Adult Escapement Monitoring Program Summary 2004-2005

Reichmuth, Michael; Ketcham, Brannon; Fong, Darren

Olema Creek, Redwood Creek, and Pine Gulch Creek are the largest undammed watersheds in coastal Marin County, California and are important streams for threatened coho salmon (Oncorhynchus kisutch) and steelhead trout (O. mykiss) within the central California coast Evolutionarily Significant Unit (CCCESU). The National Park Service (NPS) has conducted adult escapement surveys in Marin County watersheds since 1994. NPS results show that these watersheds have supported annual runs of coho ranging from less than 10 to more than 200 individuals. This report presents annual summary information of adult escapement results for the 2004-2005 spawning season for Olema, Pine Gulch, Redwood, and Cheda Creek. Winter 2004-2005 represented record spawner numbers for most watersheds in coastal Marin County. Adult escapement estimates and redd totals nearly doubled from last generation of this year class in Spawner Year (SY) 2001-02. The Peak Live plus cumulative Dead (PLD) estimate and redd counts in Olema Creek (182 coho and 92 redds), John West Fork (86 coho and 45 redds), and Redwood Creek (171 coho and 93 redds) represented the highest counts recorded in the past decade of monitoring. Consistent with these record results, MMWD reported an estimated 1800 coho spawners and 496 redds for the Lagunitas Creek watershed (excluding Olema Creek), up from 286 redds and 735 live coho in SY 2001-02 (MMWD 2005). The patterns represented in our monitoring data suggest regional influences on the coho salmon escapement observed over the past decade. Overall coho escapement within Marin County watersheds has been trending upward since the 1997-98 ENSO event likely triggered the Pacific Decadal Oscillation (PDO), shifting the dominant productivity from the Alaska Current to the California Current in the late 1990s. Since 1999, all three coho year classes in Olema Creek and Redwood Creek have shown a strong response to these changed ocean productivity patterns. This upward trend is most prominent in the documented return of coho salmon to the Pine Gulch Creek watershed in winter 2000-2001. All monitored watersheds show the pattern of two stronger year classes SY 2003-04 (Year Class 1) and SY 2004-05 (Year Class 2), and one weak year class, SY 2005-06 (Year Class 3). The strongest year class prior to the 1997-98 ENSO event, we surmise that Year Class 3, was severely impacted as fish attempted to overwinter during the El Nino winter. As a result, anticipated coho escapement for SY 2005-06 is less than that observed the past two years. This research is conducted under the Endangered Species Act Section 10 Permit #1046 authorization managed by NOAA - Fisheries. Funding to support monitoring activities was provided through the National Park Service - San Francisco Area Network Inventory and Monitoring Program and the California Department of Fish and Game Fisheries Restoration Grant Program Contract P0330431.

Adult Escapement Monitoring Program Summary 2004-2005

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