Northwest Fisheries Science Center

Ocean ecosystem indicators of salmon marine survival in the Northern California Current

As many scientists and salmon managers have noted, variations in marine survival of salmon often correspond with periods of alternating cold and warm ocean conditions. For example, cold conditions are generally good for Chinook (Oncorhynchus tshawytscha) and coho (O. kisutch) salmon, whereas warm conditions are not.

These pages are based on our annual report of how physical and biological ocean conditions may affect the growth and survival of juvenile salmon in the northern California Current off Oregon and Washington.  We present a number of physical, biological, and ecosystem indicators to specifically define the term "ocean conditions."  More importantly, these metrics can be used for salmon survival outlooks 1–2 years in advance, as shown in Table 1.  This information is presented for the non–specialist; additional detail is provided via links when possible.

Map of transect areas sampled during reseach cruises of the coast of Oregon and Washington. Figure HP-01. Illustration of how basin-scale and local-scale physical forces influence the northern California Current and resultant food web structure. PDO = Pacific Decadal Oscillation. NPGO = North Pacific Gyre Oscillation. ENSO = El Niño–Southern Oscillation. Figure from Peterson et al. 2014 Oceanography 27(4):80-89.

Material presented on this website has two sources. One is the World Wide Web, from which we have drawn values for the Pacific Decadal Oscillation, ENSO/ONI (Oceanic Niño Index), Upwelling Index, and sea surface temperatures. Links and references to these sources are given in the respective sections that deal with these four physical variables. All other data are from our direct observations during a) biweekly oceanographic sampling along the Newport Hydrographic Line and b) annual juvenile salmonid surveys conducted in June and September. Survey station locations, sampling and survey methods are presented under "Ocean Sampling Methods" (see left-side menu).

 Using these data, we developed a suite of ocean ecosystem indicators upon which to base outlooks of salmon returns.  These outlooks are presented as a practical example of how ocean ecosystem indicators can be used to inform management decisions for endangered salmon. We provide a qualitative ‘stoplight’ table where we rate each indicator in terms of its "good," "bad," or "neutral" relative impact on salmon marine survival (Table 1). We also use these ocean ecosystem indicators to predict adult salmon returns which complement other methods, such as jack returns, smolt–to–adult return rates (Scheuerell and Williams 2005), and the  The next link/button will exit from NWFSC web site Logerwell production index

The strength of this approach is that biological indicators are directly linked to the success of salmon during their first year at sea through food–chain processes.  These biological indicators, coupled with physical oceanographic data, offer new insight into the mechanisms that lead to success or failure for salmon runs.

In addition to salmon return outlooks, the indicators presented here may be of use to those trying to understand how variations in ocean conditions might affect recruitment of fish stocks, seabirds, and other marine animals.  We reiterate that trends in salmon survival track regime shifts in the North Pacific Ocean, and that these shifts are transmitted up the food chain in a more–or–less linear and bottom–up fashion as follows:

upwelling → nutrients → plankton → forage fish → salmon.

The same regime shifts that affect Pacific salmon also affect the migration of Pacific hake and the abundance of sea birds, both of which prey on migrating juvenile salmon.  Therefore, climate variability can also have "top down" impacts on salmon through predation by hake and sea birds (terns and cormorants).  Both "bottom up" and "top down" linkages are explored here.

Information on this page is coordinated and organized by the following NWFSC Fish Ecology staff: 

Bill Peterson Late Oceanographer, Newport Field Station
Kym Jacobson Research Zoologist, Newport Field Station
Brian Burke, Research Fisheries Biologist
JoAnne Butzerin Technical Writer/Editor

And the following Cooperative Institute for Marine Resources Studies ( The next link/button will exit from NWFSC web site CIMRS) staff:

Jennifer Fisher Senior Research Assistant, Oregon State Univ.
Cheryl Morgan Senior Research Assistant, Oregon State Univ.
Samantha Zeman Research Assistant, Oregon State Univ.