GALVESTON — Nearly 30 dead dolphins have been found along Texas shorelines since an accident spilled oil March 22 near the Texas City Dike.
Cleanup officials said it was unclear whether any of the deaths could be attributed to the spill, or whether the number of reported dolphin deaths was a result of having more people than usual on the lookout for wildlife.
Keeley Belva, a spokeswoman for the Oceanic and Atmospheric Administration, said in an email Thursday that 29 dead dolphins had been recovered within the response area set up for the oil spill. Four of the recovered dolphins showed signs of external oiling, Belva said, another two were still being evaluated to determine if they had been oiled.
Necropsies are being performed by biologists from NOAA and the Texas Marine Mammal Stranding Network.
“We are unable to tell at this time whether the dead animals with evidence of external oiling were externally covered in oil post mortem or were oiled before death,” Belva said.
Belva said stranding rates for bottlenose dolphins in Texas are generally high at this time of year. Historically, an average of 33 dolphins strand in Texas each March.
Finding a dead dolphin on its own on the Texas seashore is not necessarily unusual, said Dr. Bernd Wursig, a marine biologist and expert on marine mammals at Texas A&M University at Galveston.
“In these kind of configurations of bays, estuaries, not all dolphins that die come to shore, but it happens much more often than in places with just open shoreline, such as California,” he said.
There are occasions, known in environmental circles as Unusual Mortality Events, where certain species of marine life begin dying off in large numbers. Such an event occurred in Texas in 2011, when more than 120 bottlenose dolphins were found dead in five counties in five months.
It was unclear Thursday whether environmental officials considered the number of dead dolphins found recently as unusual.
Wursig urged caution in attributing the deaths to the oil spill before more conclusive results are available.
In the days immediately after the spill, dolphins appeared to have abandoned the area, Wursig said in a blog post on TAMUG’s website. After about four days they returned and could be seen socializing and feeding in the area.
Wursig and other biologists said they will be keeping an eye on the marine mammal population for years to come as scientists monitor the effects of the spill on the bay’s ecosystem, particularly after a study released last month concluded bottlenose dolphins in Louisiana that were exposed to the Deepwater Horizon oil spill were suffering from a range of maladies, including lung disease and adrenal problems.
Contact reporter John Wayne Ferguson at 409-683-5226 or firstname.lastname@example.org