Monitoring riverine fish communities in the North Coast and Cascades Network: 2010 annual report

Brenkman, Sam; Boetsch, John; Kennedy, Philip

Rivers and streams draining from Olympic (OLYM) National Park are among the most protected corridors in the lower 48 states, and represent some of the largest tracts of undisturbed habitat in the range of several key Pacific Northwest fish species. Fishery resources in many park rivers are of high ecological and cultural importance, and contribute to economically important recreational, commercial, and tribal fisheries. This report summarizes fish communities monitoring in 2010. Monitoring objectives were to determine seasonal trends in 1) fish species composition; 2) relative abundance; and 3) extent of nonnative and hatchery fish in rivers during summer months. Annual sampling at monitoring sites insured that we accounted for the interannual variability in fish movement and abundance. Fish communities were monitored via snorkel surveys in ~5-km reference sites immediately upstream of the park boundary in 10 OLYM rivers from June-September. 351 snorkel surveys covering ~1,400 river km occurred from 2005- 2010; biologists observed 129,558 individual fish. The most surveys occurred in the N. F. Skokomish River (69). In 2010, 53 surveys occurred from June-September; biologists observed 28,600 individual fish and monitored 14 fish species. The maximum number of fish observations occurred in the E. F. Quinault (8,059) and Bogachiel (6,499) Rivers, with the fewest in the Elwha River (473) in 2010. In 2010, species compositions in the E. and N. Fork Quinault and S. F. Hoh Rivers had similar patterns where mountain whitefish (Prosopium williamsoni), cutthroat/rainbow trout (Oncorhynchus clarkii/Oncorhynchus mykiss), and bull trout (Salvelinus confluentus) had the highest percentages, respectively. The Sol Duc, N. Fork Sol Duc, and Dosewallips Rivers were dominated by trout during all summer months and mountain whitefish and trout comprised a majority of the assemblage in the Bogachiel, S. F. Calawah, and N. F. Skokomish Rivers. Species composition in all rivers in 2010 was consistent with patterns observed since 2005. No nonnative fish were observed in the 10 rivers in 2010 (28,600 obs.). Mountain whitefish peak counts were much higher than those for other fish species in 2010, and whitefish were the most abundant species in each river since 2005. Adult summer steelhead (Oncorhynchus mykiss) and Chinook salmon (Oncorhynchus tshawytscha) were critically low in abundance in all rivers from 2005- 2010. Annual trends in proportions of hatchery to wild salmonids were determined at reference sites. Extent of hatchery fish varied by river and species. In 2010, hatchery nonnative summer steelhead were detected in the Bogachiel, E. and N. F. Quinault, and S. F. Hoh Rivers. Hatchery Chinook were observed in the S. F. Hoh River. We did not detect hatchery coho (Oncorhynchus kisutch) salmon in reference sites in 2010 but they were observed in the S. F. Hoh in 4 of the last 6 years. The Sol Duc River contained all wild coho salmon (1,126 obs. since 2005). High numbers of stray hatchery summer coho, summer steelhead, and Chinook in the S. F. Hoh was surprising as the Hoh Basin does not receive hatchery plantings for those stocks. Sampling effort represented a balance of ecological considerations, sound monitoring, and practical limitations. This protocol allows NPS fisheries managers to detect abundance trends in high priority management species. Project data were used to 1) develop annual fishing regulations at OLYM; 2) meet in-park and ESA compliance 3) identify extent of nonnative and hatchery fish in OLYM; 4) leverage additional funds from USFWS, NPS, and Washington National Park Fund; and 5) communicate findings to diverse audiences.

Monitoring riverine fish communities in the North Coast and Cascades Network: 2010 annual report

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