环境丰容对早期发育阶段许氏平鲉趋礁行为的影响

采用实验生态学方法,观测了不同环境丰容水平下培育的许氏平鲉(Sebastes schlegelii)仔、稚、幼鱼的趋礁行为反应,统计分析了两种结构模型礁对实验鱼的诱集效果,初步探究了环境丰容对实验鱼趋礁行为的影响。结果显示:许氏平鲉仔、稚、幼鱼具有明显不同的行为习性与趋礁行为特性,未放入模型礁前,稚鱼在水槽中分布较分散,仔、幼鱼则集中于水槽四周阴影区域,中央区域分布极少;放入模型礁后,仔、稚鱼在礁区的平均分布率无显著变化(P0.05);幼鱼则由1.11%分别增大至47.78%(塔型礁)和54.44%(管型礁)(P0.01),随着个体生长发育,其趋礁性显著增强。环境丰容25 d(即48日龄的稚鱼),对实验鱼群体重心与模型礁的平均距离D_(gr)、个体与模型礁的平均距离D_(fr)、个体间的平均距离D_(ff)及实验鱼在水槽中央区域(VI区)的平均分布率均无显著影响(P0.05)。环境丰容47 d(即70日龄的幼鱼),未放入模型礁前,高水平丰容组(EH组)幼鱼在VI区的平均分布率显著高于空白对照组(C组)(P0.05),低水平丰容组(EL组)与C组、EH组均无显著差异(P0.05),各处理组D_(gr)与D_(fr)大小顺序为:EL组C组EH组;放入模型礁后,各处理组幼鱼在模型礁区域(VI区)的平均分布率:EL组C组EH组,Dfr与Dff大小顺序为:EL组C组EH组;表明低水平环境丰容可有效增强许氏平鲉幼鱼的趋礁行为,减小幼鱼"胆量",这对于提高放流幼鱼在野外的存活率具有重要意义。旨在探讨环境丰容这一行为驯化手段,对于增强早期发育阶段许氏平鲉趋礁行为的可行性,为增殖放流苗种的高效健康培育及增殖型人工鱼礁的选型提供参考。

Effects of environmental enrichment on the distribution of Sebastes schlegelii in early developmental stages

The effects of three levels of environmental enrichment treatments (no environmental enrichment (group C); low-level environmental enrichment (group EL); and high-level environmental enrichment (group EH)) on the behavioral response and distribution of Sebastes schlegelii in early developmental stages were studied with an experimental ecology method. Additionally, the attractive effect of two kinds of artificial reef models (pyramid and cylinder reef models) on S. schlegelii was also studied. The results showed that S. schlegelii had different behavioral habits in early developmental stages. The post-larvae were scattered, whereas larvae and juveniles concentrated around the test tanks when there were no artificial reef models. When the two kinds of artificial reef models were introduced into the test tanks, there were no significant changes in the larval and post-larval average distribution rates in the central region of the tanks where the artificial reef models were placed (P>0.05), but juveniles increased significantly from 1.11% to 47.78% and 54.44%, for pyramid and cylinder reef models, respectively (P<0.01), indicating significantly increased attractive effects of the two kinds of models with the growth and development of the fish. Environmental enrichment of 25 days had no significant effects on the average distance between the center of gravity of colony and artificial reef models (D_gr), average distance of fish and the center of artificial reef models (D_fr), distance between individual fish (D_ff), nor average distribution rate in the central region (P>0.05). However, environmental enrichment of 47 days showed different behavioral characteristics among juvenile fish cultured in three types of net cage environments. When no reef models were introduced, the average distribution rate in the central region of group EH was significantly higher than that of group C (P<0.05). However, there were no significant differences between groups EL and C, nor between groups EL and EH (P>0.05). The order of D_gr and D_fr was group EL > C > EH. When artificial reef models were introduced into the tanks, the order of the average distribution rate in the central region was group EL > C > EH, and the order of D_fr and D_ff was group EL < C < EH. These results indicated that low-level environmental enrichment could strengthen the juvenile attractive effect of artificial reef models and decrease the boldness of fish, which is essential for their survival in the natural environment. The research may provide referential information for further studies in hatchery techniques and stock enhancement.