Биология и современное состояние запаса анчоусовидной кильки (Clupeonella engrauliformis Borodin)

Abstract

In the Caspian Sea sprats is the name of the numerous small fish of herring family (Clupeonella). One of Clupeonella representatives is anchovy sprat. It differs from other types of kilka not only in appearance, but also in its way of life. A brief biology of the species and the state of ecosystem of the Caspian pelagic zone has been described. Anchovy kilka has been a leading targeted fish for over 50 years. Invading the Caspian Sea by ctenophore-mnemiopsis has undermined the stocks of anchovy sprats and caused the crisis of anchovy kilka fishing. Recently, there has been observed a slight increase in the number of the species. The survey materials confirm the increase in the number of juveniles in the studied catches. There are presented the materials from the last six years (2014–2019) of observations (eight research runs), shown the dynamics of abundance, biomass, spawning females, and total fertility of the population. Spawning efficiency and survival rate in early ontogenesis are analyzed. The relationship between kilka survival rate and the number of emerging generations is stated. Recommendations on restoring the stock of anchovy kilka are given. To restore the ecosystem of the Caspian Sea there has been proposed the invasion of a new species – ctenophore-beroe (Beroe ovata), which, due to the structure of its mouthparts eats only jelly-skinned (ctenophore-mnemiopsis, exceptionally) and can significantly reduce the number of ctenophore-mnemiopsis