A two-day workshop was convened October 8-9, 2008 to review and synthesize sediment core studies conducted in sockeye salmon (Oncorhynchus nerka) nursery lakes in British Columbia, Alaska, and the northwest United States.
The objective of the workshop was to advance our understanding of paleolimnological applications and what these techniques can tell us about long-term changes in salmon escapements and lake ecology relative to salmon harvesting and climate change. Seven talks were presented on topics including a background to paleolimnology techniques for salmon nursery lakes, the roles of salmon-derived nutrients in lake ecosystems, the utility and pitfalls of salmon escapement data for referencing sediment core time-series data, and the influence of watershed processes and nitrogen budgets on salmon-derived nutrient signals in lake sediments. Eight talks presented case studies of paleolimnological data from British Columbia and Alaska sockeye salmon nursery lakes and a coastal riparian forest. The workshop concluded with a panel discussion to critically evaluate the potential application of paleolimnological techniques to the management of sockeye salmon. Recommendations were made that define how and where paleolimnological techniques are most likely to contribute to a practical understanding of sockeye salmon ecology and management. These recommendations include the need to formulate questions about sockeye salmon ecology that a paleoecology study of a nursery lake can realistically answer. Preliminary lake nitrogen budgets and consideration of the limitations of historic salmon population data will help determine whether salmon likely leave a detectable d15N signal in the sediments. Multi-proxy suites of paleoindicators and an understanding of how sediment deposition and filtering processes alter the sediment record in a given lake are required to interpret variations in sediment signals. A reference lake system and the fitting of nitrogen mixing models are also needed to interpret the d15N paleorecord for salmon escapements. Managers need to weigh paleoecological approaches against the costs and constraints of long-term fish population monitoring to be convinced that paleotechniques are worth the investment.
Download the paper: Applications of paleolimnology to sockeye salmon nursery lakses (PDF)