Los Angeles Times
By Lianne Hart
March 19, 2007
An unusually high number are washing up along Texas' Gulf Coast this calving season for unknown reasons.
GALVESTON, TEXAS — An unusually large number of dead bottlenose dolphins have washed ashore near this Gulf of Mexico city in the last month, and investigators are looking at laboratory slides, satellite photos and anything else they can think of in their search for clues.
About 180 dolphins are stranded in Texas each year, many from January through March — their calving season, when infants may die during birth or become separated from their mothers and are unable to survive alone.
The 47 bodies found recently included many newborns with umbilical cords still attached. That is three times the number found during the same period last year.
"Right now we don't know what's going on, but it is definitely significant," said Daniel Cowan, a pathologist at the University of Texas Medical Branch in Galveston. "Nowhere else in Texas is having this kind of problem. They're coming in in multiples."
Investigators theorize that poisonous substances seeping into the water off Louisiana may have killed the dolphins, which were then carried by currents to the Texas shore.
They are also scanning satellite images for toxic algae blooms and considering the possibility of morbillivirus, a dolphin virus similar to one that causes canine distemper.
Cold winter waters can also kill dolphins, said Cowan, who is also the director of the Texas Marine Mammal Stranding Network, a largely volunteer rescue group operating along the Texas coast. Most of the strandings occur south of Galveston.
Blood, tissue and other samples from the dolphins will be sent to the National Marine Fisheries Service in Florida for toxicology tests, Cowan said.
In Galveston, scientists are conducting necropsies — the animal equivalent of an autopsy — and looking for signs of bacterial infection, wounds, disease or parasites. Results probably won't be known for at least several weeks.
The dolphin carcasses have been found from Galveston to Sabine Pass, about 70 miles to the northeast. Necropsies are conducted on the beach because most of the dolphins have been too decomposed for laboratory testing.
The dolphins are then buried deep in the sand, said Heidi Watts, operations coordinator for the Texas Marine Mammal Stranding Network.
Last week the investigation spread to Louisiana, where the Coast Guard began aerial searches for dolphin bodies and clues to what may be killing them.
"We're checking out everything possible," Watts said. "We don't know what's happening."