There were 62 dolphin deaths from Louisiana to the Florida Panhandle in March and an additional 39 in . . . → Read More: Dolphin die-off]]> http://www.usatoday.com/news/nation/environment/2010-06-06-dolphins_N.htm

There were 62 dolphin deaths from Louisiana to the Florida Panhandle in March and an additional 39 in April, said Erin Fougeres, a marine mammal biologist with the National Oceanic and Atmospheric Administration (NOAA) Marine Fisheries Service. The average is 18 for March and 13 for April, she said.

It’s the highest number of recorded dolphin deaths in seven years, said NOAA Public Affairs spokeswoman Monica Allen. For the entire Northern Gulf of Mexico, the combined range is 0-14 deaths a year, Allen said. NOAA has declared the deaths an “unusual mortality event” and ordered a panel of specialists to investigate them, she said.

The deaths are being investigated as scientists study the effect on marine life by the oil rig explosion, which has sent millions of gallons of crude into the Gulf. Since April 30, 29 dolphins have washed ashore dead within the designated spill area from Texas to Florida, Allen said. None of them showed external signs of “oiling” or damage from the oil slick, she said. From 5,000 to 6,000 strandings are reported in the USA each year, Allen said. If not dead, the dolphins are injured or unable to get back to the open water, she said.

Moby Solangi, president of the private, non-profit Institute for Marine Mammal Studies in Gulfport, Miss., attributed this recent death spike to a colder than usual winter. Though the deaths in March and April are unusually high, he said, there is some variation in death rates from year to year. “Mortality is not constant,” he said.

NOAA also is monitoring a small spike in dolphin deaths in South Carolina, Fougeres said, as well as deaths on Florida’s Atlantic Coast. Marine biologists at Hubbs-Sea World reported 40 deaths in Florida’s Indian River Lagoon between Volusia and Brevard counties since Jan. 1. The annual norm is 65.

Seven criteria are needed for an unusual mortality event to be declared, said Megan Stolen, a biologist with Hubbs-Sea World. They include a marked increase in mortality, localization of the deaths, similar or unusual diseases or pathologies and deaths accompanied by odd behavior.

The Indian River Lagoon had an unusual mortality event in 2008, when 89 bottlenose dolphins died in Brevard and Volusia. No cause was ever found. Although the latest lagoon deaths meet the increase in mortality criteria, they meet none of the others, Stolen said. The deaths were spread out over a large area and have no common pathological links, she said. “Right now, we’re higher than normal, and everyone is concerned, but it’s not fitting a pattern that suggests there is one cause,” she said.

Schweers reports for Florida Today in Melbourne