Reproduction

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Reproduction is one of the important physiological systems that are important in the life cycle of living organisms including fish. The main objective of the reproduction is to maintain the existence of the species and therefore fish has a strategies and tactics to achieve this objective. The reproduction behaviours are important to be studied in relation to know the population dynamic of fishes and their spawning seasons. This information is very crucial in relation to the development of breeding technology for aquaculture and conservation (restocking) purposes. This paper reviews the reproductive strategy, fecundity and spawning frequency of fishes. Studies on reproductive behaviour of fish are important and a basic requirement for improvement and effective fishery resources management and conservation (Ali & Kadir, 1996; Ezenwaji et al., 1998; Brewer et al., 2008; Grandcourt et al., 2009), determination of basic life-history information and for assessing the impacts of environmental variability on the dynamics of fish populations (Schlosser, 1990). Information on the reproductive system is essential for the development of the commercial aquaculture of an aquatic species (Muchlisin, 2004). Natural challenge leads the fish to the maximization of the lifetime production of offspring, and more importantly to maximization of survivorship of offspring until adulthood (Murua & Sabodiro-Rey, 2003). Herein, we reviewed some aspects of reproductive biology of fishes such as reproductive strategy, fecundity and spawning frequency. The reproductive strategies of fishes are often reflected in the anatomical differences between the sexes, male and female. The objective of a reproductive strategy is to maximize reproductively active offsp... ... middle of paper ... ...ed to produce fewer eggs (Matthews, 1998). In species whose eggs develop in open waters or are freely scattered on the bottom, population strength is usually maintained by high fecundity relative to the small egg size. Development of adaptations for care of progeny is accompanied by decreased fecundity and usually increased egg size with greatly increase energy resources for embryo and enables the embryo to develop without obtaining exogenous food, and to reach active life at a higher level of differentiation and ensuring higher survival (Ginzburg, 1972). On the other hand, the relative fecundity is based on weight of fish. In most fish the number of eggs does not change significantly as the season progresses and the relative fecundity is constant through the season (Bagenal, 1978). For comparison fecundity among fishes, the relative fecundity is commonly used.

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