Spatiotemporal Dynamics of Fish in Lake Pskov

The interannual and intraseasonal patterns of the spatiotemporal dynamics of the main commercial fishes from Lake Pskov, one of the most productive water bodies in northwestern Russia, are studied. The results of cartographic analysis of the summer–fall fish distributions in the lake are presented. The results of trawl surveys conducted in years that differed by the water level (2003, 2006, and 2008) were used as the input data. The initial data were aggregated into tables of attributes containing information on the trawling dates, trajectories, duration, average speed, water temperature, and the species and size composition of the catch. These tables were used to map the spatial distribution of seven fish species (bream, pikeperch, roach, perch, white bream, burbot, and ruff). Cartographic estimates of abundance are obtained for roach, pikeperch, bream, pike, and perch. An attempt is made to assess the reproduction efficiency of several fish species (pikeperch, perch, and pike) based on an analysis of their abundance variation from spring to autumn. Maps of the spatial distribution of the pikeperch that account for the size composition of the population are created. The discrepancy in the localization of different age groups in different seasons, along with their moving patterns, is ascertained. The patterns in the fish spatiotemporal dynamics are matched with the available hydrological characteristics.