Reproductive System of Amu-Dar Shovelnoses - Big ShovelnosePseudoscaphirhynchus kaufmanni and Little Shovelnose P. hermanni(Acipenseridae)

摘要

A study on gametogenesis in the big Pseudoscaphirhynchus kaufmanni and little P. hermanni Amu-Dar shovelnoses was performed. It was shown that processes of gameto- and gonadogenesis are similar in these species and proceed according to a scheme common to all acipenserids. In recent years, females and males of the dwarf form of P. kaufmanni are reaching sexual maturity at an earlier age (at 4-5 and 3-4 years, respectively), but at the same body length and relative gonad weight as before. For the first time, females of P. kaufmanni with gonad microstructure were found, which suggests their unusually early sexual maturation at small length and weight. Females of P. hermanni mature at an age of 4-5 years at a body length and weight similar to indices of the dwarf form of P. kaufmanni. Both species of shovelnoses spawn mainly in April at a water temperature of 13-20 degree C. In recent years, various anomalies in the micro- and macrostructures of gonads of the studied species have been recorded; in P. kaufmanni, their range is wider than in P. hermanni.