Spatial Patterns in Consumption Demand and Growth Potential of Juvenile Pink Salmon (Oncorhynchus gorbuscha) in the Gulf of Alaska

摘要

Salmon experience high mortality during early marine life, however, size-dependent mortality might be concentrated during specific life stages (Beamish and Mahnken 2001), and vary among regions (Mueter et al. 2002, 2005; Pyper et al. 2005). Survival of pink salmon during their marine residence appears to be determined in two stages, with the first stage characterized by high initial size-selective predation on juveniles as they enter the coastal regions (Parker 1965, 1968, Willette et al. 1999), and the second by significant size-selective mortality after the first summer growing season (Moss et al. 2005). Different stocks of fish will experience different conditions, as they inhabit different areas during different portions of their life cycle. However, each stock should respond to the same underlying mechanisms, and may express this two-stage mortality process differently. For pink and chum salmon, similar marine survival was reported for populations originating within regions (within 100-200 km) but differed among regions, suggesting that localized environmental processes operated similarly on early life stages in nearshore and coastal marine waters (Mueter et al. 2002, 2005; Pyper et al. 2005). Therefore, localized conditions affecting growth during the first summer in coastal shelf regions could determine the severity of over winter survival.