Does Crayfish Molting Affect Environmental DNA Detectability?

Abstract We report the first confirmed occurrence of Cambaroides wladiwostokiensis Birstein & Vinogradov, 1934 in China, based on field surveys conducted between 2015 and 2024 in the Upper Morin and Suifun River basins. A total of 78 individuals were collected, and 62 adult specimens were examined in detail. This study presents the first comprehensive morphological description of the species from China, supplementing previous accounts that lacked dissection-based analyses. Diagnostic traits distinguishing C. wladiwostokiensis from sympatric congeners (C. dauricus, C. schrenckii) are clarified. Historical records were critically reassessed, and several misidentifications and ambiguous locality data were corrected. Additionally, our surveys documented local extirpations of C. dauricus and C. similis in parts of northeastern China. Major threats to native populations include habitat degradation, water pollution, and unregulated exploitation. Although C. wladiwostokiensis persists in some protected areas, its longterm survival is threatened by invasive species. This study highlights the urgent need for conservation measures targeting native East Asian crayfish and provides essential morphological and ecological data to support future monitoring and management strategies.