North Pacific Anadromous Fish Commission

Technical Report 15

Table of Contents

Ecosystem Indicators Development for Coho and Chinook Salmon

Authors:
Kathryn Sobocinski, Correigh Greene, Neala Kendall, Joe Anderson, Mara Zimmerman, and Michael Schmidt

Abstract Excerpt:
Recent work on Chinook and coho salmon and steelhead trout has shown a decline in the marine survival of Salish Sea populations that was not evident in populations from coastal regions (Zimmerman et al. 2015; Ruff et al. 2017; Kendall et al. 2017). The causes of this decline in marine survival are likely complex, and may include bottom-up processes that drive prey availability, top-down processes, including increasing abundances of predators that may be exacerbating mortality, as well as a multitude of anthropogenic factors such as habitat loss, contaminants, and hatchery management practices that may contribute to disease, reduced fish condition, and ultimately increased mortality. The cumulative effects of these factors are unknown. Previous work showed that for Chinook, a single oceanographic climate index (North Pacific Gyre Oscillation) did not perform well in explaining survival patterns (Ruff et al. 2017). Recent work on the development of indicators of Puget Sound steelhead survival showed that predator abundance, patterns in hatchery releases, and timing of freshwater input, as well as oceanographic conditions, were informative in predicting marine survival (Sobocinski et al. in review). While the three species with observed declines in marine survival (Fig. 1) have different life-histories, and are therefore subjected to variable pressures at multiple scales, there are some commonalities in factors explaining marine survival over the 40-year time period from the late 1970s to present.

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

DOI:
https://doi.org/10.23849/npafctr15/126.128.

Citation

Sobocinski, K., C. Greene, N. Kendall, J. Anderson, M. Zimmerman, and M. Schmidt.  2019.  Ecosystem indicators development for coho and Chinook salmon.  N. Pac. Anadr. Fish Comm. Tech. Rep. 15: 126–128.  https://doi.org/10.23849/npafctr15/126.128.