Fishermen are on the water every day, which means they are often the first to notice when something changes. After the BP Deepwater Horizon oil disaster, we heard reports from fishermen that they were catching more fish with lesions than they had ever seen before. Immediately after hearing these reports, Dr. Jim Cowan at LSU began investigating the frequency, location and cause of the reported lesions. Many other scientists have collected data on this same issue, and last week a group from the University of South Florida published the first round of results in a scientific journal.

Through extensive study, the scientists ruled out other potential causes, such as pathogens or oceanographic conditions, and concluded that the BP oil disaster is the likely cause of the fish lesions. Oil has a distinct chemical signature that allows scientists to differentiate between different origins, and contamination in the sick fish was a better match to oil from BP’s Macondo well than any other source.

For the Gulf, studies that help us understand the lingering impacts of the BP oil disaster are critical to achieving recovery. They are also a reminder that we cannot close the door on studying the effects of the disaster or the impact of our restoration efforts until we are certain the job is complete. The results of the USF study are only the beginning of this story about how fish were impacted by the BP oil disaster. In order to achieve complete recovery, we need long-term research on how lesions and other oil impacts affect the survival and reproduction of fish, how their populations are responding to habitat and water quality restoration efforts, and what that means for the fishermen who first identified the problem.

Location of sampling stations and the percent of skin lesions per station for June–August 2011. The percent of skin lesions at a station is indicated as follows: white circles = 0%, red graduated circles = 0.1–2.0%, 2.1–4.0%, 4.1–6.0%, and >6.0% (from smallest to largest). The gray shading is the cumulative distribution of surface oil occurring during the duration of the Deepwater Horizon (DWH) event. Map credit: Murawski et al., 2014