An Overview of Juvenile Salmon Ocean Ecology Studies in Alaska

Fisheries oceanographic surveys in the Bering Sea, Gulf of Alaska (GOA), and inside waters of Southeast Alaska provide valuable information on the early ocean ecology of juvenile salmon. These long-term monitoring studies provide time series data that are used to understand how patterns in the distribution, health, and condition of Pacific salmon affect survival. Surveys in the GOA have been used to identify stock-specific migration patterns of British Columbia sockeye salmon (Oncorhynchus nerka) and also track the distribution and occurrence of Chinook salmon (O. tshawytscha) stocks listed under the Endangered Species Act from coded-wire tag recoveries and genetic markers. Health and fitness is monitored through body condition, lipid storage level, and short term growth metrics such as Insulin-like growth factor which can aid pre-season forecasting efforts. Surveys in the Northern Bering Sea have provided information on size-selective mortality and juvenile abundance which has successfully predicted year-class return strength of Yukon River Chinook. An index of juvenile pink salmon (O. gorbuscha) abundance developed from surveys occurring in the inside waters of Southeast Alaska is combined with ecosystem metrics and used to generate pre-season forecasts of pink salmon harvest in Southeast Alaska.