Study: BP Oil Slowed Fast Fish

Big Oozy oil slowed down one of the fastest fish in the Gulf, a new study shows. According to University of Miami researchers, oil from the Deepwater Horizon disaster cut the ability of mahi mahi to swim by up to 37 percent. Along with impairing one of mahi mahi's key survival skills, a new study published in the journal of Environmental Science and Technology shows oil could have slowed other species of fish, as well.


A staple on many seafood restaurant menus, mahi mahi are also highly sought by sport fishers for their dazzling array of incandescent colors and size. Also known as the dolphinfish, they can be elusive due to their speed.


Their eggs float on the surface of the Gulf and other bodies of water, likely leaving many embryos exposed to oil during the 2010 disaster.


Using crude oil collected from the surface of the Gulf during the 2010 disaster, the researchers measured swim speeds for two groups of mahi mahi that appeared to be outwardly healthy. Larval mahi expsed to oil for 48 hours showed a 37 percent decrease in swim speeds. A second group exposed to oil for 24 hours had decreased speeds of 22 percent.


Hardly just about declining splits, the researchers say the decrease in swim speeds cuts into one of the fish's critical survival skills.


“If you harm a fish’s ability to swim you also harm its ability to perform actions that are critical for survival, such as catching prey and evading predation," wrote Edward Mager, UM Rosenstiel School postdoctoral associate and lead author of the study. Mager added that the decreased swim speeds were likely to appear in other large fish.


The latest findings follow a March study that showed heart defects in tuna and amberjack embryos as a result of exposure to BP oil. 


BP didn't agree with the findings, issuing the following statement:


The oil concentrations used in the University of Miami study were rarely seen in the Gulf during or after the Deepwater Horizon accident.  The oil material used in the test had a higher percentage of compounds of concern than the water samples actually collected in the field, and such tests do not tell us how mahi-mahi in nature were actually affected by the spill, or if they were even affected at all.  Further, the study provides no evidence that oil would have affected the adult fish.  The tests only looked at impacts to fish under one year of age.  Even if there had been an effect on a single-year class of such fish, the study does not provide any evidence to show that an effect on that group of fish would have had a population-level impact.

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