Proceedings of the Third World Fisheries Congress: Feeding the World with Fish in the Next Millenium—The Balance between Production and Environment
Effect of Dietary Vitamin E and C on the Reproduction Performance of Chinese Mitten Crab Eriocheir sinensis
Chun-xiang Ai, Li-qiao Chen, Zhong-liang Zhou, Xiao-bo Wen
Shrimp and crab aquaculture has grown impressively in many developing countries where this activity has attained great economic and social importance. A barrier to the development of shrimp and crab farming is an insufficient supply of seed, which is presently gathered from natural sources. Thus, one of the most important and fundamental approaches to artificial seed production is to satisfy the ever-growing demand on crustacean breeders to ensure a year-round supply of high-quality fertile eggs that result in high survival and growth rates, comparable to those occurring naturally (William and Addison 1990). For this purpose, the cultivation of broodstock that produce high-quality eggs is important. The nutrition of broodstock fishes and crustaceans plays a major role in achieving reproductive success and has a considerable influence on gonad maturation, fecundity, egg hatchability, and viability of larvae (Teshima and Kanazawa 1983; Watanabe et al. 1989; Bray and Lawrence 1992).
The lack of clearly defined nutritional requirements for reproduction has been an obstacle to both the development of satisfactory dry feeds for broodstock and the production of nauplii of consistently high quality. The fresh diet compositions commonly used (e.g., shrimp, squid, crab, fish, brine shrimp, bloodworm, mussel, and oyster) are expensive; may deteriorate water quality; and may vary in nutritional quality with species, age, maturation state, season, and location. Hence, studies on the nutritional needs of cultured shrimp and crab broodstock aimed at improving the reproductive performance and the quality of their offspring are needed.
The role of nutrition in the reproductive processes of crustaceans has been emphasized by Harrison (1990), and an effect of broodstock diet on spawning frequency, spawn size, and hatching has been described by comparing animals fed fresh foods with those fed compound diets (Nascimento et al. 1991). Vitamin-specific requirements of broodstock have been investigated by using a defined diet with determined basal composition: dietary vitamins A, E, and C enhance ovarian development of kuruma shrimp Penaeus japonicus (Alava et al. 1993a, 1993b), and supplemental vitamin E in broodstock diets can improve the reproduction performance of Indian white prawn Penaeus indicus and tiger prawn Penaeus monodon (Cahu et al. 1995; Wang 1999). Diets high in vitamin C also lead to an egg quality superior to the low-concentration group in Indian white prawn. The effect of these compounds on embryonic development also is strongly suggested in other organisms such as insects (Draper 1980) and fish (Dabrowski and Ciereszko 1996; Terova et al. 1998a, 1998b).
The Chinese mitten crab Eriocheir sinensis is commercially important and commands a high price because the demand for crab meat in both local and international markets in China is expanding rapidly. Significant advances have been made in this industry during recent years. Successful and profitable cultivation of Chinese mitten crab depends heavily on several parameters, including the constant and reliable availability of seedstock supplies. Semi-intensive and intensive production development requires a large number of good-quality seedstock. However, as for other crustacean species, no data about the nutritional influences on reproduction of the crab are available. The aim of this study was to investigate the effects of α-tocopherol and ascorbic acid on gonad development, fecundity, and egg hatchability of Chinese mitten crab.