Ecology of kokanee salmon and rainbow trout in Crater Lake
Buktenica M and Larson GL. 1990. Ecology of kokanee salmon and rainbow trout in Crater Lake. Pages 185-195. In Drake ET, Larson GL, Dymond J, Collier R (ed): Crater Lake: An ecosystem study. Corvallis, Oregon. June 18-22, 1988. San Francisco. 69th Annual Meeting of the Pacific Division/American Association for the Advancement of Science
"Crater Lake, originally barren of fish, was stocked on an irregular basis from 1888 through 1941 with several species of salmonids. Two species occur in the lake today – kokanee (Oncorhynchus nerka) and rainbow trout (Salmo gairdneri). Thus study was initiated in the summer of 1986 to evaluate the ecology of adult fish in terms of length, weight, age, growth, morphology, food habitats, and distribution in Crater Lake relative to the lake’s limnological characteristics. Age determinations from scale analysis, supported by modal progressions in length-frequency histograms, indicated that the kokanee salmon population was dominated, in number, by the 1984 year class. The rainbow trout population was composed of multiple age groups. Food sources were partitioned in that kokanee salmon generally fed on small-bodied taxa (mean dry weight 1.3 mg) from midwater column and from lake bottom; rainbow trout fed on large-bodied taxa (mean dry weight 9.8 mg) from the lake surface and the lake bottom. Hydroacoustic studies during the first week of September 1987 showed that the fish underwent diel migrations within and between the nearshore (0 m to 100 m contour) zones and offshore (100 m to 589 m contour) zones of the lake. Based on capture records, it appeared that kokanee were primarily offshore and in deep water during the day, and then they moved shoreward into shallower water at night. Rainbow trout appeared to remain nearshore in shallower water during the day than at night. The maximum depth for an acoustic target was 98.5 m. The maximum depth capture for kokanee in Crater Lake was 86.25 m. The ecology of these two species is a dynamic response to Crater Lake’s limnologic variables. Trophic interactions suggest that this is not a simple benthic-rainbow trout and limnetic-kokanee salmon system. A complex series of interactions are catalyzed by these species operating within and between limnetic and benthic communities."
- Type
- Conference Proceeding Paper
- Authors
- Buktenica, Mark; Larson, Gary
- Units
- CRLA
- Keywords
- Abundance (Biodiversity), Age Distribution, Animal Studies, Aquatic Ecology, Aquatic Studies, Distribution, Distribution (Biodiversity), Ecology, Fish, Fish Ecology, Food, kokanee salmon (Oncorhynchus nerka), Limnology, Observations, Presence (Biodiversity), Rainbow Trout (Salmo gairdneri), Weight