Matt Sedensky / Associated Press

WEST PALM BEACH, Fla. (AP) -- More sea turtles were killed orinjured in the Gulf of Mexico in the months following the BP oilspill than in any similar period during the past two decades, areport released Wednesday found.

While the report suggested many of the 600 turtles were hurt bythe spill, it's still not clear exactly how many died fromingesting the crude or how many drowned in fishing nets in thescramble to catch shrimp and fish before the oil ruined them. Thesea turtles could have also been killed by cold weather or otherfactors unrelated to the spill.

The report said the rate of dead, disabled and diseased seaturtles discovered in the months following the massive April 20spill was four to six times above average. The analysis -- by theNational Wildlife Federation, the Sea Turtle Conservancy and theFlorida Wildlife Federation -- was conservative and only took intoaccount turtles found on shore, not those rescued or recovered atsea.

Researchers with the federal government said it would take yearsto determine the full impact of the spill on sea turtles.

Necropsies have been done on more than half of 600 turtlecarcasses, and while some may have died from oil, most of theturtles drowned in fishing gear, said Monica Allen, a NationalOceanic and Atmospheric Association spokeswoman.

Unseasonably cold temperatures last winter were also detrimentalto sea turtles, most of which are considered endangered, said GaryAppelson, policy coordinator for the Sea Turtle Conservancy.

'Sea turtles have had a tough year,' Appelson said.

Doug Inkley, senior scientist at the National WildlifeFederation and a co-author of the report, said while some of theturtles' deaths could not be linked to the spill, the muchhigher-than-usual number indicated the disaster was at leastpartially responsible.

He said turtles suffered more than other species because theirpopulations are already low and face long odds of reachingadulthood. It takes turtles 10 to 30 years to reach maturity,meaning it could take decades to restore the damage to theirpopulation, Inkley said.

'Of all the species affected by the oil spill, those for whichI have the greatest concern are the sea turtles,' he said.

Wildlife officials undertook Herculean efforts to try to saveturtles during the oil spill. All told, hundreds of loggerheadnests containing nearly 15,000 hatchlings were successfullytransported and later released along the Atlantic.

Besides urging lawmakers to uphold funding for beachconservation, the report's authors urged the elimination ofsubsidies for construction projects along coastlines and theprotection of less developed areas of the shore.

More than 90 percent of North American sea turtle nestinghappens on Florida's beaches. Five of the planet's seven species ofsea turtles are found in the state. Four of those -- green,hawksbill, leatherback and Kemp's ridley -- are consideredendangered, or at risk of becoming extinct.

The fourth, loggerheads, is listed as threatened, or likely tobecome endangered.

(Copyright 2011 by The Associated Press. All Rights Reserved.)