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Tuesday, January 30 • 9:20am - 9:40am
RIVERS & OXBOWS: Capture Efficiency of a Fine-mesh Seine in a Large River: Implications for Abundance, Richness, and Diversity Analyses

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AUTHORS. Kevin Kapuscinski, Lake Superior State University; Derek Crane, Coastal Carolina University

ABSTRACT. Fishes in shallow water are often sampled by seining, but studies rarely include corrections based on varied capture efficiencies (CEs) for species or size classes, or account for false negative errors of detection. We sampled fishes in shallow, nearshore areas of a large river using a fine-mesh seine within a blocknet and (1) estimated CEs for age-0 and yearling-and-older (YAO) fishes and made comparisons among species (within age groups), (2) determined if CEs were affected by water depth and aquatic vegetation cover, (3) estimated the proportions of sites that individuals were present but not detected for each species, (4) compared estimated taxa richness and Shannon diversity index values to true values, and (5) determined if richness estimates were affected by depth and aquatic vegetation cover. We found that (1) CEs of age-0 fishes were not affected by depth, but did differ among four levels of vegetation cover and these relationships differed among species, (2) CEs differed among YAO species (range of species-specific means=0.17-0.93), but were not affected by depth or vegetation cover, (3) total abundance of age-0 and YAO fishes (summed across species) captured during the first seine haul were highly correlated with true abundance (r = 0.96) but underestimated, (4) proportions of false negative errors of detection were typically higher for YAO than age-0 fishes, and (5) estimated taxa richness and Shannon diversity were correlated with true values, but generally underestimated. Numerous biotic and abiotic factors appear to drive wide variations in CEs and false negative errors of detection among species, so results from any one study are likely only applicable to particular species occupying similar habitat types. Additional research is needed to elucidate these relationships, given potential effects on interpretation of survey results, presence/absence modeling, and resulting management actions.

Tuesday January 30, 2018 9:20am - 9:40am CST