According to the Associated Press, the effects of the BP oil spill on the Gulf of Mexico and the animals that live in it will take place over years, if not decades, a new report by a prominent environmental group says. The National Wildlife Federation said it is much too soon to make snap judgments about how much harm has been done. The report, which did not break any new scientific ground, was issued in advance of the first anniversary of the BP PLC spill on April 20. For dolphins, the report highlighted a spate of strandings since January. Federal researchers are looking into the deaths, which are more than four times the normal amount, according to the National Oceanic and Atmospheric Administration. The report said the spill could add more stress to the depleted Atlantic Bluefin tuna stocks that spawn in the Gulf. Bluefin tuna stocks have decreased by about 80 percent since 1970. The report said shrimp could also be hurt by the ongoing erosion of Louisiana''s coastal wetlands and the oiling that the Louisiana coast took during the spill. The report said it would be important to watch for how much shrimp is harvested every year and whether oil contamination lingers in the delta''s wetlands.