模拟捕食者风险对大黄鱼幼鱼行为、游泳能力及应激水平的影响

SIMULATED PREDATOR RISK ON BEHAVIOR, SWIMMING ABILITY AND STRESS RESPONSE OF JUVENILE LARGE YELLOW CROAKER (LARIMICHTHYS CROCEA)

  • 摘要: 许多研究表明适当强度的抄网追赶训练能够提高幼鱼感知风险的能力, 塑造出敏捷应对捕食者追赶的行为。大黄鱼生性敏感, 对外界刺激反应较为强烈, 抄网追赶训练能否提高其应对风险的能力尚未知。研究通过对大黄鱼(Larimichthys crocea)幼鱼(80 dpf)进行为期15d和30d, 每天2次, 每次分别0、2.5min、5.0min和7.5min的抄网追赶, 探究了大黄鱼幼鱼在不同水平的抄网追赶下生长、行为、游泳能力和应激水平的变化; 并且在30d刺激结束后的第8天, 再次给予抄网追赶刺激, 以测试停训后大黄鱼幼鱼再次面对刺激时应激水平的变化。结果表明: 不管是短期(15d), 还是较长期(30d)的刺激, 显著性检验表明不同水平的追赶训练对生长的影响不显著, 但效应量和贝叶斯因子表明, 30d的刺激效应更为明显。经过15d刺激后, 显著性检验及效应量都表明追赶刺激对大黄鱼幼鱼对陌生环境的探索能力无显著影响;刺激30d后, 显著性检验以及效应量均表明30 d的追赶刺激大黄鱼幼鱼对陌生环境探索能力的影响要比15d强。此外, 显著性检验、效应量及贝叶斯因子均表明一定水平的刺激能降低大黄鱼幼鱼的皮质醇水平。另外, 显著性检验表明15 d的追赶训练仅对绝对临界游泳速度(Ucrita)负面影响显著, 但效应量表明15d和30d的刺激对绝对(Ucrita)和相对临界游泳速度(Ucritr)负面效应都相当明显。同时, 显著性检验、效应量和贝叶斯因子都表明停训后第8天的大黄鱼幼鱼再次受到刺激时, 其应激水平明显低于未受过训练的个体。总体而言, 抄网刺激训练能有效提高人工养殖大黄鱼幼鱼的野外适应能力。研究结果为深入研究大黄鱼的行为及为大黄鱼放流前的驯化技术研发奠定了一定的基础。

     

    Abstract: Stock enhancement has been considered to be the most direct and effective measure to restore fishery resources. However, the outcomes are unsatisfactory as expected. The main reason is that hatchery-produced fishes for restocking can not adapt wild environment well after released. The most challenge that they would face is predation risk. Many studies had shown that net-chasing treatment can simulate predator risks and pose a survival threat to fish. Appropriate intensity net-chasing training could improve the ability of juvenile fishes to deal with risk and shape the behavioral abilities to escape from predators. The large yellow croaker (Larimichthys crocea) is sensitive to external stimulation, whether the net-chasing treatment could improve the escape ability for the species remains doubt. To verify the efficiency of net-chasing to shape the abilities of the large yellow croaker, herein we performed a net-chasing training experiment with the juveniles (80 dpf). Four chasing levels, 0, 2.5min, 5.0min and 7.5min, were applied for 15d and 30d twice daily, respectively. Then, growth, behavior (novel environment test, stress coping style test, emergence test and avoidance test), swimming ability, and stress response were measured. Moreover, at a 7d interval after the 30d training, the juveniles were performed another 10min net-chasing to investigate the changes of stress response. Results showed that either in the short term (15d) or long term (30d) treatment, significance analysis shows that different intensities of chase training did not result in a significant effect on growth, however, effect size and Bayes factor indicate that effect of 30d chase training is not negligible. On the behavior, after a 15d chase training, both significance analysis and effect size indicate that the chase training affected negatively on the exploration tendency of juvenile large yellow croaker. After a 30d chase training, significance analysis and effect size indicate that the exploration tendency of 30d stronger than 15d. On the stress response, significance analysis as well as effect size indicated that the cortisol level in juvenile large yellow croaker increased significantly after a chase training for 15d or 30d. On the swimming ability, significance analysis indicated that only Ucrita was reduced significantly after a 15d chasing training, and effect sizes indicated that both Ucrita and Ucritr were negatively affected highly after a 15d or 30d chase training. After a 7d interval post 30d training, significance analysis, effect size, and Bayes factor showed that cortisol level of the juveniles was significantly declined when they faced the net chasing again. In conclusion, the net chasing is probably an effective way to improve the ability of the hatchery-produced large yellow croaker for restocking to adapt the wild environments. The findings from the present study laid a certain foundation for training the large yellow croaker before release for stock enhancement.

     

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