Assessing Prey and Competitor/Predators of Pink Salmon Fry. 'Exxon Valdez' Oil Spill Restoration Project Final Report

摘要

Multi-frequency acoustic/net sampling assessments of the pink salmon food supply and predators were conducted in Prince William Sound during spring 2001. Five cruises were completed between April 18 and June 15,200 1. The results of this monitoring were in sharp contrast with observations from the previous year. Overall the abundance of large copepods (primarily Neocalanus) was much lower in 2001. The abundance was highest at the beginning of the monitoring in mid-April, but progressively declined rather than increased as was seen in 2000. Highest biomasses were observed above the deep hole adjacent to Naked Island, and the lowest biomass within protected bays, including the locations of Esther and Main Bay hatcheries. The pattern of fish abundance and distribution was generally similar both years. Highest fish abundance was in the main basin and relatively deep. Abundance in the pink salmon out-migration corridor increased slightly over the spring, but was low overall. However, fish in the out-migration corridor showed strong near-shore orientation in 2001, a pattern not seen in 2000. The results of this monitoring should provide valuable insights into the complex environmental conditions that govern juvenile salmon survival.