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Movement, growth and mortality of brook trout within the Hazel River, Shenandoah National Park
Bryan, Roger D.
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Density and standing stock of brook trout within the Hazel River, Shenandoah National Park, declined sharply between 1982 and 1989. Most of the reduction occurred within the middle and lower reaches, where density of brook trout declined 66% and 920/0, respectively. This study characterized the movement, growth, and mortality of the Hazel River brook trout population in 1989-1990 and examined the role of these phenomena in the recovery of that population. Physical habitat appeared excellent throughout the stream, with adequate pools, cover, and spawning substrate in all sections. Results from visible implant tag recoveries established that the majority (60%) of adult and yearling trout were sedentary during the one year study period. Brook trout exhibiting movement tended to move upstream during the fall over relatively short distances ( < 250 m). Movements of up to 700 m (up- and downstream) were observed in less than 5% of post-juvenile trout. Young-of-the-year (YOY) trout moved more frequently than other age groups and tended to move downstream; they are probably the primary vehicle of downstream recolonization. Growth and condition of Hazel River brook trout were typical of other streams within Shenandoah National Park. Poor growth occurred during the summer months, which is typical of southeast stream trout populations. Generally, growth was higher in areas where density was lowest. Estimated mortality over summer was highest (400/0) for yearling and adult trout within the upper reaches. Despite closure of the Hazel River to angling for two years, its brook trout population remained depressed in 1989. The study demonstrated that recovery of depleted trout stocks through intrastream migration may be slow. Reasons for the continued depression of the brook trout population in the Hazel River may include predation by American eels, illegal angIer harvest, the sedentary nature of stream-dwelling trout, or a combination of these factors
- Masters Theses