NMML Bering Sea Cetacean Survey 1999

Original provider: National Marine Mammal Laboratory Dataset credits: National Marine Mammal Laboratory Abstract: Visual line-transect surveys for cetaceans were conducted in the central-eastern Bering Sea (CEBS) from 5 July to 5 August 1999, in association with a pollock stock assessment survey aboard the NOAA ship Miller Freeman. Observers scanned for cetaceans with 25x (Big Eye) binoculars form the flying bridge (platform height = 12 m) at survey speeds of 18.5-22 km h-1 (10-12 knots). Transect survey effort was 1,761 km, in a study area 196,885 km2. An additional 609 km of trackline was surveyed, while in transit to or from Pollock survey way points. Fin whales (<i>Balaeoptera physalus</i>) were the most common large whale, and Dall's porpoises (<i>Phocoenoides dalli</i>) were the most common small cetacean. In the CEBS 1999, uncorrected cetacean abundance estimates were: 3,368 (CV = 0.29) fin whales, 810 (CV = 0.36) minke whales (<i>B. acutorostrata</i>), 14,312 (CV = 0.26) Dall's porpoise, and 693 (CV = 0.53) harbor porpoise (<i>Phocoena phocoena</i>). Non-pollock echosigns observed near cetaceans, some of which may have been cetacean prey, were not routinely identified during trawl sampling because the research focus was on pollock abundance assessment. Clearly, additional surveys and concomitant assessment of cetacean prey are needed to better define their role in the Bering Sea ecosystem. Such surveys, combined with measures of local hydrography and prey field should be the goal of future cetacean assessments.原始提供方：国家海洋哺乳动物实验室（National Marine Mammal Laboratory） 数据集归属：国家海洋哺乳动物实验室（National Marine Mammal Laboratory） 摘要： 1999年7月5日至8月5日，研究团队依托美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration，简称NOAA）所属的"米勒·弗里曼号"（Miller Freeman）调查船，在开展狭鳕种群评估调查的同时，于白令海中部偏东海域（Central-Eastern Bering Sea，下文简称CEBS）完成了鲸类目视样线调查。观测人员在飞行甲板（平台高度12米）上使用25倍（大眼牌Big Eye）双筒望远镜扫描观测鲸类，调查航速设定为18.5~22千米/小时（10~12节）。本次有效样线调查总航程为1761千米，研究区域面积达196885平方千米。此外，在往返狭鳕调查航点的航行过程中，额外完成了609千米的跟踪航线调查。 长须鲸（*Balaenoptera physalus*，原文拼写疑似笔误，原记录为Balaeoptera）为该区域最常见的大型鲸类，达氏鼠海豚（*Phocoenoides dalli*）则是最常见的小型鲸类。1999年CEBS海域的鲸类丰度未经校正估算结果如下：长须鲸3368头（变异系数CV=0.29）、小须鲸（*B. acutorostrata*）810头（CV=0.36）、达氏鼠海豚14312头（CV=0.26）以及港湾鼠海豚（*Phocoena phocoena*）693头（CV=0.53）。 在鲸类附近观测到的非狭鳕回声信号中，部分可能为鲸类的猎物，但由于本次研究核心聚焦于狭鳕丰度评估，拖网采样过程中未对上述信号开展常规鉴定。显然，为明确鲸类在白令海生态系统中的功能角色，需开展额外调查并同步对鲸类猎物进行评估。未来鲸类评估工作应结合此类调查、局地水文测量数据以及猎物分布场信息。