Research

Aquatic Ecosystems: Current Research

Smolt-to-Adult Survival of Puget Sound and Coastal Coho Salmon

People Involved

• Nate Mantua (contact person), UW Climate Impacts Group (CIG)
• Dave Seiler, Washington Department of Fish and Wildlife, Science Division
• Jeffrey Haymes, Washington Department of Fish and Wildlife, Coho Program Manager

Background

At present, coho salmon managers need to make stock-specific pre-season run-size forecasts in order to set allocations and harvest rates for fisheries around the state. These forecasts are primarily based on the return rates for "jacks", precocious male coho that return to their streams or hatcheries of origin after just one summer at sea (typically, adult coho spend about 18 months and two full summers at sea). Jack return rates have served as relatively reliable predictors for adult returns the next year, but there are numerous "outlier" periods when the jack/adult return relationships change.

This study aims to identify and better understand the role of environmental change in changing coho return rates. Washington's Department of Fish and Wildlife has a unique collection of wild and hatchery coho salmon marine survival data covering up to 25 years for streams and hatcheries throughout western Washington. In this study, data for five wild and seven hatchery stocks are being examined for the spatial and temporal patterns of variability, and how those patterns relate to the regional climate history.

Research Goals

• Improve our understanding for environmental influences on coho marine survival for wild and hatchery coho salmon
• Improve our understanding for the environmental factors that influence coho marine survival on the Washington coast and in Puget Sound
• Develop empirical models that can use environmental data to skillfully estimate coho marine survival rates prior to the time that harvest management decisions are made
  

Selected References

For more publications on CIG's research on climate and aquatic ecosystems, please see CIG Publications.

Seiler, D., G. Volkhardt, S. Neuhauser, P. Hanratty, L. Kishimoto, P. Topping, M. Ackley. 2003. 2003 wild coho forecasts for Puget Sound and Washington Coastal Systems. Washington Department of Fish and Wildlife Science Division. Olympia, Washington.

Logerwell, E. A., N. J. Mantua, P. Lawson, R. C. Francis, and V. Agostini. 2003. Tracking environmental processes in the coastal zone for understanding and predicting Oregon coho (Oncorhynchus kisutch) marine survival. Fisheries Oceanography 12(3):1-15.