Tributary use and movement in the San Juan River fish community

Authors: C. Nathan Cathcart, Keith B. Gido, Mark C. McKinstry

Year: 2012 (xliv)

Abstract

Fishes often require diverse habitats throughout their lives, and those habitats are often distributed throughout a stream network. Accordingly, fulfillment of different life stages will involve movement among those habitats. Using a riverscape study design, we identified abundance and dispersal of fishes across broad spatial scales, with a focus on tributary confluences. Within riverscapes, confluence zones often serve as areas of more frequent exchange between habitats that differ in their abilities to fulfill specific life history attributes of species. To identify movement patterns and quantify tributary use of the San Juan River fishes, we tagged all fishes >115 mm with passive integrated transponder (PIT) tags in tributary stream and mainstem San Juan River sites in 2012. Fish detections relied on three stationary PIT antenna arrays in the McElmo Creek system complimented by four mobile PIT antennas used at strategic locations of McElmo Creek, Yellow Jacket Creek, Chaco Wash, and the San Juan River. We found tributary confluences were used frequently by endangered species, and their movements into these habitats coincided with increasing discharge, and potential seasonal patterns of habitat use. These results suggest tributary habitats are potentially important for multiple life stages of endangered species but also may provide refugia for nonnative channel catfish, Ictalurus punctatus. Future objectives will be to identify ecological correlates to movement patterns of fishes.