Whale sightings during POLARSTERN cruise PS90 (ANT-XXX/3)

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 PS90 (Cape Town – Bremerhaven) 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，这是因为标准调查方法——线样带调查（line-transect surveys）的实施既极具挑战性，且成本高昂。为解决这一难题，我们启动了一项计划，通过值班航海官，将所有极星号（Polarstern）科考航次中偶遇的鲸类目击信息以电子方式记录下来。在极星号PS90航次（开普敦—不来梅港）期间，值班航海官通过安装在船舶驾驶台触摸屏笔记本电脑上的定制化软件套件（WALOG，WhAleLOGger），记录下了肉眼目视的偶遇目击信息。研究人员通过肉眼或手持双筒望远镜（7×50）对物种进行鉴定，尽可能划分至最细致的分类学层级，并为其赋予鉴定可信度等级。若条件允许，则对动物个体数量进行计数；对于大种群，则通过估算得到数量。若无法将物种鉴定至物种层级，则将其归类至可识别的下一级分类单元。目击位置、日期与时间信息会在记录时，从船舶DAVIS-Ship系统（https://dship.awi.de/）自动同步至WALOG软件。若条件允许，会拍摄照片用于回溯性分析。所有收集到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。为此，研究人员会对目击时间与位置的合理性、物种名称的标准化处理、目击时添加的备注信息，以及照片（若有）等额外信息进行核查，以验证或优化物种鉴定结果。本数据集可应用于物种分布建模，并可向相关方通报鲸类目击事件的发生情况。