1997 Survey of Juvenile Salmon in the Marine Waters of Southeastern Alaska
Twenty stations were sampled monthly along a primary marine migration corridor in the northern region of southeastern Alaska to assess the distribution, growth, mortality, and diet of wild and hatchery stocks of juvenile Pacific salmon.
Increasing evidence for relationships between Pacific salmon (Oncorhynchus spp.) production and shifts in climate conditions has renewed interest in processes governing yearclass strength in salmon (Beamish 1995). However, actual links tying salmon production to climate variability are understood poorly due to a lack of adequate time-series data (Pearcy 1997). In addition, mixed stocks with different life history characteristics confound attempts to accurately assess growth, survival, distribution, and migratory rates of specific stocks. Synoptic time series of ocean conditions and stock-specific life history characteristics of salmon are needed to adequately identify mechanisms linking salmon production to climate change. Until recently, stock-specific information relied on labor-intensive methods such as coded-wire tagging (CWT; Jefferts 1963). However, advances in mass-marking methods using otolith thermal marks (Hagen and Munk 1996) now offer an opportunity to examine growth, survival, distribution, and migratory rates of specific stocks.
Approximately 123 million thermally-marked juvenile chum salmon (0. keta) were released in the spring of 1997 from two major enhancement facilities in the northern region of southeastern Alaska. Samples of these fish were collected along a seaward migration corridor to determine whether competitive interactions between hatchery and wild stocks exist and to obtain stock-specific life history characteristics such as growth, migration, diet, condition, and size-selective mortality. Oceanographic data were also collected to expand existing time senes.