Factors Influencing Early Survival and Growth of Laboratory‐reared Pacific Bluefin Tuna,Thunnus orientalis,Larvae |
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| Authors: | Yosuke Tanaka Kazunori Kumon Kentaro Higuchi Takeshi Eba Akefumi Nishi Hideki Nikaido Satoshi Shiozawa |
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| Affiliation: | 1. Research Center for Coastal Fisheries and Aquaculture, Tohoku National Fisheries Research Institute, Japan Fisheries Research and Education Agency, Iwate, Japan;2. Amami Laboratory, Research Center for Tuna Aquaculture, Seikai National Fisheries Research Institute, Japan Fisheries Research and Education Agency, Kagoshima, Japan;3. Research Center for Tuna Aquaculture, Seikai National Fisheries Research Institute, Japan Fisheries Research and Education Agency, Nagasaki, Japan;4. Shibushi Laboratory, National Research Institute of Aquaculture, Japan Fisheries Research and Education Agency, Kagoshima, Japan |
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| Abstract: | The collection of fertilized eggs for mass culture of Pacific bluefin tuna (PBT) relies on the spontaneous spawning of broodstock in captivity, and the spawning season of the broodstock is generally from mid‐May to September. The diameter of fertilized eggs from the broodstock decreases during the spawning season. To investigate the influence of three potential factors, the egg diameter (larger or smaller), the rearing water temperature (25 or 28 C), and the aeration rate during the night (strong or weak), on early survival and on growth of PBT larvae, replicate trials were conducted to assess these three factors until 7 d after hatching (d.a.h.). At 7 d.a.h., survival rates of larvae reared with strong nighttime aeration were found by a three‐way ANOVA to be significantly higher than for larvae reared with weak aeration. Furthermore, growth rates of PBT larvae hatched from larger eggs were significantly faster than those from smaller eggs. However, a significant difference in the survival rate was not detected for the factors, egg diameter and rearing water temperature. The results indicate that rearing with strong nighttime aeration significantly improved the early survival of PBT larvae and the egg diameter (a proxy for egg quality) and influenced growth. |
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| Keywords: | aeration egg diameter larvae Pacific bluefin tuna water temperature |
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