The efficacy of three different algae (Ascophyllum nodosum, Porphyra yezoensis, and Ulva pertusa) were compared in fingerling red sea bream Pagrus major. Oregon moist diet containing 5% of algae meal were fed for 41 days and the effects were monitored in terms of growth, feed efficiency, and body composition.Feeding algae commonly elevated body weight grain, and tended to increase feed efficiency and muscle protein deposition. Algae-fed groups were higher in liver glycogen and triglyceride accumulation in muscle. Feeding Porphyra showed the most pronounced effects on growth and energy accumulation, followed by Ascophyllum and Ulva. The results suggest the practical efficacy of using algae as a feed additive for the effective use of nutrients in cultured fish.

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Four highly variable microsatellite loci, Acs1*, Acs3*, Acs4* and Acs9*, were isolated and then used to investigate genetic diversity and population structure in black sea bream, Acanthopagrus schlegeli, collected from wild populations of six locations (western Japan and southern Korea), / and hatchery stock and post-stock populations from Hiroshima Bay. When allelic segregation of each .' microsatellite locus was examined using the single spawning pair and their progeny, all loci were well fitted to the Mendelian manner of inheritance. The genetic variations at these loci in the eight populations revealed high levels of variability. In the wild populations the mean number of alleles per locus was 10.8-13.5, and the mean observed hetrozygosity was 0.755-0.828. In contrast, these values in hatchery stock population were 10.0 and 0.776, respectively. Genetic distance indicates the existence of geographic divergence between western Japan and south Korea, and little genetic differentiation among populations in western Japan.

As the fact that feeding Spirulina can improve carcass uality of fish, this study describes the effect on muscle protein in red sea bream, Pagrus major. The ;fsh were fed on a diet supplemented with 2% Spirulina for 95 days under commercial rearing conditions. Spirulina feeding elevated protein synthesis, which was estimated by muscle RNA/DNA and RNA/protein ratios. Muscle protein was fractionated into sarco lasmic, myofibrillar, alkali-soluble and stromal fractions. The stromal fraction was si nificantly gigher in the Spirulina-fed roup. The proportion of the fractions approached that of wi6 fish somewhat by Spirulina-feeding. '!he results possibly indicate that Spirulina contributes to elevate protein assimilation and increase stromal fraction.

No abstract