NOAA Fisheries continues to investigate an Unusual Mortality Event in which an unusually large number of whales and dolphins have been found from the Texas/Louisiana border through Franklin County, Fla., between 2010 and 2013.
Through Feb. 10, the mortality event involves 858 strandings along the Gulf Coast. Of those, only 5 percent were found alive, the National Oceanic and Atmospheric Administration states.
According to NOAA, 16 of the 33 stranded cetaceans (whales and dolphins) located this year through Feb. 10 were found along Louisiana’s shoreline.
In 2012, there were 91; 159 in 2011; and 138 from February through December 2010. All of these numbers were significantly higher than the 2002-09 yearly average of 20 strandings along Louisiana’s coast.
The increase in the number of strandings began two months prior to the April 2010 Deepwater Horizon explosion off Louisiana’s coast in the Gulf of Mexico.
In Mississippi, officials with the Institute for Marine Mammal Studies said in the past month 13 dead dolphins have been found. Eleven of them were babies, IMMS director Moby Solangi said.
“In 2011, we had seen a spike in baby dolphins that died,” he said. “Last year, things had stabilized and the numbers went down. Now we have another spike, and they’re all occurring at the same time.
“This is a spike that we don’t really understand. The ratio is unusual. We usually see a mix of males and females and different ages. These either were aborted or they died shortly after they were born.”
He said dolphins don’t normally begin giving birth until the end of February. The mothers swim closer to shore to give birth because the babies have to come up to the surface to take their first breath, Solangi said. Also, the shallow water is murky so sharks can’t see them.
Birthing season runs from late February until April or May. Solangi said if the deaths had occurred after the normal birthing season began, he wouldn’t be so concerned.
“Whether it’s a human reason or a biological reason, we need to know,” he said.
There are more dolphins off the coast of Mississippi, Louisiana and Alabama than any other place in the U.S. and that’s why people here see them so often, Solangi said.
Solangi said he got a report last week that three dolphins were found dead near Horn Island, but when IMMS crews got there, they found only two. He received photos of all three and the one not found had its head removed.
“A dolphin with no head is unusual,” he said. “Last year, we had people mutilating dolphins. We want people to know, because this is the birthing season, so they will see more animals closer to the shore.”
NOAA has identified brucella in 13 of the 58 dolphins tested. All but two of those tested dolphins were in Louisiana, according to NOAA’s website.
Brucella is a bacteria that infects many terrestrial and aquatic vertebrates around the world. The disease, called brucellosis, is best known for its role in causing abortion in domestic livestock and undulant fever in people.
Several negative health outcomes have been found in cetaceans with brucella infection including abortion, brain infection, pneumonia, skin infection and bone infection.
It is unknown how the disease spreads among whales and dolphins.
According to the Centers for Disease Control, people can get the disease when they are in contact with infected animals or animal products contaminated with the bacteria. Animals that are most commonly infected include sheep, cattle, goats, pigs and dogs, among others.
Additional reporting from The Associated Press.