Evidence That Sea Turtles are Drowning in Shrimp Nets

Associated Press archive. Institute of Marine Mammal Sciences researcher Justin Main takes photographs of a dead sea turtle on the beach in Pass Christian, Miss., in May. Photo courtesy: Nola.com

More than half the endangered sea turtles dissected after being found dead in Mississippi in the wake of the Gulf oil spill -- 21 of 40 -- had sediment in their lungs, indicating they probably drowned in trawl nets near the sea floor, a federal biologist said Thursday.

The bodies are still being tested for toxins, especially those from algae blooms, but that's unlikely as a cause of death, said Brian Stacey of the National Oceanographic and Atmospheric Administration.

The numbers make other causes of drowning unlikely, Stacey said.

"We do get sporadic entrapment in wrecks, or entanglements in nets," but not nearly that many, he said.

Authorities have said they were investigating whether turtles might have drowned in shrimp nets.

All five species of sea turtles in the Gulf of Mexico are threatened or endangered; federal law requires escape hatches called turtle excluder devices on shrimp nets, which are towed along the bottom where shrimp congregate.

Most of the 411 dead and 128 live turtles found since April 30, when collections began, have been Kemp's Ridley sea turtles, the smallest and most endangered.

According to figures compiled by the U.S. Fish and Wildlife Service, 210 dead turtles were found in Mississippi, 88 in Louisiana, 66 in Alabama, 43 in Florida and four in the Gulf of Mexico. Only five turtles found dead on the shore had oil on them.

Collections started a day after Louisiana opened an emergency season to let shrimpers harvest a crop ahead of the oil spill.

On Monday, Mississippi authorities ordered shrimpers trawling in the Mississippi Sound to pull up their nets every 30 minutes rather than every 55 minutes, to reduce the chance of drowning turtles.

Turtle strandings are common along the Gulf of Mexico, but this year's numbers are higher than usual, Stacey said.

He spoke by phone from Gainesville, Fla., where he was about to resume necropsies -- animal autopsies -- on sea turtles.

He said the 67 necropsied so far included 26 too decomposed for detailed study.

More than 120 live sea turtles, 84 of them found covered in oil, are in rehabilitation centers. They include 76 found swimming in oil out in the Gulf of Mexico, two caught in oil skimming operations, and two each found in Alabama, Florida and Louisiana waters.

Another 42 rescued turtles did not have any visible oil on them, and two have not been classified. At least four were released.

The BP-operated rig Deepwater Horizon exploded April 20 and sank two days later, generating the massive oil spill.