Arnil C. Emata

Induced spawning and early life description of the mangrove red snapper, Lutjanus argentimaculatus.

Abstract Wild-caught mangrove red snapper, Lutjanus argentimaculatus, reared in a concrete tank for 1 year, spontaneously matured in June 1992. On 19 August 1992, a sexually mature female and male (4.6 and 3.2 kg body weight, respectively) were administered a single intramuscular injection of HCG 1500 IU·kg−1 body weight. Spawning occurred 27 h after injection. Hatching occurred 16 h after spawning at 28°C and 32 ppt. Yolk resorption was completed 72 h after hatching. Growth was slow in the first week but rapid in the second and third weeks. Egg and larval development is similar to that of other lutjanids. Larval rearing revealed two critical periods: days 3–5 and days 18–20. Future studies must be geared to avoid mass mortality of the larvae during the critical stages for mass seed production.

Salinity tolerance of larvae of the mangrove red snapper (Lutjanus argentimaculatus) during ontogeny

Abstract Salinity tolerance and the effects of salinity on growth, condition factor and chloride cell (CC) densities were evaluated for Lutjanus argentimaculatus larvae during ontogeny. Tolerance of L. argentimaculatus larvae to abrupt changes of salinity from 32 ppt varied with age. Periods to 50% mortality (LT 50 ) were significantly ( P L. argentimaculatus larvae, regardless of age (0-, 7-, 14-day-old), showed significantly longer LT 50 when abruptly transferred to 8 and 16 ppt than for transfers to 24 and 40 ppt ( P L. argentimaculatus larvae at 16, 24, 32 (control) and 40 ppt was not significantly different either at the end of the first rearing phase (days 0–21) or second phase of rearing (days 22–50). Survival was significantly lowest at 40 ppt (4.3%) at the end of first phase of rearing ( P K ) of larvae reared at lower salinities was significantly higher than that of fish at 40 ppt ( P

Advanced broodstock diets for the mangrove red snapper and a potential importance of arachidonic acid in eggs and fry

Mangrove red snapper fed advanced broodstock diets containing squid meal and squid oil exhibited higher hatching rates, cumulative survival and survival activity index than those fed a basal diet or a basal diet supplemented with mixture of antioxidants. On the other hand, fatty acid analyses of ovaries and fry of wild fish and eggs and larvae of broodstock fed raw fish revealed high arachidonic acid (ARA) and docosahexaenoic acid (DHA) levels and relatively lower eicosapentaenoic acid (EPA) levels consequently showing high ARA/EPA and DHA/EPA ratios compared to cold water species. This suggests that ARA may be nutritionally more important for egg and larval development and survival in tropical marine fish and its supplementation in broodstock diets may enhance reproductive performance of mangrove red snapper.

A practical broodstock diet for the mangrove red snapper, Lutjanus argentimaculatus

Abstract A practical broodstock diet (39% protein, 8.6% lipid) was formulated for the mangrove red snapper as part of a project to ensure consistent production of good quality eggs and larvae through broodstock nutrition. Reproductive performance of mangrove red snapper broodstock fed practical diet ( n =14 females) was enhanced in comparison to those fed raw fish ( n =12 females). Broodstock fed practical diet had total egg production of 82.34 million from 68 spawns for two spawning seasons while broodstock fed raw fish produced 77.64 million eggs from 66 spawns. Mean percent of egg viability, hatching rates and percent of normal larvae did not vary between the two groups. However, broodstock fed the practical diet had higher mean cumulative survival rate of eggs to normal larvae (40.4%) than that of broodstock fed raw fish (35.2%). Also, survival activity index (4.08) of broodstock fed practical diet was higher than that of broodstock fed raw fish (2.97). The results clearly indicate the improvement of reproductive performance of mangrove red snapper fed practical diet. Further studies should focus on the specific nutrients that can ensure consistent production of high quality eggs and larvae of the mangrove red snapper to support its aquaculture.