Griffing Denise, Larson Shawn, Hollander Joel, Carpenter Tim, Christiansen Jeff, Doss Charles
Life Sciences, Seattle Aquarium, Seattle, Washington, United States of America.
Department of Statistics, University of Washington, Seattle, Washington, United States of America.
PLoS One. 2014 Jan 27;9(1):e87081. doi: 10.1371/journal.pone.0087081. eCollection 2014.
The bluntnose sixgill shark, Hexanchus griseus, is a widely distributed but poorly understood large, apex predator. Anecdotal reports of diver-shark encounters in the late 1990's and early 2000's in the Pacific Northwest stimulated interest in the normally deep-dwelling shark and its presence in the shallow waters of Puget Sound. Analysis of underwater video documenting sharks at the Seattle Aquarium's sixgill research site in Elliott Bay and mark-resight techniques were used to answer research questions about abundance and seasonality. Seasonal changes in relative abundance in Puget Sound from 2003-2005 are reported here. At the Seattle Aquarium study site, 45 sixgills were tagged with modified Floy visual marker tags, along with an estimated 197 observations of untagged sharks plus 31 returning tagged sharks, for a total of 273 sixgill observations recorded. A mark-resight statistical model based on analysis of underwater video estimated a range of abundance from a high of 98 sharks seen in July of 2004 to a low of 32 sharks seen in March of 2004. Both analyses found sixgills significantly more abundant in the summer months at the Seattle Aquarium's research station.
太平洋睡鲨（Hexanchus griseus）是一种分布广泛但鲜为人知的大型顶级掠食者。20世纪90年代末和21世纪初在太平洋西北部潜水者与鲨鱼相遇的轶事报道激发了人们对这种通常生活在深海的鲨鱼及其在普吉特海湾浅水区出现情况的兴趣。通过分析西雅图水族馆在埃利奥特湾的六鳃鲨研究地点的水下视频记录以及标记重捕技术来回答有关数量和季节性的研究问题。本文报告了2003年至2005年普吉特海湾相对数量的季节性变化。在西雅图水族馆的研究地点，45条六鳃鲨被标记上改良的Floy可视标记标签，另外估计有197次未标记鲨鱼的观测记录以及31条返回的标记鲨鱼，总共记录了273次六鳃鲨观测。基于水下视频分析的标记重捕统计模型估计数量范围从2004年7月观测到的最多98条鲨鱼到2004年3月观测到的最少32条鲨鱼。两项分析均发现，在西雅图水族馆的研究站，夏季六鳃鲨的数量明显更多。
