Juvenile salmonid habitat of the Redwood Creek basin, Humboldt County, California

Graduation Date

1988

Document Type

Thesis

Program

Other

Program

Thesis (M.S.)--Humboldt State University, Fisheries, 1988

Committee Chair Name

Richard Ridenhour

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Humboldt State University -- Theses -- Fisheries, Humboldt County, Habitat, Redwood Creek, California, Fishes, Salmonidae

Abstract

During the summer-fall periods of August 4 to October 12, 1980 and August 13 to 21, 1981, the streams of the Redwood Creek basin, Humboldt County, California were surveyed to describe and characterize the salmonid rearing habitat and distribution of juvenile salmonids. Twelve streams throughout the basin, 10 east-west paired tributaries and Prairie and Redwood Creeks, were intensively sampled August 24 to October 5, 1981, to measure biotic and physical parameters. The basin was divided into east and west sides, the Prairie Creek basin, and the lower, middle, and upper basins for the purposes of comparison. Salmonid fish occurred in 58 (52 percent) of the 111 tributaries sampled for fish. Juvenile steelhead were most common and widely distributed. Cutthroat trout and coho salmon primarily occurred in the Prairie Creek system. Most fish occurred in streams with flows greater than 3 1/s (0.1 cfs). The westside tributary 0+ steelhead mean lengths (mm) and weights (g) were significantly larger than those of the eastside tributaries. There were no east-west or north-south trends in fish population estimates, fish per m2, or salmonid grams per m2. The eastside streams, which generally had lower flows, had larger numbers of fish per unit flow. Measured water parameters were flow (1/s), alkalinity (mg CaCO3/1), pH, specific conductivity (mmhos @ 25 °C), dissolved oxygen (ppm), and temperature (°C). All eastside mainstem basin sections had lower mean flows than their adjacent westside sections. The Prairie Creek basin had the highest mean flow, the upper eastside basin the least. Mean alkalinity and pH of nine study sites sampled were 35 mg CaCO3/1 and 6.9, respectively. Specific conductivity values were higher in the upper basin and eastside basin sections. There was a south to north trend of decreasing values on both sides of the basin. Mean basin tributary specific conductivity was 133 mmhos (S.D. = 84). Tributary dissolved oxygen values were generally in the 9-10 ppm range, and between 7-9 ppm in the mainstem of Redwood Creek. Maximum measured water temperatures ranged from 10.5 °C to 23.0 °C for the tributaries and 14.0 °C to 26.0 °C for Redwood Creek. The surface water temperatures of mainstem Redwood Creek were generally hotter in the middle basin, and cooler in the headwaters and lower basin. Twenty-four hour drift samples revealed the westside tributaries to generally have larger numbers of individual drift organisms, drift density (number of individuals/100 m3), richness, number of taxa, and terrestrial invertebrate contribution to drift than the eastside tributaries. The eastside tributaries had significantly greater diversity (H') and evenness values than the westside tributaries. The major insect orders contributing the greatest number of organisms to drift samples were Diptera, Ephemeroptera, Trichoptera, and Coleoptera. Drift organism composition showed decreasing ephemeropterans and increasing dipterans from north to south. Similarity indices of drift samples amongst the 12 streams ranged from 0.81 to 0.41. Comparisons of mean similarity indices between streams were usually nonsignificant, with the exception of the Redwood Creek site. Redwood Creek had the lowest mean similarity index, 0.52. The study showed the character of each stream as a single entity, determined baseline rearing habitat conditions, and can serve as the basis for future evaluation of the rearing habitat and watershed rehabilitation efforts.

https://scholarworks.calstate.edu/concern/theses/sj139468f

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