"A widespread decrease in productivity of sockeye salmon on the west coast of North America" Randall M. Peterman 1 and Brigitte Dorner 2 1 School of Resource and Environmental Management (REM), Faculty of Environment, Simon Fraser University, Burnaby, British Columbia 2 Driftwood Cove Designs Lasqueti Island, British Columbia Salish Sea Ecosystem Conference, Session 9B 25-27 October 2011 1
Background Fraser River sockeye salmon - 2009 returns: lowest since 1947 - Since early 1990s, have had decreases in -- Abundance (adult returns) -- Productivity (adult returns per spawner) 2
Total Fraser Sockeye, 4-yr moving average Adult returns per spawner Trends differ among stocks Return year 3 M. Lapointe, PSC
Total Fraser Sockeye, 4-yr moving average (moving 4 yr avg.) Adult returns per spawner Return year Return year Return year 4 M. Lapointe, PSC
Research objective How widespread has decreasing productivity been among 64 west-coast sockeye populations? - Mostly wild stocks - 24 stocks with smolt or fry abundances Salish Sea Peterman and Dorner 2011 5
Methods Measures of productivity 1. Annual adult returns per spawner 2. "Kalman filter" smoothed values of #1 that account for: - Density-dependent effects of spawner abundance - Measurement error - Reduces "noise" Analyses - Model comparisons based on AIC c (Larkin vs. Ricker) - Cross-correlations - Principal components analysis -Clustering 6
Results - Widespread decreases in productivity, especially since 1990s -Notunique to Fraser River Salish Sea Peterman and Dorner 2011 7
Fraser River (Early Stuart) Sockeye Recruits per spawner Recruits per spawner 20 15 10 5 0 1950 1960 1970 1980 1990 2000 Year of spawning Brood year (brood year) Then we standardized time series for comparisons across stocks (mean = 0, SD = 1) 8
Standardized productivity (Kalman filter at scaled in SDUs, best model) Fraser Early Stuart Year of spawning Fraser Early Summer Year of spawning Harrison Pitt (hatch.) Peterman and Dorner 2011 9
Standardized productivity (Kalman filter at scaled in SDUs, best model) Fraser Early Stuart Fraser Summer Fraser Early Summer Year of spawning Harrison Pitt (hatch.) Year of spawning 10 Peterman and Dorner 2011
Standardized productivity (Kalman filter at scaled in SDUs, best model) Fraser Early Stuart Fraser Summer Fraser Early Summer Fraser Late Harrison Pitt (hatch.) Year of spawning 11 Peterman and Dorner 2011
Wash. & Barkley Sd., B.C. Central Coast B.C. Standardized productivity (Kalman filter at scaled in SDUs, best model) North Coast B.C. S.E. Alaska Year of spawning 12 Peterman and Dorner 2011
Yakutat Pen., Alaska Year of spawning 13 Peterman and Dorner 2011 Standardized productivity (Kalman filter a t scaled in SDUs, best model)
Harrison Sockeye Productivity Productivity (adult returns per Productivity spawner) (adult returns per spawner) Productivity (adult returns per spawner) Harrison Return year - Enter Salish Sea as smolts - Use Johnstone Strait - Enter Salish Sea as fry - Later migrants - Use Juan de Fuca Strait? 14 M. Lapointe, PSC
Conclusions 1. Similar decreases in productivity along west coast suggest that main causes are most likely shared and are outside of Salish Sea. 2. From juvenile data: - Most of mortality that caused decreases occurred in post-juvenile stage (still possibly freshwater origin) 3. Possible mechanisms -Predation - Food - Pathogens - Climate-driven changes in these (reflected by SST) -...? 15 Peterman and Dorner 2011
Recommendations 1. Place research priority on large-scale processes 2. Create Canada-U.S. sockeye working group - Multi-disciplinary research program -- Life history of juveniles (Harrison vs. others) -- Oceanography -- Food, predators, pathogens, harmful algae,... - Shared data base for entire west coast 3. Estimate juvenile abundance on more stocks Reference Peterman, R.M. and B. Dorner. 2011. Fraser River sockeye production dynamics. Cohen Commission Technical Report 10: 133 pp., see www.cohencommission.ca 16