Movement of introduced flathead catfish Pylodictis olivaris in the upper Gila River basin, New Mexico, and potential impacts on native fishes

Authors: Hedden, Skyler*, Gido, Keith

Year: 2015 (xlvii)

Abstract

Understanding movement behavior of nonnative fish predators can help identify potential impacts these organisms are having on native species. We used radio telemetry to observe nonnative flathead catfish, Pylodictis olivaris, at hourly, daily, and seasonal scales from May 2014 to June 2015 in the upper Gila River basin, New Mexico. Movements varied among individuals with a majority moving <150 m from capture location. However, some more mobile fish, moved substantial distances (692-42840 m). Activity and temperature sensors implanted in a subset of fish allowed us to examine fine scale movement of flathead catfish during the course of the study. Activity was greatest in summer and fall with some individuals moving substantial distances downstream to warmer river reaches before the winter. Daily activity was greatest during evening but late afternoon activity was observed in summer and fall. Nightly movements only involved short distances (5 m) and no fish exceeded a single movement >80 m. Managers can use this information to understand potential overlap with native species, target future removal efforts in areas where these fish are concentrated, and avoid stocking native fishes in reaches where flathead catfish tend to aggregate.