How do we know how many salmon returned to spawn? Implementing the California Coastal salmonid monitoring plan in Mendocino County, California

Abstract

California's coastal salmon and steelhead populations are listed under California and Federal Endangered Species Acts; both require monitoring to provide measures of recovery. Since 2004 the California Department of Fish and Game and NOAA Fisheries have been developing a monitoring plan for California¡¯s coastal salmonids (the California Coastal Salmonid Monitoring Plan- CMP). The CMP will monitor the status and trends of salmonids at evolutionarily significant regional scales and provide population level estimates. For the CMP, data to evaluate adult populations are collected using a spatially balanced probabilistic design (e.g., Generalized Random Tesselation Stratified- GRTS). Under this scheme a twostage approach is used to estimate status. Regional redd surveys (stage 1) are conducted in stream reaches in a GRTS sampling design at a survey level of 15 percent or ¡Ý 41 reaches, which ever results in fewer reaches, of available habitat each year. Spawner: redd ratios are derived from smaller scale census watersheds (stage 2) where "true" escapement is estimated using capture-recapture methods. These are used to estimate regional escapement from expanded redd counts. In 2008 and 2009 we applied the results of our previous studies to estimate salmonid escapement for the Mendocino coast region, the first implementation of the CMP in the state. Here we present the results of the first 3 years of this monitoring effort and discuss our findings in context of expanding the CMP to all of coastal California. We discuss sample frame development, sample size, and present escapement data for six independent and eight potentially independent populations and two Diversity Strata within the Central California Coho Salmon Evolutionarily Significant Unit.

Parent Publication

• Proceedings of the coast redwood forests in a changing California: A symposium for scientists and managers

Citation

Gallagher, Sean P.; Wright, David W. 2012. How do we know how many salmon returned to spawn? Implementing the California Coastal salmonid monitoring plan in Mendocino County, California. In: Standiford, Richard B.; Weller, Theodore J.; Piirto, Douglas D.; Stuart, John D., tech. coords. Proceedings of coast redwood forests in a changing California: A symposium for scientists and managers. Gen. Tech. Rep. PSW-GTR-238. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture. pp. 409-418.