Date of Graduation

2006

Document Type

Dissertation/Thesis

Abstract

Large rivers are multidimensional systems where ecological processes occur at a variety of spatial and temporal scales. This investigation addresses the relationship between fish distribution and habitat use within the Marmet Pool of the Kanawha River, West Virginia. Fish habitat use, movement patterns, distribution, and density data were obtained concurrently with abiotic data such as river discharge, temperature, depth, and sediment composition to provide essential dimensions to the assumption that habitat dictates location of organisms. Radio telemetry was used to examine movement, habitat use, and associations between large river fish species. These data were also used to make inferences about the role of main channel and shoreline habitat. In approximately three years, 105 individual fish were tagged representing six species: freshwater drum (Aplodinotus grunniens), common carp (Cyprinus carpio), smallmouth buffalo (Ictiobus bubalus), channel catfish (Ictalurus punctatus), hybrid striped bass (Morone saxatilis X M. chrysops) and flathead catfish ( Pylodictis olivaris). We used displacement of fish as a metric of movement to examine patterns and relationships. Specific fish-habitat interactions considered for analysis were proximity to tributaries, proximity to shore, depth, and substrate character based on average particle size. Periods of high river discharge appeared to limit fish movement, particularly discharge between sampling events. Hydroacoustic data collection provided estimates of fish size structure and density on a seasonal basis, particularly for larval and juvenile fish. The distribution of acoustic targets varied in respect to depth and season, with a significant relationship observed between season and both depth and length of fish. Targets were deepest during the winter and shallowest during the summer. There was no difference in depth between spring and fall. Density data were then compared by season, depth, and length distributions, and a significant relationship was detected between transformed density of targets and season. The highest transformed densities occurred during summer (3.92 targets/cell) and the lowest densities occurred during the fall (5.59 targets/cell). A significant relationship exists between transformed density and length of targets across all seasons. The cumulative density of larval sized targets was greatest, while the densities of small and medium targets were the lowest. A probabilistic model of fish occurrence based on habitat variables deemed important to fish distributions were also constructed. Radio telemetry data were used as the fish occurrence data. The relative contribution and the degree of conditional independence between habitat layers were statistically evaluated, allowing the researcher to make inferences about where fish should occur based on the available data. Distribution patterns were compared between seasons, and a difference in use at the seasonal level were detected. Seasonal differences in distribution patterns were described graphically. The results of the probabilistic model indicate that there are several discrete regions with a high probability (80–100%) of fish occurrence. The majority of the Marmet Pool of the Kanawha River consists of habitat that has a 40–60% probability of occurrence for the tagged species. The results of this analysis provide a visual representation of the probability of occurrence that are easily interpreted by managers and researchers alike. Predicting occurrence of rare species may also be possible with this approach.

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