, whose numbers have dropped 75 percent in the last 40 years, started spawning just as the spill occurred.

And while it may seem more than plausible that the spill affected marine life after 4.9 million barrels of oil was dumped into the Gulf of Mexico, BP officials disagree with the findings.

"Even if there had been an effect on single-year class of such fish, the study does not provide evidence that an effect on that group of fish would have had population-level impact", said Jason Ryan, Spokesman from the BP.

These newest findings are published in the journal Environmental Science & Technology.