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FEATURES OF BEHAVIOR OF ORDINARY SPRAT (BY RESULTS OF HYDROACOUSTIC RESEARCHES)

Caspian sprats are reserve target species. The study of species identification of Caspian sprats was carried out on board a research ship “Researcher of the Caspian Sea” using EK-60 hydroacoustic complex having stationary antennas with a split beam of 38 and 120 kHz. The behavior and distribution of ordinary sprats in the western part of the Caspian Sea (Middle part of the Caspian Sea off the coast of Dagestan) was investigated. Echo recordings of hydroacoustic surveys made in 2011-2017 covering the water area with depths from 20 to 300 meters were considered. A database with hydroacoustic research files was created, containing the parameters of the surveys and the graphic display of the echograms. Taking into account the negative reaction of ordinary sprat to light, both day and night recordings were considered. Characteristic echoes of ordinary sprat are described in the seasonal aspect. These studies, describing the nature of the behavior of ordinary sprats, are important for the organization of fishing in the western part of the Caspian Sea. It has been stated that density of sprat shoals during spring-summer period is not high, fishing by bottom trawl is efficient only at the end of August. The most promising sprat accumulations can be found in early spring (March) and in October and November, when sprat is caught in the industrial scale. The study results describing special behavior of ordinary sprats can be used in organizing sprat fishing in the Western part of the Caspian Sea.