IV. Ocean Influences on Salmon and Crab Populations

Collaborators:

• John Largier - Scripps Institution of Oceanography
• Alan Hastings - University of California, Davis
• Mark Hill - University of California, Davis
• Cathryn Lawrence - University of California, Davis

Current Funding:

National Science Foundation (GLOBEC)

Focus:

Influence of physical conditions in the California Current on salmon (coho and chinook) and Dungeness crab populations.

We have a long history of research on Dungeness crab population dynamics (in particular their cyclic behavior) and some on California populations of salmon. Also, we recently showed that salmon populations in the Columbia River covaried in a pattern reflecting the three basins (Botsford and Paulsen 2001).

A major recent result is the identification from catch data of ecosystem forcing of California Current coho and chinook salmon and Dungeness crab (Fig.1) by what we called a California Current Index (CCI). The latter is an EOF (i.e., principal component) of ocean temperature, sea level, and upwelling index, which explains more than 50 percent of the variability at each location, in each season, and represents ENSO conditions (Fig.2) .While these populations were subject to common forcing, they responded differently: coho salmon responded on annual time scales, coherently along the coast, and collapsed in the mid-1970s; chinook salmon responded on 3-4 year time scales with a spatial pattern, and did not collapse in the mid-1970s; and Dungeness crab responded on a 10-year time scale, synchronously along the coast (except San Francisco and Monterey which collapsed in the late 1950s). The CCI covaries with other decadal scale indicators of physical conditions in the northeast Pacific (Fig.3) . (see section on Marine Conservation below for additional results regarding status of these salmon populations).