What can long-term paleolimnological records of sockeye salmon dynamics tell us?

Since the validation of an approach to track past sockeye salmon dynamics (Finney et al. 2000), we have made numerous advancements in our understanding regarding the tempo of change and the impact of such changes on freshwater systems. For example, long-term records reveal that the dynamics captured in the historical monitoring period are insufficient to fully appreciate the rate of change in the population size of sockeye salmon (Finney et al. 2002; Schindler et al. 2006). Our current research is focused in four areas: 1) expanding the spatial extent of our records and developing predictive models to identify sites where the salmon signal will not be confused by other factors; 2) analyzing records that extend back into the mid-Holocene warm period; 3) developing stronger inferences of the drivers of salmon dynamics over these longer periods; 4) defining the response of inland communities to this shifting landscape of resource abundance. Our Holocene records reveal that the centennial-scale dynamics first uncovered in the ~2000 year records (Finney et al. 2002) are truly periodic and have played out in the past. By pulling together a suite of environmental records (including microchemistry analyses of otoliths), we are reconstructing local and regional conditions and are quantifying the variance explained by these records in our salmon inferences. Overall, our research has shown that in the absence of large-scale human interventions, sockeye salmon is a resilient fish. Where populations have gone extinct is at the southern end of their range; a region where human impacts are most intense.