Scientists say the number of dead dolphins washing shore is declining five years after the Deepwater Horizon Spill in the Gulf of Mexico.
According to the National Marine Fisheries Service, the number of dolphins and whales killed by exposure to the oil was 1,433. About 87 percent were bottlenose dolphins. Some washed ashore dead, other were stillborn or born prematurely.
"The number of mortalities in the region has declined since the peak years of 2010 to 2014," said Jenny Litz, a research biologist with the organization.
Scientists say some had a bacterial infection caused by the oil suppressing the dolphins' immune system. The marine mammals may have been exposed to the oil in various ways, including inhaling the vapors on the surface, absorbing it through their skin, ingesting it from the water or from the sediment while feeding, or from eating the oil-contaminated fish.
BP declined to comment on the dolphin die-off.
Scientists and other experts will next decide whether to officially declare that die-off stretch over, but no decision has been made yet. Researchers will also continue to investigate the long-term impacts oil exposure may have had on the survivors.
They're also trying to come up with plans for restoring the gulf, and the loss of the dolphins and whales that are so important to the food chain. Researchers estimate about 10,000 dolphins live in the gulf.
Litz told the Tampa Bay Times the 2010 Deepwater incident die-off will go down in history as "the largest, and longest, dolphin mortality event ever in the Gulf of Mexico."