Whale sightings during POLARSTERN cruise ANT-XXVIII/4

From 13 March to 09 April 2012 Germany conducted a fisheries survey on board RV Polarstern in the Scotia Sea (Elephant Island - South Shetland Island - Joinville Island area) under the auspices of CCAMLR. During this expedition, ANT-XXVIII/4, an opportunistic marine mammal survey was carried out. Data were collected for 26 days along the externally preset cruise track, resulting in 295 hrs on effort. Within the study area 248 sightings were collected, including three different species of baleen whales (fin whale (Balaenoptera physalus), humpback whale (Megaptera novaeangliae), and Antarctic minke whale (Balaenoptera bonaerensis) and one toothed whale species, killer whale (Orcinus orca). More than 62% of the sightings recorded were fin whales (155 sightings) which were mainly related to the Elephant Island area (116 sightings). Usual group sizes of the total fin whale sightings ranged from one to five individuals, also including young animals associated with adults during some encounters. Larger groups of more than 20 whales, and on two occasions more than 100 indivuduals, were observed as well. These large pods of fin whales were observed feeding in shallow waters (< 300 m) on the north-western shelf off Elephant Island, concordant with large aggregations of Antarctic krill (Euphausia superba). This observation suggests that Elephant Island constitutes an important feeding area for fin whales in early austral fall, with possible implications regarding the regulation of (krill) fisheries in this area.2012年3月13日至4月9日，德国在斯科舍海（象岛-南设得兰群岛-乔纳森岛海域）搭载“极星号”科考船（RV Polarstern）开展渔业调查，本次调查由南极海洋生物资源养护委员会（CCAMLR）牵头实施。本次科考航次编号为ANT-XXVIII/4，期间同步开展了机会主义海洋哺乳动物调查。科考团队沿预先设定的巡航航线累计作业26天，有效观测时长共计295小时，在研究区域内共记录到248次鲸类目击事件，涉及4个鲸类物种：3种须鲸——长须鲸（Balaenoptera physalus）、座头鲸（Megaptera novaeangliae）、南极小须鲸（Balaenoptera bonaerensis），以及1种齿鲸——虎鲸（Orcinus orca）。其中长须鲸目击次数占比超62%（共155次），且主要集中在象岛海域（116次）。长须鲸的常规种群规模为1至5头，部分目击事件中还记录到幼崽伴随成年个体的群体；此外也观测到超过20头的大型种群，且有2次观测到100头以上的超大鲸群。这些大型长须鲸群聚集在象岛西北陆架的浅水区（水深<300米）觅食，此时该区域恰好存在大量南极磷虾（Euphausia superba）聚集。本次观测表明，南大洋初秋时节，象岛是长须鲸重要的觅食栖息地，该发现可为该区域磷虾渔业的管理调控提供参考依据。