Document Type

Article

Journal/Book Title/Conference

North American Journal of Fisheries Management

Volume

14

Issue

2

Publisher

American Fisheries Society

Publication Date

1994

Keywords

summer, habitat use, littoral zone fishes, Lake Tahoe, effects, shore zone structures

First Page

385

Last Page

394

Abstract

We used scuba observations to determine summer habitat use and the effects of piers on the littoral-zone fish community in Lake Tahoe, California–Nevada. Habitat complexity declined with depth. Over 50% of the littoral zone less than 2 m deep was composed of complex boulder substrates, but this substrate represented less than 10% of the habitat between 10 and 18 m deep. A severe drought lowered the surface elevation of the lake 2 m and reduced the wetted complex rocky habitat by 20% between the 0- and l0-m isobaths (referenced to the mean lake level of 1,899 m above sea level). The dominant littoral-zone fish, adult Lahontan redsides Richardsonius egregius, were found at depths ranging from 1–10 m over substrates, but at somewhat greater depths (3–10 m) over cobble–boulder substrates. Juvenile Lahontan redsides were concentrated around boulders at depths of 1–3 m, and their densities were much lower than the densities of adults. Adult tui chub Gila bicolor and rainbow trout Oncorhynchus mykiss were also most often associated with complex boulder habitats. The daytime densities and species composition of fishes associated with piling-supported piers did not differ significantly from adjacent no-pier areas, whereas the densities of Lahontan redsides, tui chubs, Lahontan speckled dace Rhynichthys osculus robustus, and Tahoe suckers Catostomus tahoensis associated with the complex structure of rock-crib piers were significantly higher than in adjacent no-crib areas. Fish density increased 5–12-fold at night relative to the observed daytime densities in the pier, rock-crib, no-pier, and no-crib transects.

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