Linkages between climate, growth, competition at sea, and production of sockeye salmon populations in Bristol Bay, Alaska, J. Nielsen (USGS) & G. Ruggerone (NRC)

North Pacific Ocean – a Highly Productive Ecosystem 2002 U.S. North Pacific exvessel harvest value = $1.13 billion Pacific Rim Salmon Runs,

Climate Change and North Pacific Salmonid Species Abundance Shifts

Regime Shift Impacts on Marine Populations Compiled by D. L. Alverson (NRC)

Eastern North Pacific Winter Sea Surface Temperature

Bristol Bay Sockeye Salmon Run,

Key Question What biological and physical climatic feedback mechanisms have influenced historic and current abundance patterns in Bristol Bay sockeye salmon?

New Use for an Old Tool: Salmon Scales

Salmon Size Related to Scale Radius Davis et al. 1990; Zimmerman 1991

Sockeye salmon growth using salmon scale annuli & circuli measurements

Ocean Carrying Capacity Hypotheses  Greater salmon abundance is related to greater early marine growth in coastal waters.  Greater salmon abundance is associated with reduced growth during older life stages (density-dependence).  Competition during freshwater & marine life-stages can reduce growth and survival.  Highly migratory salmon may compete with conspecifics originating from distant natal rivers. Peterman 1984; Ishida et al 1993; Rogers & Ruggerone 1993; Welch & Parsons 1993; McKinnell 1995; Pyper & Peterman 1999; Pearcy et al. 1999

Kvichak Sockeye Growth During First Two Years at Sea

Salmon Abundance Linked to Early Ocean Growth,

Kvichak Sockeye Growth During Third Year at Sea: Density-dependent

Asian pink salmon are highly abundant during odd numbered years. Bristol Bay sockeye salmon overlap with Asian pink salmon during their 2nd and 3rd years at sea. Pink and sockeye salmon have similar diets on high seas. Food consumption of both species declines in odd yrs. Sockeye diet changes more than pink diet in odd-yrs. Few wild or hatchery pink salmon originate from Bristol Bay. Facts Supporting Competition Hypothesis

Eastern Kamchatka Pink Salmon Runs,

Hatchery Pink Salmon Release

Overlap of Asian pink & Bristol Bay Sockeye salmon

Sockeye growth reduced during odd years at sea (2nd & 3rd yrs)

Asian Pink Salmon Affect Adult Sockeye Length,

Smolt to Adult Survival, %-26%

59 Million Fewer Sockeye, (>$310 million)

Implications of Feedback between Global Change & Competition Effect on Salmon Survival Climate feedback processes can impact salmon production on multiple scales. Climate change influence on local production of salmon may have unintended impacts on distant stocks. Natural and anthropogenic fluctuations in salmon production and shifts in food web dynamics may impact ESA protected salmon species throughout the North Pacific Ocean. These findings provide evidence of the need for “salmonid ecosystem management” looking at both freshwater and marine feedback patterns in salmon.

Acknowledgements: E. Farley, P. Hagen, B. Agler, J. Meka, D. Rogers, K. Myers, S. Ignell, M. Zimmerman