Semester

Fall

Date of Graduation

2007

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Wildlife and Fisheries Resources

Committee Chair

Kyle J Hartman

Abstract

Currently, it is perceived that brook trout (Salvelinus fontinalis ) are experiencing reductions in both range and abundance across their east coast distribution. Data identifying key habitat features influencing growth rates of these fish will be valuable to managers conducting remediation efforts as growth at age has important consequences to survival and fecundity. Of particular importance within Appalachia may be the influence of surficial geology as the mid Appalachian region receives some of the most acidic rain in the nation. Furthermore, endogenous characteristics such as variation in life-history strategy may also influence growth rates of Appalachian brook trout. However, as the quality of growth rate estimates are directly related to the accuracy and precision of aging techniques we first sought to evaluate various aging methodologies (scale, otolith, and fin ray) to determine the technique optimal for brook trout within Appalachia.;Scale and otolith aging techniques produces age estimates of similar accuracy and precision while estimates garnered from fin ray techniques were of reduced accuracy and precision. Scale techniques tended to underestimate fish age within older (age >2) cohorts while otoliths provided the most consistent age estimates across cohorts. Due to the rarity of older individuals within natural populations, scale techniques may be used as a non-lethal alternative to otolith techniques without sacrificing accuracy of age estimates.;Investigations regarding the influence of various habitat characteristic including surficial geologic type indicate pH, brook trout density, elevation, and macroinvertebrate density to influence brook trout growth rates within cohorts 0-2. While geologic type was not found to be significantly influencing brook trout growth, trends in pH among geologic types and the inclusion of pH in stepwise models predicting brook trout growth as a function of habitat features suggest that geology may influence growth rates of these fish. Within an area which receives high amounts of acid precipitation such as the mid-Appalachian region, geologic derived pH may play an important role in determining the upper limit of growth within headwater lotic environments. Actual growth rates may then be a function of secondary mechanisms such as density and elevation.;Within partially migratory fluvial populations of Appalachian brook trout, fluvial individuals tended to maintain significant length and weight advantages within cohorts 1 and 2 over resident individuals. Among older cohorts (3 and 4) the convergence of length measures may indicate the presence of substantial fishing pressure. Growth and condition advantages exhibited among fluvial individuals are most likely a result of increased energy consumption within downstream positions. However, fluvial maturation schedules may also play a role.

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