Movement, Growth, and Production of Brown Trout in Sympatry with Brook Trout in a Southern Appalachian Stream

A 1,532-m reach of Laurel Fork, a second-order tributary of the Doe River, Tennessee, was divided into 37 study sections which were sampled every 3 months by electrofishing. Brown trout (Salmo trutta) and brook trout (Salvelinus fontinalis) were weighed, measured, given a unique mark, and returned to the section from which they were caught. Population estimates were made with the Jolly Seber technique. Movement, density, instantaneous growth rate, biomass, and production were calculated. A large portion of recaptured brown trout (87%) and brook trout (63%) had trimonthly movements <75 m. Small sample sizes precluded calculating growth and production for brook trout. Mean instantaneous growth rates for brown trout were highest in August-October (0.45 and 0.77) followed by February-April (0.41), May-July (0.18), and November-January (0.13). Like growth rate, production was highest in the early fall (3.44 kg^a) followed by early spring (2.48 kg/ha), early summer (2.29 kg/ha), and early winter (0.81 kg/ha). Total annual brown trout production in Laurel Fork was 9.02 kg/ha. The majority of this production (4.16 kg/ha or 46%) was by age 1 fish, though this was not significantly different from age 2 production (3.33 kg/ha or 37%). Older fish, ages 3 and 4 combined (1.06 kg^a or 12%) were not significantly different from age 0 (0.47 kg/ha or 5%). The annual production to biomass ratio (P/B) for brown trout (0.85) was calculated using the mean biomass (10.6 kg/ha) and total annual production (9.02 kg/ha).

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ID
11183