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Dynamics and structure of the herring (Alosa immaculata) catches in the Dniester estuary during the 1994?2016 years

Journal: Fisheries Science of Ukraine (Vol.38, No. 4)

Publication Date:

Authors : ;

Page : 52-63

Keywords : Dniester; Dniester estuary; herring (Alosa immaculata); catch dynamics;

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Purpose. To assess the current state of the Pontic shed in the Dniester estuary. Methodology. Ichthyological samples has been collected in the Dniester estuary according to standard methods. Fish has been caught using gill nets with 30?32 mm mesh size. The methodical guidelines "Metodiki zboru і obrobki іhtіologіchnih і gіdrobіologіchnih materіalіv z metoju viznachennja lіmіtіv promislovogo viluchennja rib z velikih vodoshovishh і limanіv Ukrayiny" (Кyiv, 1998) and "Metodicheskie ukazanija po ocenke chislennosti ryb v presnovodnyh vodoemah" (Moskva, 1990) were used for fish stock assessment. The dynamics of water discharge in the Dniester River was presented based on the observations at gauging stations in Bendery and Tiraspol. Findings. The data of catch dynamics, age and sex composition, length-weight characteristics of the Pontic shed Alosa immaculata Bennett, 1835 in the Dniester estuary 1994?2016 have been presented in the paper. According to official statistics data, the annual catch of the Pontic shed in the Dniester River and Dniester estuary in 1996?2016 ranged from 1.3 to 62.0 tons, with an average of 24.6 tons ? 9.8% of the total catch of the Pontic shed in the Danube-Dniester interfluves. A dependence of catch amounts on the water regime of the Dniester River has been observed. An increase in the water flow rate in the river during the spring flood in full-flowing years (annual flow of more than 10 km3), contributes to an increase in the Pontic shed catch in the Dniester estuary. Currently, catches are dominated by age-3 (40.5?59.2% of the total catch) and age-4 (30.7?42.0%) fish. Older age groups are not numerous. Sex ratio was unequal. Females predominated in the control catches, accounting for 65.4% of the total catch. The stock of the Pontic shed entering the Dniester estuary in 2016 was estimated to be 221.0 tones. We recommended to extend the ban of the specialized Pontic shed fishing during the spawning period. Originality. The current state of the spawning stock of the Pontic shed population in the Dniester estuary is presented. Practical value. It is recommended to change the timing of the ban on the specialized Pontic shed fishing in the Dniester estuary, to ensure the passage of a greater number of individuals to the spawning grounds.

Last modified: 2017-01-31 02:30:22