Dependence of the Testosterone Concentration in the Blood of Male Beluga Whales Delphinapterus leucas on the Age and Season.

The results of a study of the reproductive system of male beluga whales (Delphinapterus leucas), in particular, an analysis of the content of serum testosterone in blood serum samples during the growth and development of animals, are presented. This study was conducted on male whales kept in semi-free conditions of an open-air marine enclosure complex in the Barents Sea. A total of nine belugas were examined, and 50 samples were analyzed. Blood sampling was carried out from the ventral or dorsal vein of the caudal fin. The testosterone content in the samples was determined by the method of heterogeneous enzyme-linked immunosorbent assay (ELISA). A comparative assessment of the concentration of this steroid hormone in young and mature animals showed a positive linear correlation between the level of testosterone secretion and the age of the animal. Studies have shown that the sexual maturity of male beluga whales occurs by the age of 8–10, when serum testosterone levels of 15 nmol/L or higher are reached. [ABSTRACT FROM AUTHOR]