At a Glance
The number of dolphins stranded is three times what's normal.Scientists had predicted a dead zone in the Gulf due to an influx of freshwater from this year's heavy rains.They say the deaths could be a result of lingering effects of the BP oil spill.
At least 279 dolphins have been stranded along the U.S. Gulf Coast since Feb. 1, and about 98% of them have died, according to scientists from the National Oceanic and Atmospheric Administration.
The stranded dolphins represent about three times the usual number, the NOAA scientists said Friday.
Teri Rowles, coordinator for NOAA Fisheries’ Marine Mammal Health and Stranding Response Program, said scientists will investigate several possible causes of the deaths, including lingering effects from the 2010 BP oil spill and, more recently, freshwater flowing from high rivers and a Louisiana spillway in the wake of this spring's record rainfall across much of the central and southern U.S.
Scientists had previously predicted the freshwater influx could cause a massive dead zone in the Gulf.
Erin Fougères, administrator for the marine mammal stranding program in NOAA Fisheries’ southeast region, said 23% of the dolphins stranded from Louisiana to the Florida Panhandle had sores consistent with freshwater exposure. Such lesions are “not uncommon” in the spring, according to NOAA’s website.
Mississippi had 121 dolphin strandings as of Wednesday, with 89 in Louisiana, 32 in Alabama and 37 in Florida, Fougères said.
Moby Solangi, director of the Institute of Marine Mammal Studies in Gulfport, Mississippi, put that state’s total on Thursday at 126, and said the opening of the Bonnet Carré Spillway is at least partly to blame. The effects are worse for Mississippi’s dolphins than the BP spill, he said, noting that 91 dead dolphins were found in Mississippi during all of 2010.
BP spill effects included problems with lungs and adrenal glands, which produce stress-related hormones; blood abnormalities; and general poor condition, according to earlier reports. Those reports said the spill contributed to the Gulf of Mexico’s largest and longest dolphin die-off.
“We do know some of the health conditions ... are improving, but some have been slow to improve,” Rowles said. “Reproduction in the heaviest-oiled areas continues below normal.”
Dolphins continued to die for years because of oil spill damage, a 2015 study reported.
Freshwater exposure “doesn’t appear to be the cause of death for all animals, so that’s something we’re continuing to investigate,” Fougères said. Rowles noted that 70 percent of the carcasses were too decomposed for necropsy.