GULF OF MEXICO - Environmental Writer Federal officials say 189 dead sea turtles, birds and other animals have been found along Gulf of Mexico coastlines since a massive oil spill started last month.

The total includes 154 sea turtles, primarily the endangered Kemp's ridley variety, plus 12 dolphins and 23 migratory birds.

But in a phone news conference Tuesday, officials said they don't know how many were killed by oil or chemical dispersants. Barbara Schroeder of the National Oceanic and Atmospheric Administration's fisheries program says necropsies have not detected oil in the bodies of the sea turtles.

Acting U.S. Fish and Wildlife Service Director Rowan Gould says the spill's effects could be felt for decades and may never be fully known because so many affected creatures live far offshore.