Summary

Description

A largescale lake study on Interior Alaska National Wildlife Refuges NWR was undertaken from 19841986. Six NWRs were surveyed Innoko, Kanuti, Koyukuk, Nowitna, Tetlin, and Yukon Flats and lakespecific habitat and fish data were collected from 135 lakes, though a comprehensive report of the findings was never published. This Alaska Fisheries Data Series Report presents these data, allowing public access to this important information. Lake locations, reference and bathymetric maps, lake habitat descriptions, and fisheries data are organized and presented. Lowland lakes were most commonly sampled 74, followed by foothill 31 and oxbow 30 lakes. The highest elevation and deepest sampled lakes were in Tetlin NWR. The highest water quality measurements conductivity, total alkalinity, total hardness, and pH came from Yukon Flats NWR lakes. Of the 135 lakes sampled, 102 lakes contained fish. A total of 15 fish species were collected throughout the study, with Tetlin NWR lakes having the highest species diversity 9 species and Nowitna and Yukon Flats NWRs having the lowest 6 species. Humpback whitefish Coregonus clupeaformis, least cisco C. sardinella, and northern pike Esox lucius had the widest distribution, being present in all six refuges. The highest frequencies of fish occurrence were in oxbow and lowland lakes, lakes with river connections, and lakes with high flood potential. Foothill lakes and lakes without river connections had the lowest probability of fish capture. Koyukuk NWR had the most sampled lakes containing fish 96 and Yukon Flats NWR had the fewest sampled lakes with fish present 49. Northern pike was the most ubiquitous species, occurring in 90 of all lakes containing fish. Fish species diversity was highest in lakes with river connections 14 species.