This study reviews the introduction history and distribution of alien freshwater crayfish in Taiwan through literature surveys, morphological examination of preserved specimens, and field surveys. Since the 1970s, multiple non-native crayfish species have been introduced mainly for ornamental, culinary, and aquaculture purposes, but their status has been poorly documented. The introduction of alien freshwater decapods began in 1970 with large freshwater prawns (Macrobrachium spp.). In the 1980s, the red swamp crayfish, Procambarus clarkii, was introduced and established in the wild. The 1990s saw introductions of the Australian redclaw, Cherax quadricarinatus, and yabby, Cherax destructor, for aquaculture trials. Morphological observations of wild P. clarkii specimens and absence of branchiobdellidan ectosymbionts—typical in Japanese populations—suggest a possible Japanese origin, though alternative explanations exist, warranting genetic confirmation. Field surveys revealed an established population of C. quadricarinatus in the Mudan River system, likely due to escapes from aquaculture and pet releases. Research on alien crayfish in Taiwan is developing, with increasing graduate level studies. This review clarifies their introduction history and distribution, providing fundamental data for fisheries management and invasive species control.
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.
The invasive White River crayfish, Procambarus acutus (Girard, 1852), has recently been reported from several regions of central Ontario, Canada through the online platform, iNaturalist as well as the Invading Species Awareness Program. Between September 2022 and September 2025, we conducted surveys to confirm these reports. Our results show that P. acutus is now established and reproducing in the Severn Sound region where we collected a female with eggs and reports of females carrying young and freelivingyoung of the year have been posted on iNaturalist since. In 2024, a report of suspected P. acutus in Oakbank Pond in Thornhill, Ontario was confirmed by subsequent surveillances resulting in multiple captures from burrows in ditches near the pond, including a female carrying young. Our observations indicate the species is established and surviving in and around the pond and poses a risk of invasion into the headwaters of the Don River, one of the major tributaries to Lake Ontario. Our study confirms the presence and establishment ofP. acutus in the Port Severn region, as well as Oakbank Pond in Thornhill, and expands the distribution ofthis species in Ontario and, as a result, Canada. Copyright (c) 2025 by The Author(s). Published by the International Association ofAstacology. This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
This study documents new aspects of the distribution, ecology, and conservation of the smooth crayfish, Euastacus girurmulayn Coughran, 2005, a dwarf freshwater crayfish endemic to rainforest headwater streams of northeastern New South Wales. Field surveys extended its known distribution from the Wilsons River system to include the Tweed and Brunswick River basins and the Cudgera Creek drainage, increasing the extent of occurrence (EOO) to 200.7 km2 and area of occupancy (AOO) to 60 km2. The species is a habitat specialist confined to shaded, permanently flowing upper catchment streams between 59-718 m in elevation. New records provide the first detailed observations of fecundity, confirm a maximum size of 34.7 mm OCL, and extend its altitudinal range. Molecular analyses validated the distinctiveness of E. girurmulayn and revealed marked divergence among populations, indicating the presence of distinct evolutionary significant units (ESUs). Major threats include climate change, high-intensity bushfires, drought, habitat loss, invasive species, illegal collection, and potential disease introduction. These findings support the recent listing of E. girurmulayn as Endangered under the EPBC Act (criteria B1ab(iii, v)) and highlight the urgent need for targeted conservation actions to ensure the persistence of this highly range-restricted species. Copyright (c) 2025 by The Author(s). Published by the International Association ofAstacology. This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
In this study the reproduction of the southernmost Italian population of the invasive Pacifastacus leniusculus (Dana, 1852) was analyzed. The species was recorded for the first time in the Clitunno River in 2020, an eradication plan started in June 2022 as part of the LIFE IMAGINE 19 IPE/IT/000015 project and aspects of the reproductive biology were examined from individuals captured. In this population, gonad maturation starts in February in females and in May in males. Spawning begins in October and the incubation lasts approximately four-five months. The smallest ovigerous female recorded had a cephalothorax length (CL) of 3.3 cm at an estimate age of 2+. Ovarian eggs and pleopodal eggs number ranged from 142 to 726 and from one to 481, respectively. A positive significant linear correlation between ovarian egg number and female CL was observed. Pleopodal egg diameter was positively correlated with female CL, indicating that bigger females produce larger eggs. This study shows the species is well adapted to the environmental conditions of the new habitat, exhibiting early sexual maturity, and a high potential fecundity but with a high percentage of egg loss. The reproductive characteristics highlighted in this study could help optimize containment efforts for the signal crayfish. Copyright (c) 2025 by The Author(s). Published by the International Association of Astacology This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
