The method’ features for assessing the number of fish in small reservoirs and watercourses using an underwater video camera

Background. Traditionally, ichthyological studies were carried out on large reservoirs and rivers with developed fishing, using the constantly improving methodology for assessing the fish number. In the 21st century, there has been a practical interest in small reservoirs and watercourses. This is due to the massive transfer of water bodies and their hydraulic structures for use and the need to assess the damage caused to aquatic biological resources of watercourses and water bodies under any negative impact with the development of compensatory measures. However, the set of existing methods for studying the abundance of ichthyofauna in them is quite limited, applicable in small areas of water areas, and requires a complex registration of a special permit for catching aquatic biological resources. Our proposed modern method for assessing the abundance and species diversity of fish using an underwater video camera in small water bodies makes it possible to significantly simplify and improve the quality of research and is accessible to any researcher of ichthyofauna. At the same time, quite naturally, researchers have a number of questions about its practical application. The purpose of the publication is to highlight some of the features of using this technique, taking into account the accumulated material and testing experience. Materials and methods. The research was carried out by a system of underwayter video surveillance Calypso FDV-1111 according to the developed method. The survey was carried out on the control areas of the investigated water body, fish were taken into account, once marked by the camera. The results of approbation of the method in the Penza region on the Sanderka lake, the Lesnoy pond, the peat quarry, the section of the Staraya Sura and Sura rivers are presented. Results. Research with an underwater video camera to determine The number of fish is effective in small water bodies of central Russia, characterized by low transparency and low concentrations of fish. It is advisable to use direct counting of once encountered fish with conversion per unit area – ind./m2 and then – per g/m2. The highest occurrence of fish was noted in a fairly productive lake Sanderka with a wide species composition of ichthyofauna and a large number of juveniles. A significant amount of fish was recorded in the peat quarry due to the large percentage of juveniles. According to the main demanded indicator – the ichthyomass of the reservoir due to large fish in the section of the river Surah. Compared to the results obtained by other accounting methods in small water bodies, biomass data are high, especially in rivers. In contrast to non-aquatic catches with a predominance of juveniles and small fish, when working with the camera, more large individuals are recorded that are in places inaccessible for fishing and avoid it. The results obtained by this method are quite adequate to the existing requests for fish productivity presented to small water bodies with their scanty fish stock. This method of accounting is both an alternative and a good addition to the complex use of traditional methods of accounting for the number of fish in small water bodies of central Russia. Conclusions. Along with actively practiced video surveillance methods registration of terrestrial animals, obviously, and in the field of assessing the number of fish, the time has come to use underwater video cameras. Taking into account the availability of the method, costeffectiveness, without the death of the studied objects in the study of aquatic biological resources, the study of small reservoirs and rivers of their fish population is intensified. And comprehensive research in combination with other methods will provide comprehensive information on the state of aquatic biological resources of small reservoirs and rivers