Hydroacoustic assessment of conditions of spawning migrations of fish on the example of the Prokhladnaya River in the Kaliningrad Region

The paper presents the results of assessing the conditions of spawning migrations of fish in the section of the Prokhladnaya River by conducting hydroacoustic studies of the topography of its bottom. This reservoir is a water body of fishery status of the highest category and ensures the reproduction of anadromous fish species living in the Baltic Sea (salmon, trout, lamprey), as well as important commercial fish species of the Kaliningrad (Vistula) Bay (bream, pike perch, roach, smelt, silver bream, burbot and etc.). The study of morphometric characteristics was carried out using the AsCor software and hardware complex by obtaining spatially distributed depth values in the study area and subsequent construction of a bottom surface model. In the course of the studies carried out, a method for planning a hydroacoustic survey rote on water bodies was developed, a model of the relief of the bottom of this water body was obtained in the form of a regular matrix of depth values, on the basis of which a longitudinal profile of the Prohladnaya River was built. The results of the work made it possible to give a general description of the channel in the study area, as well as to determine the presence of a shoal up to 250 meters long in its mouth part, which has a negative impact on the conditions of spawning migrations of fish.