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Land‐based cultured juvenile Pacific bluefin tuna Thunnus orientalis (PBT) have high mortality rates due to collisions or contacts with tank walls after about 30 days of hatching. To determine the effect of night‐time lighting on their survival, juvenile PBT were reared under four different night‐time light intensities (0, 5, 15 and 150 lx) for 9 days, followed by a 3‐day observation period. High‐intensity, night‐time lighting (150 lx) significantly improved the survival rate (75.8%; P < 0.001) compared with the unlit control group (0 lx, 64.3%). The survival rate in the high‐intensity group decreased after the end of the lighting period. Lighting did not influence whole‐body cortisol levels, glucose levels, or diel changes in plasma cortisol levels. In contrast, the survival rates of fish exposed to light intensities between 5 and 15 lx were slightly lower than that of the unlit control group. These results suggest that providing night‐time lighting of 150 lx or higher is an effective method for reducing the mortality of cultured PBT.

This study investigated the effect of feedings taurine-enriched rotifers on the growth and development of larval red sea bream (RSB). Rotifers incubated in taurine-enriched water at a taurine concentration of 800 mg L À1 (T-800) and 0 mg L À1 (T-0) were fed to larvae from 3 to 20 days after hatching (DAH). Notochord length, body weight and specific growth rate of T-800 group were significantly greater than those of T-0 at 14, 17, 9-11 and 18-20 DAH. Taurine content of larvae in the T-800 group increased rapidly from 11 DAH and thereafter remained significantly higher than T-0. Flexion larvae firstly appeared in both groups at 8 DAH, however, at 20 DAH post-flexion larvae were significantly more abundant in T-800 than T-0. While nucleic acid and protein contents (lg mg À1 wet fish) showed remarkable changes, ontogenetic growth in RSB larvae stage was observed to switch from hyperplastic growth to hypertrophic growth with the start of the flexion stage. Although a similar change in nucleic acid contents was observed between the two groups, the protein content (lg fish À1 ) and protein/DNA ratio of T-800 remained higher than that of T-0 during the hypertrophic growth period. These results suggest that dietary taurine accelerates the growth and development in RSB larvae especially during hypertrophic growth (flexion stage) after the early hyperplastic growth. Effect of taurine on red sea bream larvae Y-S Kim et al.

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