Complete Description of Coastal Ocean
Habitat Use by Chinook Salmon
Current Status of Accomplishment or Milestone: Although this work is continuing, a paper entitled "Behavior of Maturing Chinook Salmon in Coastal Waters of the California Current as Shown by Archival Tagging" was presented at an American Fisheries Society meeting on the currently available data and a manuscript is in preparation.
Background: Relatively little is known about the ecology of salmon in the open ocean. Several studies, including those at PFEL, have demonstrated the importance of ocean conditions on interannual variability in ocean survival; but the mechanisms of how the environment affects salmon require further evaluation. The advent of new technologies in the form of archival tags provides the potential to collect specific information on how salmon use the ocean environment. Demonstration studies in the open ocean have shown that salmon have specific diel behavior patterns and use the environment in specific ways.
Purpose of Activity/Goal of Project: The goal of this study is to evaluate ocean habitat use and behavior of chinook salmon in the coastal waters of the California Current. An ancillary goal is to develop the techniques so they can be applied to listed species, such as coho salmon, with knowledge of potential impacts.
Description of Accomplishment and Significant Results: Archival tags recording temperature and depth were placed on subadult and maturing chinook salmon off central and northern California. Seven tags (out of 28 deployed) were recovered between October 2000 and May 2001. Four recoveries were made in rivers or estuaries and three in the ocean. Results demonstrated the temperature and depth ranges occupied by chinook salmon in this part of their range, as well as diel behavior patterns that differ from those of other salmon in the open ocean North Pacific. Fish generally move to shallower water near dawn and dusk, likely associated with foraging. Behavior appears to be modulated by physical conditions. These data provide the first longer term information on behavior and habitat of chinook salmon in coastal waters. Continued tagging is underway to discern the roles of season, age, and sex; tagging near the extremes of the species’ range may help elaborate habitat preferences.
Significance of Accomplishment (e.g., to the Center, to Management, and to NMFS Strategic plan Goals): Understanding how salmon use the ocean environment will enable scientists to improve the value of correlational studies between environmental variability and salmon survival, assisting with the recovery process.
Problems: None
Key Contact: Franklin B. Schwing, (831-648-9034, Franklin.Schwing@noaa.gov)