Using Genetics to Better Understand Catostomid Reproduction within Large River Systems

Catostomidae, the third largest freshwater fish family, comprises a high percentage of fish biomass in river systems throughout North America. However, there is little information on the reproductive life history for this family in large, Midwestern rivers and their tributaries. To address this, we sampled larval fish in three tributaries of both the Illinois River and Wabash River in conjunction with environmental data on factors thought to be important for reproduction. Between 2016 and 2017, we collected 130 and 2626 catostomid larvae from the Illinois and Wabash River tributaries, respectively. Next Generation Sequencing was used to identify larvae to either genus or species because at this life stage catostomid larvae are morphologically indistinguishable. Results of larvae identification are still pending due to processing time. We expect Wabash River tributaries to have a higher abundance of Moxostoma (Redhorse) while the Illinois River tributaries will have a higher abundance in Ictiobus (Buffalo) due to differences in connectivity between the systems. Logistic regression analyses indicate that Catostomidae larvae presence is dependent on water temperature (°C), water height (ft), and discharge (cfs). Future research will examine the relationship between larval and adult catostomid abundance in the Illinois and Wabash River systems.