Up to this point, the oil has contaminated a national forest, four wildlife refuges, three national parks, five state parks, four critical habitat areas and a state game sanctuary, which spreads along 1400 miles of the Alaskan shoreline. Recent scientific studies show that the oil continues to wreak havoc among many spawning salmon, herring, and other species of fish. This is even more devastating when considering that much of the wildlife around the sound is dependant on the high calorie, high fat content of the herring as their prime food source. Among the many casualties were 2800 sea otters, 300 harbour seals, 250 bald eagles, as many as 22 killer whales, and an estimated quarter-million seabirds. It is unclear how many billions of salmon and herring eggs and intertidal plants succumbed to the oil smothering. Within an ecosystem, each living thing depends on other living things. That means that when the fish died in Prince William Sound, there was less food or the seals that normally eat them. As those seals died, there was less food for the killer whales that eat seals (Knickerbocker 1999). This has led to a domino effect within the food chain, victimizing many of the animals surrounding the area, Intertidal mussel beds are still contaminated to this day. Twenty-three species of wildlife were affected by this oil spill, and only two species, the bald eagle and the river otter, have fully recovered. The species that are well on their way to a comeback include pink salmon, pacific herring, sea otters, mussels, black oyster catcher, common murre, marbled murrelet, and sockeye salmon. As with any environmental disasters, there are some animals that are showing little or no clear improvement since the spill occurred. This group includes harbour seals, killer whales, harlequin ducks, common loons, cormorants, and the pigeon gullomot. In some areas, that have been hardest hit by the oil spill, many of the species have an elevated level of morality.