Biology and Distribution of Stellate tadpole-goby Benthophilus stellatus and Don tadpole-goby B. durrelli (Teleostei: Gobiidae)

Abstract

Size-age and sex population structure have been studied for the aboriginal stellate tadpole-goby Benthophilus stellatus and Don tadpole-goby B. durrelli in the Don River basin. The females of Don tadpole-goby mature at a body length of about 35 mm, stellate tadpole-goby females, at 50 mm. Most breeders of Don tadpole-goby (~74%) are characterized by one-time spawning, stellate tadpole-goby spawns three times. The duration of the breeding season is about 3.5 and 1.5 months, the individual absolute female fecundity is 0.2–0.6 and 1–3 thousand eggs, respectively. All breeders of Don tadpole-goby die after spawning in the second year of life, an insignificant part of stellate tadpole-goby population lives up to three years. The food spectra, size and biotopic variability, the degree of food similarity, and the selectivity of food organisms in both species have been analyzed. The species are characterized by the similarity in feeding and high feeding flexibility. In the Tsimlyansk Reservoir, the main food objects for tadpole-gobies are mosquito larvae and the mollusk Lithoglyphus naticoides, in the lower reaches of the Don River, various crustaceans. We assume three species of tadpole-goby (Don, stellate tadpole-goby and Makhmudbekov tadpole-goby B. mahmudbejovi) inhabit currently in the Volga River reservoirs. Don tadpole-goby has also settled in the lower reaches of the Volga River. Apparently, its range includes the Black Sea, in addition to the native Sea of Azov and newly mastered Volga River basins.