Estimated average annual bycatch of loggerhead sea turtles (Caretta caretta) in U.S. Mid-Atlantic bottom otter trawl gear, 1996-2004

"During 1994-2004, fisheries observers documented interactions between bottom otter trawl gear and loggerhead (Caretta caretta), Kemp's ridley (Lepidochelys kempi) and leatherback (Dermochelys coriacea) turtles in the U.S. Mid-Atlantic region (i.e. south of 41°30'N/66°W to approximately 35°00'N/75°30'W). Most of these interactions were with loggerhead turtles, although Kemp's ridley and leatherback turtles were also observed in small numbers. Due to the low number of Kemp's ridley and leatherback interactions, bycatch rates and total mortality were only estimated for loggerhead turtles. Vessel Trip Reports (VTR) from fishermen operating bottom otter trawl gear in the Mid-Atlantic were used to expand predicted bycatch rates to total estimated bycatch. Due to reduced quality of VTR data in 1994 and 1995, bycatch is reported from 1996-2004 only. Significant factors affecting sea turtle bycatch were latitude zone, depth, sea surface temperature, and the use of a working Turtle Excluder Device (TED). A working TED is defined as one which is not clogged (e.g., with fish or debris). Predicted bycatch rates were stratified by the combination of significant variables. Estimated average annual bycatch of loggerhead turtles in Mid-Atlantic bottom otter trawl gear during 1996-2004 was 616 animals (C.V.=0.23, 95%C.I. over the 9 year period: 367-890)"--Document's home page. by Kimberley T. Murray. "September 2006." Includes bibliographical references.

1994年至2004年间，渔业观察员在美国中大西洋海域（即北纬41°30′、西经66°以南至约北纬35°00′、西经75°30′的范围）记录了底拖网（bottom otter trawl gear）与蠵龟（loggerhead, Caretta caretta）、肯氏丽龟（Kemp's ridley, Lepidochelys kempi）及棱皮龟（leatherback, Dermochelys coriacea）的兼捕交互事件。此类兼捕事件以蠵龟为主，虽也少量观测到肯氏丽龟与棱皮龟，但因后两者的兼捕记录量极少，研究仅针对蠵龟估算了兼捕率与总死亡量。研究采用在中大西洋海域作业的底拖网渔船的航行报告（Vessel Trip Reports, VTR），将预测的兼捕率外推得到总兼捕量估算值。鉴于1994年与1995年的VTR数据质量不佳，仅报告了1996年至2004年的兼捕相关数据。影响海龟兼捕的显著因素包括纬度带、作业水深、海表温度，以及是否使用正常运作的海龟排斥装置（Turtle Excluder Device, TED），其中正常运作的海龟排斥装置定义为未被堵塞（如被鱼类或杂物堵塞）的装置。研究基于上述显著影响变量的组合对预测兼捕率进行分层处理。1996年至2004年间，中大西洋海域底拖网作业中蠵龟的年均估计兼捕量为616只（变异系数C.V.=0.23，9年周期内95%置信区间：367~890）。本内容源自Kimberley T. Murray于2006年9月发布的文档主页，包含参考文献。