Hatchery stock
enhancement and conservation of sturgeon, with an emphasis on the Azov Sea
populations
M.S. Chebanov, G.I. Karnaukhov, E.V.
Galich, Yu.N. Chmir-2002
Journal of
Applied Ichthyology, 18(4-6): 463-469
Abstract:
The regulation of river flows hampered
natural reproduction of sturgeons in the Azov Sea basin. To develop a
long-term strategy for stock enhancement, it is necessary to assess the
effectiveness of the hatchery stocking programs. As a result of 60%
reduction in river flow, the natural propagation of sturgeon in the Kuban
River has been absent for the past 25 years. Up to 30 million juveniles
of Russian and stellate sturgeon were released annually from five sturgeon
hatcheries, the main sources of sturgeon recruitment in the Sea of Azov. The
hatchery stocking strategy was aimed solely at the release of a large number
of juveniles, utilizing only the most mature broodfish of the spring
spawning run for breeding. While the monitoring of age, weight and
physiological conditions of the broodstock during the period of hatchery
breeding did not reveal significant changes, the spawning run was
dramatically shortened (to 15 days, compared with several months in the
previous history of the spawning run) and included only fish with advanced
gonadal maturity. The analysis of protein polymorphism suggested significant
changes in stock genetic composition of stellate sturgeon related to the
hatchery practices and stocking allopatric populations from the Caspian Sea.
The traditional methods and technology of the artificial reproduction appear
to be ineffective under present ecological conditions. The different,
long-term, management strategy should be based on new concepts of stock
enhancement and genetic assessment, to preserve the intraspecific diversity
of sturgeon. This includes novel hatchery methods for controlled maturation
and spawning of different ecotypes, and production and stocking of
high-quality juveniles in the year-round timetable. Conservation of the Azov
Sea species and their unique spawning ecotypes is currently supported by the
Federal Living Gene Bank in the Krasnodar Region, which maintains over 7000
adults of the endangered species and populations. This genetic collection is
used for research and restoration of the biodiversity of sturgeon in the Sea
of Azov.
(Krasnodar Research Institute of
Fisheries, 12, Oktyabrskaya St., Krasnodar 350063, Russia. E-mail: chebanov@sturg.kuban.ru)