Crayfish in central and southern Ukraine with special focus on populations of indigenous crayfish Astacus pachypus (Rathke, 1837) and their conservation needs

Abstract

1. The thick-clawed crayfish (Astacus pachypus Rathke, 1837) is the least studied indigenous crayfish species in Europe. Information about its distribution and biology is out of date by more than 15 years.2. This study identified 94 localities with potential occurrence of thick-clawed crayfish in eight southern and central regions of Ukraine, using questionnaire and literature analysis. Based on the information obtained, a field survey was conducted to examine and confirm the current distribution and abundance of crayfish species and evaluate basic water quality and habitat characteristics in each locality.3. Details of density, sex ratio in the catches, health and moulting condition, threat level and water quality were identified for each population of A. pachypus. 4. Only four populations of this species were found, in lower parts of the Dnieper River, cooccurring with Astacus leptodactylus Eschscholtz, in Kakhovka reservoir near Vesele village, two sites on the Dnieper River near Nova Kakhovka town and near Prydniprovske village, and one locality on the Dnieper's tributarythe Ingulec River near Sadove village. 5. Populations of thick-clawed crayfish at three sites had low crayfish densities of 0.3-0.4 crayfish m −2 or catch efficiency 0.2 crayfish per trap night. Only one locality on the Dnieper River, close to Nova Khakovka, had a stronger population with higher density (1.7 crayfish m −2 ).6. Healthy thick-clawed crayfish inhabit larger water bodies with stable environments and good water quality. Female catch per unit effort was lower, and they had a higher percentage of chelae injuries compared with males. 7. All of the identified thick-clawed crayfish populations are exploited by uncontrolled fishing for consumption and there is an urgent need for conservation of both the crayfish and their habitat.

Integrating fishing and conservation in a risk framework: A stochastic population model to guide the proactive management of a threatened freshwater crayfish

“…In addition to assessing growth rates, stochastic analysis of the lowland Murray region model showed that increasing variation in the distributions of parameters leads to lower expected minimum population sizes. This highlights that E. armatus populations may be susceptible to highly variable environments (not to be confused with highly variable flows), such as the frequency of disturbance from hypoxic blackwater events, and that ensuring the right kind of environment, such as variable flows and good water quality, may be critical for population persistence (Meyer, Gimpel, & Brandl, ; Policar et al, ).…”

Legal Framework for Pontocaspian Biodiversity Conservation in the Danube Delta (Romania and Ukraine)

“…We accounted for taxonomic synonymy and misidentification by selecting both currently accepted and synonymous genus names, which have been used by different authors in the last decade. In total we retrieved 70 invertebrate genus names belonging to mollusks-gastropods and bivalves (Wesselingh et al, 2019); crustaceans-amphipods, cumaceans, copepods (Monchenko, 2003) and decapods (Policar et al, 2018); mysidae (Audzijonyte et al, 2008); cnidaria and hirudinea (Mordukhay-Boltovskoy, 1960). Finally, we also checked the two genus names of sturgeons (Acipenser and Huso).…”

“…29 of January 19, 2021 on approval of lists of species of animals listed in RDBU and species of animals excluded from RDBU). The new list included an endangered crayfish Astacus pachypus (Bláha et al, 2017;Policar et al, 2018) and a gastropod Clathrocaspia knipowitchii, which were absent from RDBU before. At the same time, species that expanded outside their native range were excluded from the list, for example, Hemimysis anomala and Gmelina pusilla Sars, 1896.…”

Genetic diversity, phylogenetic position and morphometric analysis of Astacus colchicus (Decapoda, Astacidae): a new insight into Eastern European crayfish fauna

“…Another east Ponto‐Caspian crayfish thick‐clawed crayfish Pontastacus pachypus Rathke, 1837, is also known from southern slopes of the eastern Great Caucasus (Azerbaijan) and was suggested to occur in Georgia though it has never been recorded there (Derzhavin 1951) or having disappeared as in most of area of its occurrence in Ukraine (Policar et al . 2018).…”