The state of study of parasites and symbionts of crayfish

Abstract

The article analyzes the available literary sources that highlight the issue of studying parasites and symbionts of crayfish in the reservoirs of Ukraine and Europe. Crayfish (of the genus Astacus) are an integral part of the Dnieper-Buzka estuary. These are the only edible invertebrates in the freshwater reservoirs of the region. High taste qualities put them in the category of delicacies and determine a stable demand on the world market. Until the middle of the 20th century, crayfish were a traditional object of fishing in the reservoirs of Europe. It was concluded that high taste qualities put them in the category of delicacies and determine a stable demand on the world market, but currently many industrial areas have lost their importance due to a significant decrease in the number of these hydrobionts for various reasons. Crayfish are unstable species, and their numbers can change dramatically over time. For this reason, studies aimed at identifying the factors that determine the dynamics of the number of crayfish in reservoirs, especially under the influence of diseases of various etiologies, are of great importance. Scientifically based fishing is impossible without a preliminary study of questions about the size of crayfish stocks, the dynamics of its number, features of distribution, distribution among them parasites and symbionts of other aspects of its biology. In this regard, studies of the ecological and morpho-physiological variability of crayfish depending on living conditions, the level of parasitemia, as well as the density, number and size-sex structure of the population are of considerable interest, the study of which has received relatively little attention until now. Knowledge of the regularities of these relationships will allow, on the basis of relatively simple methods of morpho-physiological and parasitological indicators, to quickly assess the state of the population exposed to any adverse conditions, in particular, intensive fishing. Based on the study of literature data on the fauna of crayfish parasites and symbionts, morpho-physiological variability and ecology of long-finned crayfish populations, separate scientifically based bases of rational fishing for the region were proposed