The composition of Lake Tahoe's fish community has changed considerably since the arrival of Euro-Americans to the Lake Tahoe Basin. Prior to the influence of Euro-American activities, seven species of fish occurred in the lakes and streams of the Lake Tahoe Region (Murphy and Knopp 2000
). Of the native fish species, Lahontan cutthroat trout (Oncorhynchus clarki henshaw
i) and the mountain whitefish (Prosopium williamson
i) were abundant and revered by Native Americans because they provided ample food for their people. Today, Lahontan cutthroat trout have been extirpated from Lake Tahoe, and the population of mountain whitefish is believed to occur in very low numbers (Murphy and Knopp 2000
). Several factors have contributed to the decline or extinction of native fish and the degradation of fish habitat in the Lake Tahoe Region. Extensive logging, water diversions, intense grazing, commercial harvest, road building, and the introduction of non-native fish and other aquatic organisms are believed to have cumulatively contributed to the change in Lake Tahoe's fish composition and degradation of fish habitat (SNEP 1996
, Murphy and Knopp 2000
). Consequently, since the Comstock Era (circa
1860), 20 additional species of fish have been introduced into Lake Tahoe's aquatic communities (TRPA 2001 Threshold Evaluation, Appendix 1
There are two key aquatic environments that support fish in the Lake Tahoe Basin, lakes and streams. These two ecosystems are dynamic and characteristically change in space and time. Combined, attributes of lakes and streams provide necessary elements such as water, cover, and spawning and nursery habitat to support fish. Both environments play an important role in sustaining desirable fish populations and cannot be viewed independently because some fish species use both lake and stream environments to fulfill their life cycles. The combination of chemical, biological, temperature, and physical characteristics of lakes and streams influence the suitability of these environments to sustain different fish populations. Accordingly, degradation of any of these necessary lake and stream characteristics can reduce the sustainability of Tahoe's fishery.
Since 1996, limited data has been collected for assessing stream habitat conditions. The Tahoe Regional Planning Agency (TRPA
) Project Review personnel have tracked water diversions and changes in points of water diversion to account for compliance with in-stream flow standards as part of TRPA permitting procedures. California Department of Fish and Game
and the U.S.D.A. Forest Service,
Lake Tahoe Basin Management Unit monitored Lahontan cutthroat trout (LCT) population numbers and have collaborated on the restocking of a recreational population of LCT into lakes in the Lake Tahoe Region.
The continuation of native wildlife and fish communities is important to the Lake Tahoe Basin. Biological resources provide ecosystem services (e.g., pollination, seed dispersal, pest control), enhance recreational experience (e.g., fishing, wildlife viewing), and can serve as barometers of environmental condition.