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Mature females |
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This is extremely reliable in terms of larval quality. Healthy females are collected from their natural spawning grounds where they have had the advantages of appropriate nutrition and oceanic water quality, have been subject to natural selection processes, and have not been exposed to environmental stresses which may occur in captivity. The disadvantages are the regional availability of suitable indigenous species, the changing seasonal and daily availability of mature females, the expense of capture and transfer, and the lack of potential for offspring improvement through genetic selection. The mechanics of this system are simple: mature wild females are placed in suitable spawning vessels with high quality, oceanic-character water, and allowed to spawn. After spawning, the females are not used again and the healthy, nature-prepared larvae are reared through well understood techniques (Bray & Lawrence, 1992). This system is used extensively today in Taiwan and the Philippines with P. monodon, with P. vannamei in Ecuador, and with P. chinensis and P. penicillatus in China. Because the collection of females which are ready to spawn limits culturists to indigenous species which may not be the most suitable, and is dependent on seasonal availability, migratory movements, weather, and natural rhythms, this system is not feasible in many locations. Furthermore, this method does not allow the longer-term goal of developing improved domestic stocks with strong growth and survival characteristics, or of maintaining disease-free captive stocks, and may disrupt fishery production (Bray & Lawrence, 1992). This system requires transportation of the broodstock animals. | |