North Pacific Anadromous Fish Commission

Technical Report 18

Table of Contents

Coastal Surveys in Alaska and Their Application to Salmon Run-Size and Harvest Forecasts

James M. Murphy, Sabrina Garcia, Andrew Piston, Jamal H. Moss, Kathrine Howard, Emily A. Fergusson, Wesley W. Strasburger, Steve Heinl, Sara Miller, Elizabeth Lee, Richard Brenner, Zachary Liller, Andrew Gray, and Ed Farley

Abstract Excerpt:
Understanding the factors that influence the survival of salmon is important as salmon play a key role in the ecological and socio-economic framework of many communities throughout Alaska. The marine survival of salmon is believed to be determined during key critical periods (Beamish and Mahnken 2001). The first critical period occurs during the estuarine or initial marine period of salmon. Predation-based mortality can often be the key factor during this critical period of salmon. The second critical period is believed to be primarily dependent on the ability of salmon to reach a critical size or nutritional state required to survive marine winters (Beamish and Mahnken 2001). Nutritional-based sources of mortality will begin to increase in importance as salmon outgrow the predation size window of most marine predators. Coastal surveys that provide information on the abundance and ecology of juvenile salmon can add insight into the relative importance of these critical survival periods as well as the resilience of salmon to changes in marine ecosystems, such as the emergence of marine heatwaves (Barbeaux et al. 2020) and warming of Arctic habitats (Jones et al. 2020). Coastal marine surveys in Southeast Alaska (SEAK) and the northern Bering Sea (NBS) currently use juvenile salmon abundance to provide harvest forecasts for pink salmon fisheries in SEAK and adult run-size forecasts for Chinook salmon fisheries in the Yukon River. Significant relationships between juvenile (first summer at sea) and adult abundance are present in both surveys, which emphasizes the importance of the early life-history stages (freshwater and initial marine life-history stages) of salmon to structuring future adult returns.

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Murphy, J.M., S. Garcia, A. Piston, J.H. Moss, K. Howard, E.A. Fergusson, W.W. Strasburger, S. Heinl, S. Miller, E. Lee, R. Brenner, Z. Liller, A. Gray, and E. Farley.  2022.  Coastal surveys in Alaska and their application to salmon run-size and harvest forecasts.  N. Pac. Anadr. Fish Comm. Tech. Rep. 18: 140–146.