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Yellowstone National Park Report

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Fishery managers are often hampered in population assessment efforts by an inability to accurately age target species. This problem prevents reliable mathematical calculations on the influence of existing or proposed regulations on fish yield and population structure. Such is the case with cutthroat trout in Yellowstone Lake, Yellowstone National Park. Currently the cutthroat trout are aged using scales, but there is substantial inaccuracy in the aging, especially among older fish. The objective of this project is to assess alternative aging structures that may produce more accurate results. Several bony structures have been shown to be superior to scales in the aging of older fish. These structures include otoliths and various fin rays. This project will compare the results of age determinations using scales to the results obtained using other skeletal structures.