Effect of stocking density on growth, digestive enzyme activity and cortisol level in larvae and juveniles of Japanese flounder, Paralichthys olivaceus
Effect of stocking density on growth, digestive enzyme activity and cortisol level in larvae and juveniles of Japanese flounder, Paralichthys olivaceus
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DOI：
10.1016/j.aquaculture.2006.05.021
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发表时间：
2006-09-08
期刊：
影响因子：
4.5
通讯作者：
Tanaka, Masaru
中科院分区：
文献类型：
--
作者：
Bolasina, Sergio;Tagawa, Masatomo;Tanaka, Masaru
研究放养密度对牙鲆幼体（2 ~ 35 DAH）和幼体（46 ~ 65 DAH）生长、消化酶活性和皮质醇水平的影响。记录体重和体长，检测0.1% MS 222麻醉后冷冻标本的酶活性（胰蛋白酶和脂肪酶）和皮质醇水平。第一次试验采用两种不同密度的幼虫（1000和5000个体，3个1001箱）进行试验。15 DAH后，低密度组的体重和总长度显著大于高密度组（P < 0.05）。30 DAH前各组皮质醇浓度差异无统计学意义（P < 0.05）， 35 DAH时高密度组皮质醇浓度显著升高（P < 0.05）。消化酶活性差异无统计学意义（P < 0.05）。试验2将46尾DAH稚鱼按2种不同密度（200尾和2000尾，100尾箱，底面面积0.22 m(2)）饲养在100尾箱中，饲养15 d。底栖鱼和游栖鱼分别取样。61 DAH时，在高密度池中选择性捕获游动鱼，将100尾转移到30 1个池中饲养4 d。游动比目鱼幼鱼的体长和体重长势显著低于定居鱼（P < 0.05）。在61 DAH时，高密度底沉鱼的总长度生长显著高于低密度底沉鱼（P < 0.05）。从高密度池中转移的游鱼，在转移4 d后体重显著增加（P < 0.05）。移植鱼的总长度在这段时间内也有所增加，但差异不显著（P < 0.05）。幼鱼中胰蛋白酶比活性显著高于高密度组底沉鱼（P < 0.05）。转低密度后2 d胰蛋白酶水平显著降低（P < 0.05）。高密度饲养的游鱼皮质醇水平最高。高密度组底沉鱼的皮质醇水平高于低密度组。从高密度转向低密度的游鱼，4天后皮质醇水平有下降的趋势。结果表明，饲养密度对牙鲆幼鱼的生长发育有显著的影响，高密度会导致牙鲆幼鱼的社会等级（底栖>游泳），进而导致低等级个体皮质醇水平升高，生长速率降低。(c) 2006 Elsevier B.V.版权所有
The aim of this work was to evaluate the effect of stocking density on growth, digestive enzyme activity and cortisol level in larvae (2-35 DAH) and juveniles (46-65 DAH) of Japanese flounder. The body weight and body length were recorded, enzyme activities (trypsin and lipase) and cortisol levels were examined from frozen samples anesthetized with 0.1% MS 222.In the first experiment using larvae, two different densities (1000 and 5000 individuals in triplicate 100 1 tanks) were examined. The weight and total length of the low density group was significantly larger (P < 0.05) than that of high density group after 15 DAH. No significant differences (P > 0.05) were found in cortisol concentrations before 30 DAH, while a significantly higher concentration (P < 0.05) was found in the high density group on 35 DAR No differences were found in digestive enzyme activity.In the second experiment, juveniles of 46 DAH were kept in 100 1 triplicate Links at two different densities (200 and 2000 larvae in 100 1 tanks, bottom area 0.22 m(2)), and reared for 15 days. Bottom settled fish and swimming fish were separately sampled. On 61 DAH, the fish swimming were selectively captured in the high density tanks and 100 individuals were transferred to 30 1 tanks and further reared for 4 days. The growth in total length and weight of swimming juvenile flounder was significantly lower (P < 0.05) comparing with settled fish. Growth in total length at 61 DAH was significantly higher (P < 0.05) in the high density bottom settled fish, compared with the low density one. swimming fish transferred from high density tanks, showed a significant increase (P < 0.05) in body weight 4 days after the transfer. Transferred fish also showed an increase in total length during this period but this difference was not significant (P > 0.05).In juveniles, specific activity of trypsin was significantly higher (P < 0.05) in the swimming fish than the bottom settled in the high density group. Trypsin level was significantly lower (P < 0.05) after two days of being transferred to lower densities. Swimming fish reared at high density presented the highest cortisol levels. Bottom settled fish in the high density group had higher levels than those in the lower density On swimming fish transferred from high density to low density, cortisol levels tended to decrease after 4 days.These results showed that the rearing density has a significant influence on Japanese flounder juveniles, and results in social hierarchy (bottom settled > swimming) at high densities, that further causes higher cortisol levels and lower growth rates in low rank individuals. (c) 2006 Elsevier B.V. All rights reserved.