Status, Distribution, and Conservation of Native Freshwater Fishes of Western North America

Population Status and Trends of Four Bear Lake Endemic Fishes

Scott A. Tolentino

doi: https://doi.org/10.47886/9781888569896.ch7

ABSTRACT Populations of the four Bear Lake endemic species, Bonneville cisco Prosopium gemmifer, Bonneville whitefish P. spilonotus, Bear Lake whitefish P. abyssicola, and Bear Lake sculpin Cottus extensus, were monitored by Utah Division of Wildlife Resources and/or Utah State University. Bonneville cisco populations have been monitored annually since 1990 using hydroacoustic sampling. The population has ranged from 1.9 to 9.7 million fish. Because no reliable method was available to determine whitefish species identification prior to 1999, the whitefish population was monitored from 1973 to 1998 by lumping the catches of both species and referring to them as the “whitefish complex.” In 1999, the Utah Division of Wildlife Resources began recording the percentage of gill-net catch comprised by Bonneville and Bear Lake whitefish. Bonneville whitefish comprised between 84% and 94% of the gill-net catch while Bear Lake whitefish comprised between 6% and 16%. Relative abundance of Bear Lake sculpin was monitored biennially since 1998 using catch rates from bottom trawling. Average catch per 20-min trawl at both the top and bottom of the thermocline at three different sites ranged from 37 fish to 79 fish.