Landscape-scale factors affecting detection and occurrence of threatened Yaqui Catfish in the Yaqui River Basin, Mexico

Abstract

Desert fishes are some of the most threatened species in the world because of anthropogenic alterations and competition for limited freshwater. Among threatened desert fishes is the Yaqui Catfish, Ictalurus pricei, which is native to southwest United States and northwestern Mexico. Yaqui Catfish populations are declining due to anthropogenic alterations, habitat degradation, fragmentation, and species introductions. Non-native Channel Catfish I. punctatus, pose a significant threat because they can hybridize with native Yaqui Catfish endangering its genetic integrity in the Yaqui River basin. Little else is known about Yaqui Catfish, so we sought to determine what factors were affecting its distribution in the Yaqui River basin. Understanding a species' distribution is critical in taking conservation action, as well defining its habitat and environmental associations. I used MaxEnt to create a species distribution model to estimate the potential distribution of Yaqui Catfish. My findings showed the most important variables in determining distribution were size of stream The MaxEnt model was based off of historical data collected no later than 2005, to understand current distribution, I collected current data and further examined how interactions of Channel Catfish were affecting occupancy, I sampled environmental DNA (eDNA) and habitat covariates in the Yaqui River basin. I used those results in a hierarchal Bayesian occupancy model, that allowed me to determine important variables associated with Yaqui Catfish occupancy and detection probability. I found that interactions with Channel Catfish had a substantial effect on both Yaqui Catfish occupancy and detection.