Density of location of the eastern fresh shrimps (Macrobranchium nipponense De Haan, 1849) in the lower river basin Dnister

Abstract

Purpose.To investigate the distribution of Macrobrachium nipponense in the Dniester river basin in the south of Ukraine. To assess their density and diurnal fluctuations and determine their sex ratios in different waters.Methodology. Shrimps were caught using crayfish traps of original design with a length of 50-200 cm and special submersible wooden boxes of 100x100x100 cm. Depths and bottom relief at the study sites were determined using a Garmin EchoMAP CHIRP 72sv. The location was established using a GPS unit Garmin gpsmap 78s and Google Maps 2D. The sample size was 4687 individuals, 88 locations of shrimp aggragations were detected. The diurnal population dynamics was studied at 7 sites. Sex and sex ratio of sampled shrimps where determined using a standard biological analysis.Findings. The analysis of litertures sources showed the pathways of the spread of M. nipponense across the territory of the republics of the USSR and the history of its acclimatization in the Dniester River. The currents shrimp stock density and their sex ratios in different water bodis of the lower Dniester were determined. The diurnal dynamics of changes in shrimp populations was studied at different sites in the Dniester and Kuchurgan lagoons. It was found that the local populations of shrimp from different waters differ significantly in terms of their numbers and sex ratios. The circadian dynamics of shrimp population density in the Dniester and Kuchurgan lagoons had a similar character but differed in absolute numbers.Originality. The distribution of M. nipponense in the lower reaches of the Dniester was studied for the first time. The abundance of this shrimp in different waters and their sex ratio were established. The circadian dynamics of population changes in the Dniester and Kuchurgan estuaries was studied.Practical value. The results of the study allowed obtaining an objective biological-geographical characteristic of M. nipponense in the conditions of the Lower Dniester basin. The obtained results can be used to assess the state of the natural population of M. nipponense in the lower Dniester and to determine the prospects of its use as an object of domestic fish farming and aquaculture.