An assessment of oil spill impacts on pink salmon populations in Prince William Sound following the Exxon Valdez spill

Pink salmon, Oncorhynchus -gorbuscha is the main salmon species of commercial importance in Prince William Sound. They have a two-year life cycle and have adapted to spawn in the intertidal reaches throughout the impact area of the Exxon Valdez oil spill, thus representing the species of highest potential risk for spill-related injury. The post-spill field and laboratory studies of pink salmon early life stages included examination of potential effects on 1989, 1990, and 1991 eggs, fry and juveniles. Generally high survival, ranging from 77% to 100%, was observed in both oiled and reference streams. In 1990, egg viability was 90.6% from reference streams and 91.1% from oiled streams as determined through incubation studies. Adult pink salmon in the post-spill years of 1990 and 1991, progeny of the year classes considered most vulnerable to the oil spill, returned in high numbers, with the wildstock spawners exceeding their parent year returns. The early lifestage data, in combination with observations of the strength of post-spill returns and analyses of escapement, are the bases for the conclusion that there is not a meaningful effect of the oil spill on wildstock pink salmon at the population level in Prince William Sound