|Veterinary technician Wendy Hatchett lifts a dead bottlenose dolphin that was found|
on Ono Island, Ala., and brought for examination to the Institute for Marine Mammal
Studies in Gulfport, Miss., on Feb. 22.
Hundreds of bottlenose dolphins have washed up dead in the Gulf in the past year, an unexplained rise in deaths that has scientists concerned. Oil on six of the dolphins has been directly linked to BP's blown-out well, but researchers say it's too soon to conclude whether or not the oil was responsible or if their demise was caused by something entirely unrelated, the National Oceanic and Atmospheric Administration said.
"Some of these stranded dolphins have come in with some type of suspected oil, ... but it doesn't mean that it's an acute cause of death," NOAA spokeswoman Karrie Carnes told AOL News today by phone.
According to NOAA data, 293 dolphins have washed up dead in the Gulf of Mexico since the April 20 spill, a major increase compared with an average of 74 dolphins per year in the previous decade. But researchers note that the spike in deaths actually began in February 2010, two months before the BP explosion. Most of the dead dolphins are babies or even preterm.
"The northern Gulf of Mexico is no stranger to dolphin mortality deaths," said Blair Mase, a regional marine mammal stranding coordinator for NOAA, referring to deaths researchers consider unexplained. "Since 1990 we've had 11 dolphin mortality events in the Gulf, so it does occur with regularity. What's so unusual about this case is that we've seen a sustained increase in dolphin mortalities since February 2010. So we're particularly concerned."
Researchers say finding out what's causing the increase in deaths will take months, and ultimately more than one factor may be to blame. The marine mammals could have been killed by naturally occurring algae blooms, for example, or an infectious disease.
Still, if scientists find conclusive evidence that oil from last year's Deepwater Horizon spill played a role in the mammals' deaths, it could mean more penalties for oil giant BP.
BP did not immediately respond to a request for comment today from AOL News.
An unusually high number of sea turtles have washed up dead in the Gulf of Mexico as well. While the deaths are so far unexplained, no oil was found on their bodies, and scientists believe they may have been accidentally drowned in fishing gear, suffocated by algae blooms, or killed by speedboats or other watercraft. Twenty-five of them are the endangered Kemp's ridley turtle.
Officials say they are still investigating.