Influence of stream discharge on reproductive success of a prairie stream fish assemblage

We studied the relationship between stream discharge and reproductive success for five members of a prairie stream fish assemblage. Based on information obtained from the literature, we constructed seven models relating stream discharge to successful reproduction. To assess the utility of our models, we collected larval and juvenile Arkansas River shiners Notropis girardi, peppered chub Macrhybopsis tetranema, plains minnow Hybognathus placitus, flathead chub Platygobio gracilis, and red shiners Cyprinella lutrensis from the Canadian River, Texas, during 2000-2001. We removed otoliths and counted daily growth increments to determine ages. Models were parameterized by use of age and discharge data. Models were evaluated with the Akaike information criterion likelihood statistic to assess which model(s) best described reproductive success for each species. Of the seven models evaluated, the best overall model predicted that reproductive success was uniform across dates when discharge was present in the river; however, reproduction was predicted to be unsuccessful during periods when the river was confined to isolated pools. These results suggest that the presence of discharge in the river may be more important for successful reproduction of prairie stream cyprinids than the magnitude of discharge.