Mattern Thomas, Ellenberg Ursula, Houston David M, Lamare Miles, Davis Lloyd S, van Heezik Yolanda, Seddon Philip J
Department of Zoology, University of Otago, Dunedin, New Zealand.
Department of Conservation, Science and Capability, Auckland, New Zealand.
PLoS One. 2013 Dec 18;8(12):e84381. doi: 10.1371/journal.pone.0084381. eCollection 2013.
Free-ranging marine predators rarely search for prey along straight lines because dynamic ocean processes usually require complex search strategies. If linear movement patterns occur they are usually associated with travelling events or migratory behaviour. However, recent fine scale tracking of flying seabirds has revealed straight-line movements while birds followed fishing vessels. Unlike flying seabirds, penguins are not known to target and follow fishing vessels. Yet yellow-eyed penguins from New Zealand often exhibit directed movement patterns while searching for prey at the seafloor, a behaviour that seems to contradict common movement ecology theories. While deploying GPS dive loggers on yellow-eyed penguins from the Otago Peninsula we found that the birds frequently followed straight lines for several kilometres with little horizontal deviation. In several cases individuals swam up and down the same line, while some of the lines were followed by more than one individual. Using a remote operated vehicle (ROV) we found a highly visible furrow on the seafloor most likely caused by an otter board of a demersal fish trawl, which ran in a straight line exactly matching the trajectory of a recent line identified from penguin tracks. We noted high abundances of benthic scavengers associated with fisheries-related bottom disturbance. While our data demonstrate the acute way-finding capabilities of benthic foraging yellow-eyed penguins, they also highlight how hidden cascading effects of coastal fisheries may alter behaviour and potentially even population dynamics of marine predators, an often overlooked fact in the examination of fisheries' impacts.
自由放养的海洋捕食者很少沿直线搜寻猎物，因为动态的海洋过程通常需要复杂的搜寻策略。如果出现直线运动模式，它们通常与迁徙活动或洄游行为有关。然而，最近对飞行海鸟的精细尺度追踪发现，当鸟类跟随渔船时会出现直线运动。与飞行海鸟不同，企鹅并不以渔船为目标并跟随它们。然而，来自新西兰的黄眼企鹅在海底觅食时经常表现出定向运动模式，这种行为似乎与常见的运动生态学理论相矛盾。在给奥塔哥半岛的黄眼企鹅部署GPS潜水记录器时，我们发现这些鸟经常沿着直线游动数公里，水平偏差很小。在几个案例中，个体在同一条线上上下游动，而有些线有不止一只企鹅跟随。使用遥控潜水器（ROV），我们在海底发现了一条非常明显的沟痕，很可能是由底拖网的一个拖网板造成的，它呈直线延伸，与最近从企鹅踪迹中确定的一条线的轨迹完全吻合。我们注意到与渔业相关的海底扰动区域有大量底栖 scavengers。虽然我们的数据证明了底栖觅食的黄眼企鹅具有敏锐的导航能力，但它们也凸显了沿海渔业隐藏的连锁效应如何可能改变海洋捕食者的行为，甚至可能改变其种群动态，这在审视渔业影响时往往是一个被忽视的事实。
