Assessment of reproductive hormones level in baleens of bowhead whales and in serum of gray whales off Chukotka (Russia)
Sergey V. Naidenko, Pokina S. Klyuchnikova and Dennis I. Litovka
The level of reproductive hormones (testosterone and progesterone) in the serum of gray whales (six individuals) and Pacific walrus (4 individuals) harvested in Chukotka was analyzed. Immature gray whales had average level of progesterone 0.37 ± 0.04 ng/ml and testosterone 0.58 ± 0.13 ng/ml. Such low concentrations are associated with the age of whales that have not yet reached puberty. Pacific walruses had an average progesterone level of 0.97 ± 0.40 ng/ml (lim=0.47÷2.18) and testosterone 0.31 ± 0.05 ng/ml (lim=0.24÷0.46). For the first time in the Russian Federation, the level of progesterone and testosterone in the Bowhead whales was determined. The analysis made it possible to trace changes in the hormonal status of animals during first 9 years of life of two individuals. It was shown that puberty in the bowhead whale (an increase in testosterone levels) is observed at the age of about 9 years. It was noted that newborn cubs (under six months) had a very high level of testosterone, which theoretically could be connected with their exposure to maternal testosterone during the period of animal embryonic development. We will continue an extremely promising study of the hormones of whales, walruses and seals harvested in the Chukotka coastal waters with the Chukotka Autonomous Region Government support.