North Pacific Anadromous Fish Commission

Technical Report 15

Table of Contents

Southeast Alaska Pink Salmon Growth and Harvest Forecast Models

Authors:
James M. Murphy, Emily A. Fergusson, Andrew Piston, Steven Heinl, Andrew Gray, and Edward Farley

Abstract Excerpt:
Growth and harvest forecast models are used to provide insight into the role of temperature in the early marine ecology of Southeast Alaska (SEAK) pink salmon (Oncorhynchus gorbuscha). The onset of the Gulf of Alaska marine heatwaves in 2014–2015 (Bond et al. 2015) has highlighted the importance of understanding the resilience of salmon to a warming climate as the frequency and magnitude of marine heatwaves are expected to increase with warming Arctic conditions (Di Lorenzo and Mantua 2016). Pre-season harvest forecasts using adult pink salmon data have been a persistent challenge due to the presence of a single adult age and high variation in spawner-recruit relationships. Juvenile models have been developed to assist harvest forecasts for SEAK pink salmon (Orsi et al. 2016; Wertheimer et al. 2018; Murphy et al. 2019) using data collected during Southeast Alaska Coastal Monitoring Survey (SECM) (Murphy et al. 1999; Orsi et al. 2016; Fergusson et al. 2019) and have become the primary tool used for pre-season harvest guidance in SEAK pink salmon fisheries. Temperature is an important environmental covariate in the harvest forecast model, but it is unclear how it contributes to the forecast performance (Murphy et al. 2019). Although environmental conditions are often used to account for changes in survival, they also play an
important role in the distribution and migration of salmon. These two ecological processes are confounded within the harvest model as juvenile abundance is measured with catch-per-unit-effort (CPUE) data. Growth models are developed to provide ecological insight into the role of temperature in the early marine ecology of juvenile pink salmon. Otolith thermal mark recoveries of hatchery chum salmon are reviewed to provide insight into the overall migratory pattern of juvenile salmon in SEAK. Finally, run-size forecast models based on juvenile pink salmon abundance in the northern Bering Sea are included to add insight into critical periods in the marine survival of Alaskan pink salmon.

*This is the first paragraph of an extended abstract. Download the full abstract below.

DOI:
https://doi.org/10.23849/npafctr15/75.81.

Citation

Murphy, J.M., E.A. Fergusson, A. Piston, S. Heinl, A. Gray, and E. Farley.  2019.  Southeast Alaska pink salmon growth and harvest forecast models.  N. Pac. Anadr. Fish Comm. Tech. Rep. 15: 75–81.  https://doi.org/10.23849/npafctr15/75.81.