Fish Ages and Ecology from Lakes in Glacier National Park. Final Report to Glacier National Park
Stafford C. 2014. Fish Ages and Ecology from Lakes in Glacier National Park. Final Report to Glacier National Park. College of Forestry and Conservation, University of Montana. Missoula, MT
Four fish populations from Glacier National Park were aged to support ongoing research and monitoring. These populations were: Cosley Lake lake trout, Hidden Lake Yellowstone cutthroat trout, Logging Lake westslope cutthroat trout, and Sherburne Reservoir northern pike. These populations previously were sampled as part of a survey of mercury contamination in park waters, making fish ages useful to help assess the causes of any future changes in fish mercury levels. Further, all four populations are utilized by anglers and have additional aspects which make them of conservation interest. The project was focused on lake trout from Cosley Lake where additional investigations were made. The life history and morphology results from these fish show that two varieties were present: regular lake trout (leans) and a dwarf variety resembling humpers. Gill net and 13C data show that the dwarf lake trout occurred mostly in deeper waters while the leans ranged widely in depth but generally occurred in shallower waters than the dwarfs. 15N values are consistent with invertebrate and fish diets in the dwarfs and leans, respectively. The presence of dwarf lake trout in park waters is of considerable scientific and conservation interest as humpers are rare and have never been observed in such a small lake. The presence of two varieties in Cosley Lake also may have relevance in terms of their differing vulnerabilities to angler harvest. Other findings include that northern pike from Sherburne Reservoir may have irregular recruitment, and that the Hidden Lake cutthroat trout grew more slowly and matured at a later age than those from Logging Lake.
- Type
- Unpublished Report
- Authors
- Stafford, Craig
- Date of Issue
- 2014-02-10
- Publisher
- College of Forestry and Conservation, University of Montana
- Units
- GLAC
- Keywords
- Aquatic Studies, Fish, Fisheries, Lake Trout, Monitoring, Population Dynamics, Westslope cutthroat trout
- Subjects
- Ecological Framework: Biological Integrity | Focal Species or Communities | Fishes