Can intensive trapping to reduce the abundance of an invasive crayfish benefit an imperiled congener?

Abstract

Abstract Management aimed at reducing the population sizes of established invasive species can be beneficial for the conservation of native species. Crayfish are some of the most widespread and impactful invasive species in freshwater ecosystems. This study evaluated the efficacy of intensive baited trapping as a tool to reduce the abundance of an invasive crayfish (Procambarus spiculifer) in small streams and benefit an imperiled congener (Procambarus pictus). The invasive crayfish was captured and removed from a 1‐km stream reach through three rounds of intensive trapping conducted over a 16‐month period. The abundance of the invasive species declined significantly in the trapping reach after the initial round of trapping. Throughout the year following the onset of trapping, its abundance within the trapping reach was less than half of that at control sites. The sex ratio of invasive crayfish collected in traps was approximately 1:1, and 31% of captured individuals were likely to be immature based on size class. The abundance of the imperiled species did not change significantly over the study period, but 1 year may not be long enough to detect a response. Overall, the data suggest that periodic intensive trapping can effectively reduce the abundance of this invasive crayfish in small streams, and the extent to which this benefits the imperiled species remains an open question. Future research examining how trapping can best be applied to achieve lasting effects (including trap type, season and barriers to immigration) would be valuable for understanding the conservation potential of this management technique.