Efficient egg collection by spontaneous spawning in a tank of the Japanese smelt, Hypomesus nipponensis in Lake Ashinoko, Kanagawa prefecture [Japan]
2003
Kitsukawa, M. (Ashinoko Fishery Cooperative Union, Hakone, Kanagawa (Japan)) | Ohba, M. | Hirose, H. | Hirose, K.
Abstract: Hand stripping method is generally used to obtain the fertilized eggs of the Japanese smelt Hypomesus nipponensis. However, the method is laborious and takes much time, so the efficient improvement for egg collection and labor saving were needed for the mass production of fertilized eggs and larvae. We have recently developed the spontaneous spawning method in a tank. This method is very efficient to obtain a large number of fertilized eggs when compared to the hand stripping. Mature male and female smelts were caught by the setting nets in Lake Ashinoko. They were kept in 1.5 t spawning tank with running water through a night. On the following day the broodstocks spawned spontaneously in the tank, and the fertilized eggs were efficiently collected. In an example, 71,018*10E4 fertilized eggs from 3,427 kg broodstock were obtained by the spontaneous spawning method for 37 days in 2002. The rate of eyed eggs were 86.7-96.1%, indicating almost maximum value in the mass production level. By this newly developed method, number of collected egg per hour was about double when compared to the usual stripping method. Therefore, this spontaneous spawning in the tank of Japanese smelt is very efficient to obtain the fertilized eggs, and labor saving method. Also, this is expected to be applied for other fishes.
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