Morphological features of the Oriental river prawn (Мacrobrachium nipponense (de Haan, 1849)) at different localities in Ukraine

The Oriental river prawn (Macrobrachium nipponense) is an East Asian decapod, recently recorded as invasive in Europe.Here, we describe key morphological and morphometric features (sex, total length and weight, lengths of both 2 nd pereiopods and number of dorsal and ventral rostrum spines) for distinguishing populations in different waterbody types in Ukraine (one brackish and two freshwater).Over the year, males tended to slightly dominate e with a mean catch of 54.79%.Females became more prevalent in catches during the June-October spawning period when ovigerous individuals were recorded, a pattern that differed from both tropical and temperate parts of its native range.We recorded no significant difference in linear growth characteristics between the invasive prawns and native populations, and both sexes displayed a stable mass-length correlation with isometric growth characteristics typical of the species.Our results indicated that dentition number (dorsal and ventral) was the most stable morphological feature, while the other parameters examined could be used for both population tagging and observation of seasonal changes.In Ukraine, female prawn size was greater in freshwaters than brackish waters, opposite to the trends observed in its native range.The larger size and growth rate of prawns in the Danube delta suggests that brackish water bodies in Ukraine have a relatively low potential for fisheries and prawn farming.