Influence of Accidentally Introduced Fish Species on the Biodiversity of Ichthyofauna of Reservoirs in the Upper Reaches of the Syrdarya River Basin

During the latter part of the previous century, efforts were made to introduce and cultivate several economically valuable fish species in fish ponds, with the aim of enhancing the diversity of valuable fish in the reservoirs of Uzbekistan. In addition to the intentional introduction of fish species, some non-commercial and commercial fish species were inadvertently introduced. As a result, some of these species adapted to the new environment, integrated into the local fish population, and displayed invasive behavior, leading to competition with native species. Upon entering new habitats, numerous invasive fish species were able to reproduce naturally, giving rise to fertile offspring. These processes negatively affected the local ichthyofauna. In some extreme cases, the adverse effects of invasive fish species are evident through their competition with native species for essential resources for life. The article analyzes the consequences of the introduction and naturalization of invasive fish species and their impact on the biodiversity of the ichthyofauna of reservoirs in the upper reaches of the Syrdarya river basin, which were accidentally introduced into the reservoirs of Uzbekistan. The morphometric indicators, the linear logarithmic indicator between body weight and length, the reproductive ability of females, as well as the linear growth over the years of life of invasive fish species from the basin of the upper reaches of the Syrdarya river were determined.