Reference |
Rooper, C.N., M.D. Bryant, and S.J. McCurdy. 2000. Use of scales to assess summer growth of resident cutthroat trout in Margarite Lake, Alaska. North American Journal of Fisheries Management 20:467-480. |
Abstract |
The opening of a fish ladder in 1990 enabled migration of anadromous fishes into Margaret Lake, Alaska, dramatically changing the environment for its resident cutthroat trout Oncorhynchus clarki. Cutthroat trout summer growth was inferred from scales collected in the fall from 1989 to 1997 by measuring the distance between the scale edge and the last annuli. Bias in scale aging was estimated at less than 0.5 years for cutthroat trout scales, and precision (the coefficient of variation of multiple agings of the same scale) was estimated at 10%. Distances between adjacent annuli were not significantly different when multiple scales were measured from the same fish. When scale distances were extrapolated into body length growth, summer growth rates ranged from 0.44 to 1.09 mm/d. Summer scale growth for age-2 fish was significantly higher than at ages 3–5, and these four age-classes did not exhibit the same growth pattern over the years of the study. Summer scale growth, highest in 1996 and 1997, the final 2 years of the study, was correlated to both air temperature and the estimated abundance of cutthroat trout. |
Tag |
VI Alpha |
Objective |
Verification of aging methods |
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