Recovery of pink salmon spawning areas after the Exxon Valdez oil spill Exxon Valdez oil spill restoration project final report

To assess recovery of pink salmon (Oncorhynchus gorbuscha) spawning habitat in Prince William Sound after the Exxon Valdez oil spill, we analyzed sediment samples from William Sound after the Exxon Valdez oil spill, we analyzed sediment samples from stream deltas from 1989-1991 and 1995. In 1989, petroleum hydrocarbon concentration at 172 stream deltas (1-8 samples each) was bimodally distributed: 85 deltas had no detectable petroleum hydrocarbons (detection limit 2 pg/g); 87 deltas had 2-45,OOO pg/g. In 1995, petroleum hydrocarbons were still detected at eight of nine oiled streams we resampled, with mean concentration up to 242 pg/g. The polynuclear aromatic hydrocarbon (PAH) fraction was also analyzed to determine origin and toxic potential. The PAH in 1995 consisted mostly of the more toxic compounds with high molecular weight. Composition was consistent with weathered Exxon Valdez oil, and total PAH concentration ranged up to 1,300 ng/g. Interpolation between 1989 and 1995 indicated that PAH concentration exceeded 3,800 ng/g (minimum sediment concentration that reduces salmon embryo survival in the laboratory) at some stream deltas through 1993, but all streams were below this level by 1994. We conclude that tidal leaching of residual PAH into incubation substrate could explain persistent impaired embryo survival in pink salmon through 1993, and that spawning habitat had recovered by 1994. Michael L. Murphy, Ronald A. Heintz, Jeffrey W. Short, Marie L. Larsen, Stanley D. Rice. Title from cover. "August 1998." "Restoration project 97194." "Final report." Available also in electronic format on the Internet. Includes bibliographical references (pages 9-11). 1998 NMFS (National Marine Fisheries Service) Library Public Domain 1862