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Larval fish abundance and habitat associations in backwaters and main channel borders of the Kanawha RiverScott, Mark Thomas 21 November 2012 (has links)
Larval fish distributions were determined in the lower Winfield Pool, Kanawha River, West 85, Virginia, using a 0.5-m plankton net and a 1-m<sup>2</sup> dropbox. Five habitats were sampled with the plankton net, 3 habitats with the dropbox. The 5 deep water water habitats, greater than 1.5-m in depth, sampled by the plankton net included surface tows in Bill's Creek backwater, main channel border upstream and downstream of Little Guano backwater, and Little Guano Creek backwater, where deep tows (1.5 m deep) were also taken. The 3 shallow water habitats, less than 1 m in depth, sampled by the dropbox included open water over silt substrate, open water over a sand substrate, and emergent vegetation. <i>Lepomis</i> species, emerald shiners (<i>Notropis atherinoides</i>), and gizzard shad (<i>Dorosoma cepedianum</i>) were the dominant taxa. The emerald shiner taxa could also have included some larvae of <i>Notropis</i> species which are also present in the Kanawha River but whose larvae have not been described. Overall, the mean total larval density did not differ between the backwater or the main channel borders but the species associated with each habitat differed greatly.
The <i>Lepomis</i> larvae were found predominantly in backwater areas. These areas provide suitable spawning sites for many centrarchids of this river. Upon leaving the nest, the <i>Lepomis</i> larvae moved into the deeper open water areas within the backwater. After reaching the juvenile stage, these same larvae returned to the shallow water habitats where they inhabited vegetated areas. Emerald shiner larvae, while present in both backwater and main channel habitats, were most abundant in the main channel borders. This is probably a result of their parent's pelagic spawning strategy. In all habitats, emerald shiner larvae predominated in the upper 1 m of water. Upon becoming larger, the emerald shiner larvae appeared in the backwaters. This increase in numbers could be due to movement, differential mortality, or higher growth rates. Other cyprinids (excluding emerald shiners and carp) were equally abundant in both backwater and main channel areas. These other cyprinid larvae were also distributed equally, Gizzard shad larvae were found predominantly in the main channel borders. Presumably, these higher densities were the result of main channel spawning. The gizzard shad larvae present in the backwater areas were distributed evenly throughout the water column. Overall, the backwaters were important for the nest-building species found in the river and also for the larger larvae of the pelagic species, and thus acts as a nursery area for these species. Therefore, the backwaters do seem to be important for the fishery of the Kanawha River. / Master of Science
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Distribution of larval fishes in the Winfield Pool, Kanawha River, and direct impacts of commercial navigation traffic on larval fish survivalOdom, Michael Cooper 20 November 2012 (has links)
Distributions of larval fishes in the Winfield Pool, Kanawha River, West Virginia, were determined by sampling two sites with bongo and push nets. Cyprinids, clupeids, and <i>Aplodinotus grunniens</i> dominated collections. Main channel densities were a fraction of the densities along the shoreline, indicating the importance of the shoreline as a nursery. Diel trends in abundance were evident for several taxa, but were likely caused by diel changes in gear avoidance and distribution of larvae. Vertical trends in abundance were apparent for several taxa at the deeper and more lentic sampling site (lower pool). <i>Aplodinotus grunniens</i> were generally more abundant near the bottom, especially during daylight. Cyprinids were more abundant near the bottom in mid-June, but displayed no vertical trends on other sampling dates. Clupeids were more abundant at middepth or surface during daylight, while equally dispersed or near the bottom at night. Vertical trends were not evident at the shallower and more lotic site (upper pool) except for <i>Aplodinotus grunniens</i>, which displayed the same preference for the bottom, as at the lower site. / Master of Science
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