УСОВЕРШЕНСТВОВАНИЕ ТРАЛОВОГО ПРОМЫСЛА ТЮЛЬКИ В АЗОВСКОМ МОРЕ В СОВРЕМЕННЫХ УСЛОВИЯХ ВОССТАНОВЛЕНИЯ ПОПУЛЯЦИЙ ОСЕТРОВЫХ РЫБ

Abstract

Background. At present, the Black and Caspian Sea sprat (tyulka) is the least exploited species of the aquatic biological resources in the Azov and Black Sea Fishery Basin, although it has always been a valuable fishing target and a possible reserve pool for the increase of fish catches in the Basin. In the recent years, with the increasing number of midwater trawls allowed for using in the Black and Caspian Sea sprat (tyulka) fishery, all vessels transitioned to its trawl fishing; however, its total catch is decreasing, and the fishing results of these vessels are on the decline. Relevance. Taking into consideration the stock restoration occurring to the sturgeon fish species in the Azov Sea Basin in the recent years, it is necessary to take measures for maintaining this trend, as the Black and Caspian Sea sprat trawl fishing can result in increased mortality or injury of sturgeon fish and considerably damage their population. With a substantial decrease in the Black and Caspian Sea sprat fishing stock, the matter of stock restoration of the sturgeon fish species in the Azov Sea can induce the prohibition of the trawl operations in this water body, including the complete ban of the insufficiently profitable trawl fishing of the Black and Caspian Sea sprat in its current form. The aim of this article is to examine the design of the midwater trawls used in the Black and Caspian Sea sprat fishing in the Azov Sea, to investigate the global best practices in the trawl selectivity improvement, and to substantiate the main design characteristics for the specialized tyulka midwater trawls and means of their selectivity improvement. Methods. The standard methods of sample collection and data processing that could characterize fishing methods, gears and techniques for harvesting aquatic bioresources have been used. Results. The designs for the specialized trawls for the Black and Caspian Sea sprat fishing (exploitation) and methods for their selectivity improvement have been developed. Conclusion. These specialized trawls with the sorting units and a new principle of using otter boards (trawl doors) can increase fishing selectivity and mitigate possible damage inflicted by trawling to the populations of sturgeon fish species in the Azov Sea.