Evaluating the Effects of Drought and Anthropogenic Alterations on the Growth of Stream Fishes on the Edwards Plateau, Central Texas

Drought and landscape-level anthropogenic impacts, such as alterations of stream channel morphology and flow regime, have the potential to affect fish growth. However, it is unclear how these factors interact. We evaluated the influence of the interaction between drought and anthropogenic factors on growth rates of stream fishes within a pair of adjacent river systems in Texas. The flow regime of the North Llano River (NLR) was heavily altered compared to the South Llano River (SLR) due to stronger spring contributions to base flows. Otoliths from eleven species common to the NLR and SLR were back calculated for estimated lengths at age. Growth data using several models will 1) identify potential differences between the NLR and SLR and their individual species, and 2) if an overall difference is present among individual species we will test for differences between several covariates that vary across specimens. Preliminary results evaluating the effects of drought and altered flow regime on the growth of eleven species will be presented.  Results from this study will provide biologists with an understanding of how drought coupled with anthropogenic alterations affects overall growth rate of stream fishes improving decisions for management and conservation of fishes occupying similar river systems.