CHAPTER IV
PREPARATION OF SPAWNERS
4.1 Selection of spawners
The number of spawners to be conditioned and used varies according to the number of the young abalone to be produced and to the rearing method and technical devices available. Up to the shell length of 5 mm, the abalone survival rate, which may range from 1– 40 %, is affected by the rearing method and technical conditions of the devices. Therefore, bearing in mind these conditions and the number of eggs to be spawned a sufficient number of spawners should be used. The ratio of female and male is 4:1, and a good spawner should be at least three years old and 7–9 cm in shell length. The bigger the spawner, the more eggs it bears (Fig. 9). About 80 % of mature eggs are usually released into the seawater. It is advisable to catch spawners in March/May and in October/November when the water temperature is comparatively low. Much care should be given during the collection of spawners and transportation to the breeding station.
Abalones with a fleshy foot are desirable as spawners. Specimens with a less developed foot and immature gonads should be replaced with mature ones.
Figure 9.
Figure 9. Relationship between abalone shell length and fecundity.
CHAPTER IVPREPARATION OF SPAWNERS4.1 Selection of spawnersThe number of spawners to be conditioned and used varies according to the number of the young abalone to be produced and to the rearing method and technical devices available. Up to the shell length of 5 mm, the abalone survival rate, which may range from 1– 40 %, is affected by the rearing method and technical conditions of the devices. Therefore, bearing in mind these conditions and the number of eggs to be spawned a sufficient number of spawners should be used. The ratio of female and male is 4:1, and a good spawner should be at least three years old and 7–9 cm in shell length. The bigger the spawner, the more eggs it bears (Fig. 9). About 80 % of mature eggs are usually released into the seawater. It is advisable to catch spawners in March/May and in October/November when the water temperature is comparatively low. Much care should be given during the collection of spawners and transportation to the breeding station.Abalones with a fleshy foot are desirable as spawners. Specimens with a less developed foot and immature gonads should be replaced with mature ones.Figure 9.Figure 9. Relationship between abalone shell length and fecundity.
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