Effects of α-tocopheryl acetate supplementation in preslaughter diet on antioxidant enzyme activities and fillet quality of commercial-size Sparus macrocephalus

This study examined the effects of dietary α-tocopheryl acetate supplementation on antioxidant enzyme activities and fillet quality in commercial-size Sparus macrocephalus. Three hundred fish [main initial weight （350±12） g] were divided into three groups （E250, E500 and El000） and reared in 9 cages. The fish were fed for 8 weeks with three diets containing different levels of dietary α-tocopheryl acetate （289, 553, 1069 mg/kg）. Over the experimental period, fish were fed to satiation and reached a final mean weight of （465±28） g without significant body weight difference and proximate composition difference. Fillet α-tocopherol was significantly （P〈0.05） different between groups, reaching levels of 14.2, 22.1, 30.9 pg/mg fillet for groups E250, E500 and El000, respectively. Total serum superoxide dismutase （SOD） activity increased significantly （P〈0.05） in fish fed the diets high in α-tocopheryl acetate, but serum glutathione peroxidase （GPX） activity was unaffected. In storage on ice, fillets of fish fed the diets high in α-tocopheryl acetate exhibited significantly lower （P〈0.05） levels of oxidation. These results suggested that increased dietary α-tocopheryl acetate could increase its flesh deposition, increase the activity of SOD and prevent lipid peroxidation ofSparus macrocephalus fillets in retail storage on ice.

Influence of fasting on muscle composition and antioxidant defenses of market-size Sparus macrocephalus

The study was conducted to investigate fasting effects on flesh composition and antioxidant defenses of market-size Sparus macrocephalus. Two hundred fish (main initial weight 580 g) were divided into two groups (control and fasted) and reared in 6 cages. After two weeks of adaptation, group I fasted for 28 d; group II was fed normally as a control. In 3, 7, 14, 21 and 28 d, 6 fish per group were sampled for proximate flesh composition, liver antioxidant enzyme activities and malondialdehyde flesh content analyses. In fasted fish, the reduction of lipid content in muscle occurred after day 3, and, compared to controls, the content of protein decreased from day 14, the activities of liver antioxidative enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPX) increased from day 3, and flesh malondialdehyde levels increased from day 21. Flesh fat reduction shows that fasting may be used as a technique to reduce flesh lipid content in Sparus macrocephalus. However, considering flesh protein loss and the subsequent oxidative stress, the fasting technique should be used with precautions.

Effect of n-3 HUFA levels in rotifers and Artemia on growth and survival of larval black sea bream (Sparus macrocephalus)

Requirement for dietary n-3 HUFA (n-3 highly unsaturated fatty acid) for growth and survival of black sea bream (Sparus macrocephalus) larvae was studied using rotifers and Artemia at various levels of n-3 HUFA. Five treatments with rotifers and Artemia differing in n-3 HUFA were prepared by enriching them with various oil emulsions. Results indicated that dietary n-3 HUFA significantly influence fish n-3 HUFA levels and are essential for growth and survival of black sea bream larvae. The results also indicated that the incorporation of n-3HUFA TG (triacylglycerols) into tissues of larval black sea bream was more effective from natural fish oil in comparison with n-3 HUFA fatty acid ethyl esters from ethyl-esterified oil.

Effectiveness of stocking Sparus macrocephalus fry in situ in the East China Sea

The sea area surrounding Baishishan Island has abundant fishery resources because of its plentiful food and rocky reefs that provide refuge from predators.However,overfishing has occurred in many areas and some species’local populations need to be replenished through stocking programs.This case study,using Sparus microcephalus as the test species,designed and analyzed detailed stocking strategies to improve the survival ratio and control the active range of the released fishes.Controlled variables included release location,release time,and tidal level.Two stocking strategies were designed,executed,and evaluated for comparison.A traditional stocking method was applied to the high flow area of Baishishan Island in Xiangshan Bay,East China Sea.The released fry were transported by boat and released to the sea using buckets.Released fish were traced using plastic tags.The average distance of the 19 recaptured fry from the release point was 7.6 km with 52.9%mortality rate.The distance at recapture and mortality rate among recaptured individuals showed that the traditional releasing method was not successful.An in situ stocking method was used in a low tide area and natural process was imitated to decrease the stress response and promote physiological adaptation.The purpose of this method was to prolong the release process applying temporary net cages at the release location,which resulted in a regional distribution of the released fish and possibly improving the food availability.A new Sr+tagging technique was adopted to evaluate the release effect and quantify comparative release data.Only 1 fish among the 354 caught was found farther than 1 km from the release point in the following 6 months.The results validated the promotion of the new stocking technique.

余氯对大亚湾海区平鲷和黑鲷幼鱼的毒性研究

用含游离余氯、化合余氯的海水分别对大亚湾平鲷Rhabdosargussarba、黑鲷Sparusmacrocephalus浸毒处理30min和60min。结果表明，两种形态余氛对色的耗氧率有明显抑制作用，游离余氯对平鲷、黑鲷的48hLC50分别为0．19和0．18mg·L－1，48hLC1分别为0．07和0.06mg·L－1；化合余氯的48hLC50分别为0.56和0．60mg·L－1，48hLC1分别为0．21和0．24mg·L-1。游离余氯的毒性大约是化合余筑的6倍。游离余氯、化合余氯安全阈限估算值分别为0．09和0．28mg·L－1，稍高于48hLC1。