Evaluate Impact of Oceanic Variability on Salmon
Populations in the Pacific Northwest
Current Status of Accomplishment or Milestone: Initial research completed, manuscripts in press and review, research continuing.
Background: It is well established that interdecadal variability in oceanic conditions in the north-east Pacific is closely related to interdecadal trends in salmon production. Recent work at PFEL has also demonstrated good interannual relationships between the dynamics of coastal waters in the Pacific Northwest and coho salmon (Oncorhynchus kisutch) production, but it was unclear whether the identified relationships would hold to dates preceding regime shifts in the mid-1970s when survival rates and ocean conditions were different. Research has been conducted on several scales and using different approaches to evaluate whether the relationships hold over longer time periods.
Purpose of Activity/Goal of Project: To evaluate the relationship between coho salmon production and coastal ocean parameters over longer time scales and to examine whether they can be used to provide relevant forecasting information useful to management.
Description of Accomplishment and Significant Results: Short term analyses using available remote sensing ocean data established the initial relationships of coho survival and ocean conditions. These were compared to other sources of NOAA data that extend back in time further than remotely sensed data, although on coarser spatial scales. Smolt to adult survival from the Oregon Production Index region was examined, and relationships were derived for an Early Marine Phase (EMP) and Late Marine Phase (LMP) period. For both types of data, the models derived from the regressions accounted for over 90% of the interannual variation in survival, and predicted good survival for the 1999 ocean entry year class. Long term analyses were also run from 1967 to 1998 using different EMP variables and LMP variables. These longer models accounted for 79% of the inter-annual variation in coho survival, and also predicted good survival for the 1999 ocean entry year class. The long-term models indicate that coho salmon survival can be successfully modelled across regime shifts, but for both the long term and short-term models actual survival fell short of that predicted for the 1999 ocean entry year class; nonetheless, strong survival in Columbia River stocks has continued into 2001 for the 2000 ocean entry year class.
Significance of Accomplishment (e.g., to the Center, to Management, and to NMFS Strategic plan Goals): An important goal of NOAA's strategic plan element on recovering protected species is to evaluate natural influences and fluctuations. The results evaluate not only how ocean variability impacts coho survival historically but develops an approach to predict ocean survival.
Problems: None.
Key Contact: George Boehlert (831-648-8515; george.boehlert@noaa.gov)