Highlights in 2017-2018: •
• Fishes employ a diverse range of strategies for reproduction, growth, and survival to adapt to the complexity of the Gulf of Alaska ecosystem. For example, fishes use temporal niches for reproduction that result from strong seasonality in this ecosystem. • The Gulf of Alaska IERP contributed to identifying indices for the Ecosystem Considerations chapter of the North Pacific Fishery Management Council Stock Assessment and Fishery Evaluation report. The results influenced the development of separate indices to hindcast conditions for eastern and western regions of the Gulf of Alaska ecosystem. • Results of the Gulf of Alaska IERP are being incorporated into single-species stock assessments via a new ecosystem and socio-economic profile (ESP) framework. Through this process, a set of metrics are graded to determine vulnerabilities throughout the life history of a fish stock and relevant ecosystem and socio-economic indicators are identified for continued monitoring. • Genetic analyses of salmon captured in southeast Alaska in July 2011-2015 found that juvenile salmon in the Gulf of Alaska in mid-summer are predom- inantly from the Columbia River, comprising nearly 80% of the samples. Sampling in the Gulf of Alaska may allow assessment of the marine survival of juvenile Columbia River Chinook salmon two years prior to their return to the river as adults.
The eastern and western Gulf of Alaska regions display differences in physics and biology that affect the survival and recruitment of fishes, with a transi- tion zone between 145° and 148° W longitude. • Within the context of larger regional variation, local processes that operate on a scale of 10-100 km have great influence and serve to determine the function of the entire ecosystem. Episodic weather events and strong winds that blow through mountain passes have major effects on ocean physics and biological responses. Eddies influence vertical circulation and the movement of nutrients and organisms. Submarine canyons are important conduits between the basin and shelf, and the embayments that ring the Gulf of Alaska act as sources of nutrients and a refuge for marine organisms.
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2 0 1 7 – 2 0 1 8 B I E N N I A L R E P O R T
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