Behavioural patterns of a Tiger Shark (<i>Galeocerdo cuvier</i>) feeding aggregation at a blue whale carcass in Prony Bay, New Caledonia

Tiger Sharks, <i>Galeocerdo cuvier</i>, are large top-level predators usually solitary as adults. Observation of their scavenging activity on the carcass of a dead whale offered a rare opportunity for better understanding the pattern of intra-specific behaviour within the aggregations of these large predators. In January 2002, the stranding, subsequent death and consumption of a 17.4 m total length (TL) blue whale, <i>Balaenoptera musculus</i>, was observed and filmed in Prony Bay, southern New Caledonia. After three weeks of confinement in the bay, the cetacean was killed by adult bullsharks <i>Carcharhinus leucas</i>. The first adult Tiger Shark was subsequently observed around the carcass after 36 h. The fat slicks from the carcass attracted further Tiger Sharks which arrived after an additional 24 h. The use of photo-identification on video footage collected during four observation sessions over an eight-day period identified 46 individual Tiger Sharks (primarily adult females between 3.3 and 4 m TL) participating in the feeding aggregation. Only four animals were identified in two seperate observation sessions (over two consecutive days), suggesting a short-term residency pattern of several hours (&lt;36 h) around the carcass. As the arrival time of Tiger Sharks to the carcass differed, most arrivals of a new participant were followed by a frenzied period of intense intra-specific interaction. Different biting and agonistic behaviours were demonstrated by the Tiger Sharks on the carcass, including three new behaviours previously undescribed for this species. Size and level of aggressiveness appeared to be the determining factors of dominance amongst Tiger Sharks. These observations and analysis demonstrate that systematic study of feeding aggregations supported by photo-identification could contribute to knowledge of large shark ecology when coupled with capture-recapture, genetic fingerprinting and tagging techniques. Clip 1 - Feeding frenzy

鼬鲨（Tiger Shark，*Galeocerdo cuvier*）是大型顶级捕食者，成年个体通常独居。对其在死鲸尸体上的食腐行为开展观察，为深入理解这类大型捕食者聚集群体内的种内行为模式提供了难得的契机。2002年1月，研究人员在新喀里多尼亚南部的普龙尼湾观察并拍摄到一头总长17.4米的蓝鲸（*Balaenoptera musculus*）搁浅、随后死亡并被啃食的全过程。该蓝鲸在海湾内滞留三周后，被成年公牛鲨（*Carcharhinus leucas*）击杀。36小时后，首头成年鼬鲨首次现身该鲸尸周边。鲸尸释放的油脂浮膜进一步吸引了更多鼬鲨，这批新个体在额外24小时后抵达现场。通过对为期8天的4次观察场次采集的视频素材进行照片识别（photo-identification），共确认46头独立个体的鼬鲨（主要为体长3.3至4米的成年雌性）参与了此次进食聚集活动。仅有4头个体在两次独立的观察场次（间隔连续两天）中被识别到，这表明它们在鲸尸周边的停留时长仅为数小时（不足36小时），呈现出短期驻留的行为模式。由于鼬鲨抵达鲸尸的时间存在差异，绝大多数新个体抵达后，都会伴随一段激烈的种内互动狂乱阶段。鼬鲨在鲸尸上表现出多种啃咬与争斗行为，其中包含3种此前未被该物种记录的全新行为。体型与攻击性等级似乎是决定鼬鲨群体内优势地位的核心因素。上述观察与分析表明，若将照片识别法与标记重捕法、基因指纹分析及标记技术相结合，针对进食聚集群体开展的系统性研究，能够为大型鲨鱼生态学研究提供新的认知补充。片段1——进食狂乱