As scientists study the effects of the Valdez oil spill, they are discovering new problems. The oil not caused the immediate deaths of many animals. It also had longer term effects on many other animals.The harbor seal ( a marine mammal ) is one example. At first,scientists hoped that the seals would stay away from the areas where there was oil.But instead, the seals swam right though the oil and came out oily beaches. Scientists noted that these seals seemed sick, and in fact many disappeared. At an earlier counting in 1975, there were about 13,000 harbor seals in Prince William Sound. After the spill, there were only about 2,500. Research on the bodies of dead seals showed that they suffered some brain damage. This may have caused the seals to become confused and drown. The oil also seems to have affected the ability of female seals to have healthy babies. In the year after the oil spill, there were many more deaths than usual among baby seals.