市販ソフトドライペレットを給餌したブリの採卵結果

Abstract

Yellowtail Seriola quinqueradiata broodstocks, captured by set-net fishery and reared on raw fish for one and a half years, were fed frozen raw fish (RF group), moist pellets (MP group), or soft dry pellets (SDP group) for 6 months before egg collection. The MP group received a 1:1 diet mixture consisting of a formula feed prescribed by the National Research Institute of Aquaculture and raw fish, whereas the SDP group was fed a commercial soft dry pellet. After 6 months the fifh in each net-cage were injected with hormone (HCG) to induce spawning, and eggs were collected from each broodstock either after induced spawning or by strip spawning of adults followed by the dry method of insemination. Parameters of the SDP group such as number of eggs per spawner, fertilization rate, hatching rate, and survival rate of the larvae were compared with those of the RF and MP groups. The success of egg collection from the SDP group was as good as that from the MP group, and those from the SDP and MP groups were superior to that from the RF group. These results clearly indicated that both DP and MP were efficacious for broodstock management of yellowtail and their egg collection.