WWW.WAS.ORG • WORLD AQUACULTURE • JUNE 2013 55 In an attempt to counter the catastrophic decrease in populations of sturgeon and the accompanying pressure on breeders, artificial reproduction in hatcheries has an important place in Russia. Fish hatcheries supplying mature breeders is a faster way to obtain sturgeon broodstock, using new biotechnological methods. When establishing broodstock of sturgeon for fish hatcheries, it is important to conserve the integrity of the gene pool and carefully plan the release of these fishes into natural water bodies (Popova et al. 2001). More than 20 broodstock lines have been established across several fish hatcheries in Russia. The main problems are estimation of optimal conditions for breeding, joint breeding of different sturgeon species and age groups, and a search for effective methods of selective breeding for the development of highly productive broodstock for breeding and commercial purposes (Burtsev et al. 1989, Vasil’eva 2000). Development of productive broodstock is accomplished in two ways: domestication of wild breeders and rearing from “eggs to eggs.” Domestication of wild sturgeon is realized by obtaining sexual products from them over their lifetimes. The basis of successful domestication is training fish to accept formulated feeds and acclimate to unusual environments. Formation of broodstock on the principle of “eggs to eggs” is realized by obtaining offspring from breeders and rearing them in controlled conditions to maturation. The use of females captured from natural water bodies, with eggs in the second stage of maturation, is a common practice. Females are then bred in hatcheries until the end of gametogenesis. Formation of broodstock in this manner has a spontaneous quality; there can be no selection of fish specific to sturgeon breeding (Podushka 1997, Barannikova et al. 2000). One advantage for fish hatcheries in using mature breeders is faster maturation of males and females, using different combinations of breeding methods, manipulation of environmental factors and other opportunities (Samoilenko 2011). With development of modern biotechnology, the most sure and effective method of faster maturation of sturgeon is the use of industrial breeding, particularly in installations with closed water supplies. The main purpose of our investigations is to develop new concepts of productive sturgeon broodstock formation and improve existing methods of broodstock exploitation in installations with closed water supplies. The use of recirculation systems with complex regulation of Modern Sterlet Acipenser ruthenus Broodstock Management in Southern Russia E.N. Ponomareva and M.M. Belaya basic environmental factors (temperature, light, feeding regime, mineral content of water and water use) allows juveniles and breeders to achieve maturation quickly, approximately twice as fast as in nature. In conditions of intensive breeding, the maturation of males is faster than that of females. Sterlet mature at 2 years, sturgeon of Lena River at 2-3 years, Russian sturgeon at 3-4 years and beluga at 4-5 years. The method of early maturation of females requires further improvement (Samoilenko 2011). The object of this investigation was sterlet–a freshwater, early-maturing species of sturgeon. Two subspecies of sterlet were used: from populations in the Volga and Don rivers. In formation and exploitation of fish broodstock, decreased heterogeneity of offspring is a problem because the supply of breeders used for spawning is often limited. Inbreeding leads to deterioration of physiological status with a decrease in immunity and vitality of offspring. To avoid the negative consequences of inbreeding, the quantity of breeders must be increased. This is very difficult because of a current lack of sturgeon breeders. To increase the population heterogeneity, it is reasonable to exchange the sexual products (milt) between fish hatcheries. However, broodstock in different hatcheries do not always mature at the same time. Furthermore, the quality of milt can be unsatisfactory and quality can decrease during transportation beyond usability, posing a threat to the entire spawning campaign. Maintenance of an optimal level of genetic diversity in hatchery populations is a primary and simultaneously difficult undertaking because the decrease of genetic heterogeneity results in deterioration of fish quality. In nature, there is adaptive flexibility and the opportunity for populations to adapt to different environmental conditions. In hatcheries, the reduction of genetic diversity results in the loss of unique properties and characteristics of these engineered fish populations. Maintenance of balance among traits is the basis for extended exploitation of hatchery populations. We have developed the following criteria for broodstock formation based on this principle. The effective number of broodstock (Ne) should be at least 100200 breeders of different ages and the quantity of females and males should be equal to decrease the risks of inbreeding. Other criteria for broodstock development provides for decreased inbreeding and genetic drift. This can be achieved by collection of broodstock from different areas. Our broodstock population was formed from mature and nearly mature fish that were caught in natural waters at different (CONTINUED ON PAGE 56) The maintenance of optimal heterogeneity and decrease of probable inbreeding during broodstock collection is achieved by fully renewing broodstock every 4 years (8 reproductive cycles) with an annual change of 30 percent of breeders with different reproductive origins: 10 percent from hatchery broodstock, 10 percent from the wild and 10 percent from females and cryopreserved sperm.
RkJQdWJsaXNoZXIy MjExNDY=