Variation in CPUE, Diet, and Parasite Prevalence Among Fishes in the Brazos River Across Drought and Non-Drought Years, with Emphasis on Red Shiner Cyprinella Lutrensis

We collected fish and macroinvertebrates samples during drought and non-drought years in spring-summer 2010, 2011, and 2012 in the lower Brazos River near College Station TX. We seined to calculate fish CPUE and diets for each hydraulic habitat. We calculated frequency of occurrence (%O), absolute and proportional volume and prey specific abundance (index describing feeding strategies and niche width of predators). In 2011 and 2012 fish with intestinal parasites were recorded for each seine haul and prevalence of infection was calculated.  Diets of approximately 30 fish were sub-sampled from preserved fish > 30 mm TL. We calculated the percent of fish with food each year for each habitat.  Redundancy Analysis and variance decomposition showed that diet composition for Red Shiner was uniquely related to habitat type (26%) and year (35%). During the drought of 2011, as compared to 2010 and 2012, we noted greater total fish CPUE, parasite prevalence, and % empty stomachs, and decreased relative abundance of benthic macroinvertebrates; whereas the diet of Red Shiner showed fewer number and different types of dominant taxa, and greater diet specialization among individuals.  Results suggest that as resources decreased, generalists partitioned resources by specializing on different prey.