Whale sightings during POLARSTERN cruise PS96 (ANT-XXXI/2)

Data on whale distribution and abundance in the polar oceans is rather sparse, as implementing the standard surveying method, line-transect surveys, is challenging and costly. To overcome this problem, we initiated a program to electronically log all opportunistic cetacean sightings during all Polarstern expeditions through the nautical officer on watch. Opportunistic (visual) sightings by naked eye were logged during Polarstern Cruise PS96 (Cape Town - Punta Arenas) by the nautical officer on duty using a customized Software package (WALOG, WhAleLOGger) installed on a touch screen laptop located on the ship's bridge. Species were identified by naked eye or handheld binoculars (7x50) to the lowest possible taxonomical level and assigned a “certainty” level of identification. The number of animals were counted if possible or estimated for larger groups. Whenever identification to species level was not possible, the next identifiable taxonomical category was assigned. Information on sighting position, date and time are automatically transferred from the ship's DAVIS-Ship System (https://dship.awi.de/) to the WALOG software at the time of logging. Photographs were taken if possible for retrospective analysis. All data of acquired sightings were retrospectively validated by a marine biologist and converted to a standard format. To this end, plausibility of sighting time, location, standardization of species names, eventual comments added at the time of sighting, as well as additional information such as photographs (if available) were checked either to verify or improve species identification. Datasets are used in species distribution modelling and to inform interested parties about occurrences.

极地海洋中鲸类的分布与丰度数据相当匮乏，因为标准调查方法——线样带调查（line-transect surveys）的实施兼具挑战性与高昂成本。为解决这一难题，我们启动了一项计划，通过值班航海官记录所有极星号（Polarstern）科考航次中偶遇的鲸类目视观测数据。在极星号（Polarstern）PS96航次（开普敦至蓬塔阿雷纳斯）期间，值班航海官借助安装在船舶驾驶台触摸屏笔记本电脑上的定制化软件包WALOG（WhAleLOGger，鲸类日志系统），完成了目视偶遇观测的记录工作。研究人员通过裸眼或手持7×50型双筒望远镜，将物种鉴定至尽可能低的分类学层级，并为其赋予对应鉴定置信等级。若条件允许则统计动物个体数量，针对大型群体则开展估算；若无法鉴定至物种层级，则指定下一级可识别的分类单元。目击位置、日期与时间信息会在记录生成时，自动从船舶DAVIS-Ship系统（https://dship.awi.de/）同步至WALOG软件。若现场条件允许，研究人员会拍摄照片用于回溯分析。所有获取的目击数据均由海洋生物学家进行回溯验证，并转换为标准格式。具体核查内容包括：目击时间与地点的合理性、物种名称的标准化、目击时添加的附加备注，以及照片（若有）等额外信息，以此确认或优化物种鉴定结果。本数据集可应用于物种分布建模，并可为相关方提供鲸类出现记录信息。