Inventory of fish species in the Bogachiel, Dosewallips, and Quinault river basins, Olympic National Park, Washington

Brenkman, Samuel; Corbett, Stephen; Sebring, Scott

Fish assemblages are a critical component of biological integrity from ecosystem and public interest perspectives and are good indicators of ecological health. In Olympic National Park (OLYM), fish populations are of recreational, aesthetic, and economic importance. Currently, there is little information on presence and spatial distributions of fish species in the upper portions of large watersheds in OLYM. This report summarizes a two-summer effort that included the first formal fish surveys in the Bogachiel, Dosewallips, and Quinault River Basins. Objectives of the study were to: 1) determine fish species composition and relative spatial distribution in tributaries to each basin during summer low-flow conditions; 2) assess extent of non-native fish and fish species of concern in the three basins; and 3) provide baseline information to guide future fish monitoring efforts. Secondary objectives were to determine seasonal trends in relative abundance of adult fishes in the Quinault River and determine incidence and prevalence of fish pathogens in fish inhabiting the Elwha River Basin. We conducted single pass electrofishing in 16 tributaries to the Bogachiel River, 10 tributaries to the Dosewallips River, 7 locations along the main stem Dosewallips, and 19 tributaries in the Quinault Basin. Thirteen fish species from 3 families (Salmonidae, Cottidae, and Catostomidae) and one subfamily (Coregoninae) were observed during the study. In the Bogachiel Basin, we observed 6 native fish species from 2 families including coho salmon, rainbow/steelhead trout, coastal cutthroat trout, riffle sculpin, shorthead sculpin, and torrent sculpin. Fifteen of 16 sampled tributaries in the Bogachiel Basin had fish, and sculpins were observed in 81% of the tributaries. In the Dosewallips Basin, only rainbow trout and non-native brook trout were observed upstream of Dosewallips Falls. We observed 12 fish species from 3 families in the Quinault Basin including Chinook salmon, coho salmon, sockeye salmon, native char, steelhead trout, coastal cutthroat trout, mountain whitefish, largescale sucker, prickly sculpin, shorthead sculpin, riffle sculpin, and torrent sculpin. In 2003, snorkel surveys in a 5 km reference site revealed low abundance of adult steelhead and adult Chinook; relatively high abundance of mountain whitefish; and the first observation of largescale suckers in the Park. Preliminary results from fish pathogen tests in the Elwha River revealed the presence of low levels of Bacterial-Kidney Disease in rainbow trout and brook trout. There was no evidence of bacterial or viral infections in any of >100 tested fish. This fish inventory is a thorough, yet incomplete, assessment of composition and relative distribution of fish species in 45 tributaries of 3 large river basins in OLYM. The detection of 13 fish species in 3 river basins was consistent with known distribution patterns for each species. The presence of non-native species was limited to observations of Eastern brook trout in the Dosewallips River, and native char were only observed in the Quinault Basin. Additional spatial and temporal sampling is necessary to document the full species assemblage in each basin. Distribution information will be essential in the development of monitoring efforts to detect trends in species distribution, frequency of occupancy, and species composition in OLYM wadeable streams. Information on species occurrence and spatial distribution also is necessary to understand ecological interactions among species, to address the extent of non-native fish invasions, and to make informed management decisions on fish resources.

Inventory of fish species in the Bogachiel, Dosewallips, and Quinault river basins, Olympic National Park, Washington

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