ПРОХОДНЫЕ ОСЕТРОВЫЕ (ACIPENSERIDAE, ACTINOPTERYGII) р. ДОН ВЫШЕ ЦИМЛЯНСКОГО ГИДРОУЗЛА

Abstract

Based on the literature, non-published and survey data, information on the occurrence of anadromous sturgeons after the regulation of the Don River downstream and upstream of the Tsimlyansk Dam is given. There were two peaks of mature adults approaching the dam, namely, in the 1950s and 1980s. The first mass peak was associated with the wild population existed then; the second one was a result of mass artificial breeding. At the first stage, the sturgeon (Acipenser gueldenstaedtii Brandt et Ratzeburg, 1833) and beluga (Huso huso (Linnaeus, 1758)) prevailed below the dam; at the second one, just the sturgeon did. Since 1955, only 21 individuals of anadromous sturgeons were transported through the dam by a fish ladder. During 1952-1961, 1,145 individuals were transported into the reservoir, including 218 belugas. Separate beluga individuals were transported later on as well. There is evidence of the presence of young beluga individuals from natural spawning in the reservoir before the 1970s. The latest known adult sturgeon and stellate sturgeon (Acipenser stellatus Pallas, 1771) in the reservoir were noted in the 1980-90s. Separate beluga individuals have been met until now. The youngest of the noted individuals belong roughly to the generations of the early 1990s. It is concluded on the existence of an extremely low-abundant landlocked form of the Azov beluga in the reservoir.