The possibilities of using of captive and domestic broodstocks for saving of natural populations: 1. Acipenseriformes (part 1)

Abstract

In last years the stocks of Russian species of sturgeons decreased to critical level which can be followed by their complete extinction in nature. As a result, the number of sturgeons beginning spawning migration into rivers are extremely small, but Astrakhan sturgeon hatcheries continue release annually about 35 mln fry using own broodstocks of two types — captive and domestic ones. However the releases of offspring of domestic broodstock are extremely discussible. On one hand, creation of such broodstocks could avoid the complete extinction of natural populations of Adriatic sturgeon Acipenser naccari in Po River and European sturgeon A. sturio in Gironde estuary. On other hand, long-term practice of commercial fish farming had shown that even the accidental refugees from sea cages or fresh-water ponds caused great harm to natural populations of same species. Hatchery individuals were undergoing different selection than fish in wild nature and had poorly formed reflexes (searching for food and avoiding predators). Besides a progressive decrease in genetic diversity with each generation could be seen in such fry due to limited number of parents (the Ryman-Laikre effect). However the creation of captive and domestic broodstocks of endangerous species and subspecies (Azov beluga Huso huso maeotica, fringebarbel sturgeon Acipenser nudiventris, Sakhalin sturgeon Acipenser mikadoi) and extinct populations (Baltic sturgeon Acipenser oxyrinchus) remains the only way to release hatchery juveniles. The first part of presented review is devoted to creation and using of captive and domestic broodstocks for conservation-type sturgeon fry releases in Russia and other countries.