Seattle ? Of the hundreds of sea turtles found dead along the Gulf Coast since the Deepwater Horizon oil-rig disaster, the majority examined so far appear to have died by drowning or aspirating sediment from the seafloor, a federal fisheries official said Thursday.

Early findings suggest that many of the endangered turtles may have died because they were getting caught in fishing nets, not the oil spill — at least in the immediate aftermath of the BP accident.

Investigators suspect that a last-minute shrimping season authorized after the April 20 blowout — and immediately before the first major wave of turtle deaths — could have led to the animals becoming trapped in trawlers’ nets.

But authorities have not ruled out the somewhat more remote possibility that a toxic algae bloom could have paralyzed the turtles and caused them to drown.

And Michael Ziccardi, a UC Davis veterinarian who leads the sea turtle and marine mammal oil spill response in the Gulf of Mexico, emphasized that necropsies have been conducted only on the first wave of turtles that washed up dead after the oil spill began.