Use of various fishing gear for sampling gammarids in the lakes of the Altai territory

In brackish drainage lakes of the Altai Territory, gammarus G. lacustris reach a huge number, dominate ecosystems and serve as a valuable object of industrial fishing. In the absence or oppression of the fish population, gammarids inhabit not only the bottom layer, but also, during the period of open water, are distributed throughout the water column and, due to their high mobility, they avoid traditional sampling tools. It is impossible to forecast the recommended catch of gammarids without accurately taking into account the quantitative characteristics of their populations. The purpose of the work is to choose fishing methods and gear for the most reliable assessment of the quantitative indicators of gammarids in different seasons in the lakes of the Altai Territory. A comparative study of the capture of various fishing gear and methods when taking samples of gammarids in three model lakes of the Altai Territory in 2023–2024 was carried out. As tools and methods in the ice period, the following were used for sampling gammarids: a mormysh trough trap, an ice drill, a benthic bottom grab and a plankton network Jedi. During the open water period, bottom gammarids were caught with the bottom grab, a trap frame with weighting in the form of a frame sliding along the bottom (beam trawl) and without it. In the water column, a Judy net (oblique and vertical catches) and filtering a certain volume of water with a bucket through a plankton net were used to catch gammarids. The results of the research show that the most suitable fishing gear for catching gammarids during the ice period were a mormysh trough and a plankton net; during the open water period — a Judy plankton net and a beam trawl. The advantages and limitations of the selected fishing methods are discussed.