Australian Institute of Marine Science, Perth, Western Australia, Australia.
PLoS One. 2013 Apr 10;8(4):e60331. doi: 10.1371/journal.pone.0060331. Print 2013.
We used acoustic telemetry to describe the patterns of vertical movement, site fidelity and residency of grey reef sharks (Carcharhinus amblyrhynchos) on the outer slope of coral reefs in Palau, Micronesia, over a period of two years and nine months. We tagged 39 sharks (mostly adult females) of which 31 were detected regularly throughout the study. Sharks displayed strong inter-annual residency with greater attendance at monitored sites during summer than winter months. More individuals were detected during the day than at night. Mean depths of tagged sharks increased from 35 m in winter to 60 m in spring following an increase in water temperature at 60 m, with maximum mean depths attained when water temperatures at 60 m stabilised around 29°C. Sharks descended to greater depths and used a wider range of depths around the time of the full moon. There were also crepuscular cycles in mean depth, with sharks moving into shallower waters at dawn and dusk each day. We suggest that daily, lunar and seasonal cycles in vertical movement and residency are strategies for optimising both energetic budgets and foraging behaviour. Cyclical patterns of movement in response to environmental variables might affect the susceptibility of reef sharks to fishing, a consideration that should be taken into account in the implementation of conservation strategies.
我们使用声学遥测技术描述了在密克罗尼西亚帕劳外珊瑚礁斜坡上，两年零九个月期间灰礁鲨（Carcharhinus amblyrhynchos）的垂直移动模式、栖息地选择和居留情况。我们对 39 条鲨鱼（主要是成年雌性）进行了标记，其中 31 条在整个研究过程中定期被检测到。鲨鱼表现出强烈的年度居留性，夏季在监测点的出现频率高于冬季。白天比夜间检测到的个体更多。标记鲨鱼的平均深度从冬季的 35 米增加到春季的 60 米，这是由于 60 米处水温升高所致，当 60 米处水温稳定在 29°C 左右时，平均深度达到最大值。鲨鱼在满月前后会下潜到更深的水域，并在周围水域使用更广泛的深度范围。平均深度也存在昼夜节律，鲨鱼每天在黎明和黄昏时会游向较浅的水域。我们认为，垂直移动和居留的日、月和季节性循环是优化能量预算和觅食行为的策略。对环境变量的周期性运动模式可能会影响到礁鲨对捕捞的易感性，在实施保护策略时应考虑到这一点。
