Cetacean observations and survey effort during the TEMPO voyage (Jan-Mar 2021)

This metadata record describes cetacean line-transect distance sampling dataset collected during the 2021 TEMPO (Trends in Euphausiids off Mawson, Predators, and Oceanography) voyage onboard the RV Investigator. The primary goal of TEMPO was to collect data to estimate krill biomass with a view to update the precautionary catch limit for krill in CCAMLR’s Division 58.4.2-East. The survey was also designed to improve our understanding on the connectivity of the krill population, and overlap between krill and predators. The survey consisted of six major acoustic line-transects to estimate krill biomass and to observe swarm behaviour across ecological and density gradients within the survey area south of 62°S between 55° and 80° E, and a single fine-scale krill box acoustic survey off the Mawson coast. Comprehensive oceanographic (CTDS, XBTs ARGSO floats) and biological (plankton) sampling were also conducted to understand the habitat environment of krill and its predators. Predator observation was undertaken throughout the voyage to improve our understanding on the connectivity of the krill population, and overlap of distribution between krill and predators. The information gathered contributes to the design of tractable and sustainable long-term monitoring plan and to evaluate spatial management of the krill fishery.A team of four dedicated cetacean observers (with contributions from other experienced staff onboard) undertook formal line transect distance sampling when conditions allowed. Two observers were on effort during line transect effort; they were stationed in protective boxes on the forward Deck 05 of the RV Investigator. A data entry person was situated on the bridge; sighting, effort and weather data were logged using PAMGUARD (Pamguard Development Team 2021). The two observers scanned port and starboard, respectively, from abeam (~90° from the ship’s heading) through to around ~10° beyond the trackline on the other side. (i.e., this is single platform sighting data, sensu Burt et al. 2014). They searched using a combination of naked eye, Fujinon 7 x 50 FMTRC-SX binoculars and Fujinon 25 x 150 MT binoculars. Radial distances were estimated using the reticles of the 7 x 50 binoculars, or were estimated when detections were too close, or if the horizon was not available. Reticle information can be used to estimate radial distance to the observation using the methods outlined in Kinzey et al. (2000) and Kinzey and Gerrodette (2001). On Deck 05, average observer eye-height was ~18.4 m above the water line; the average observer eye-height on the bridge was ~20.7m. The observers maintained line transect search effort during daylight hours, with a sea state ≤ 6, and with reasonable visibility. For shorter periods of poorer visibility (or ship operations which slowed the vessel considerably or altered travel direction) they maintained ‘visual search’ effort on Deck 05, or moved to the bridge to undertake ‘bridge only’ searching during extended periods of poor weather and/or ship operations.A total of 3612 km of line transect distance sampling effort for cetaceans was achieved both within the TEMPO survey area and during the transit periods, in addition to 153 km of informal sighting effort from Deck 05, and another 1115 km of bridge only effort. This combined effort yielding 621 sightings of approximately 1609 animals. The most prevalent species observed was humpback whales, followed by fin whales.Sightings may include non-cetacean species like seabirds and pinnipeds, but as these were not the target taxa for this observation process, consistent recording of sighting for these should not be assumed. ReferencesBurt, M. L., Borchers, D. L., Jenkins, K. J., and Marques, T. A. (2014). Using mark-recapture distance sampling methods on line transect surveys. Methods in Ecology and Evolution, 5(11), 1180-1191. doi:10.1111/2041-210x.12294Kinzey D, Olson P, Gerrodette T. 2000. Marine mammal data collection procedures on research ship line-transect surveys by the Southwest Fisheries Science Center. Southwest Fisheries Science Center, Administrative Report LJ-00-08.Kinzey, D., and Gerrodette, T. (2001). Conversion factors for binocular reticles. Marine Mammal Science, 17, 353-361.Pamguard Development Team (2021). Pamguard. Version 2.02.01, Available at: http://www.pamguard.org/.

本元数据记录描述的是2021年搭载“调查者号”（RV Investigator）执行的TEMPO（Trends in Euphausiids off Mawson, Predators, and Oceanography，莫森海域磷虾、捕食者与海洋学趋势）航次所采集的鲸类线迹距离采样数据集。TEMPO科考的核心目标是采集数据以估算磷虾生物量，进而更新南极海洋生物资源养护委员会（Commission for the Conservation of Antarctic Marine Living Resources, CCAMLR）58.4.2-East分区的磷虾预防性捕捞限额。本调查同时旨在深化对磷虾种群连通性，以及磷虾与捕食者分布重叠情况的认知。本次调查包含6条主要声学线迹样带，用于估算62°S以南、55°E至80°E调查区域内的磷虾生物量，并观测该区域生态梯度与密度梯度下的磷虾群聚行为；此外还在莫森海岸外开展了1次精细尺度磷虾箱式声学调查。为探明磷虾及其捕食者的栖息环境，本次调查同步开展了综合海洋学（CTDS、XBT、ARGSO浮标）与生物学（浮游生物）采样工作。整个航次全程开展捕食者观测，以进一步明晰磷虾种群连通性与二者分布重叠格局。所采集的信息将为制定可行且可持续的长期监测计划，以及评估磷虾渔业的空间管理方案提供支撑。

本次鲸类观测由4名专职观察员（另有船上其他资深工作人员协助）负责，仅在海况适宜时开展标准化线迹距离采样作业。线迹采样作业期间，2名观察员分别值守于“调查者号”05层前甲板的防护观察箱内，分别负责左舷与右舷观测。另有1名数据录入员位于舰桥，通过PAMGUARD（Pamguard Development Team 2021）软件记录目击、观测作业与气象数据。两位观察员分别扫描左舷与右舷，观测范围从正横方向（与船舶航向呈约90°）延伸至另一侧航迹线外约10°范围，即本数据属于单平台目击数据，遵循Burt等人2014年的定义。观测手段包括裸眼目视、富士农7×50 FMTRC-SX双筒望远镜与富士农25×150 MT双筒望远镜。径向距离可通过7×50双筒望远镜的分划板估算，若观测目标过近或无法看清地平线时亦可采用估算方式。分划板测距方法可参考Kinzey等（2000）与Kinzey及Gerrodette（2001）所述的操作规范。05层前甲板的观察员平均眼高距水面约18.4米，舰桥观察员的平均眼高约20.7米。观察员仅在日间、海况等级≤6且能见度良好的时段开展线迹搜索作业；在短时能见度不佳（或船舶作业大幅减速、改变航向）时，仍于05层甲板维持目视搜索，若遭遇长时间恶劣天气或船舶作业，则转移至舰桥开展“仅舰桥”模式的观测。

本次航次在TEMPO调查区域与航渡阶段共计完成3612千米的鲸类线迹距离采样作业，此外05层甲板还完成了153千米的非正式目击作业，舰桥单独作业里程达1115千米。上述总作业量共计记录到621次目击事件，涉及约1609头动物。观测到的优势物种为座头鲸，其次为长须鲸。需注意的是，目击记录可能包含海鸟、鳍足类等非鲸类物种，但由于这些并非本次观测的目标类群，因此不能默认会对其进行标准化记录。

参考文献
Burt, M. L., Borchers, D. L., Jenkins, K. J., & Marques, T. A. (2014). 线迹调查中的标记-重捕距离采样方法应用. 生态学与进化方法, 5(11), 1180-1191. doi:10.1111/2041-210x.12294
Kinzey, D., Olson, P., & Gerrodette, T. (2000). 西南渔业科学中心船舶线迹调查的海洋哺乳动物数据采集规程. 西南渔业科学中心, 行政报告LJ-00-08
Kinzey, D., & Gerrodette, T. (2001). 双筒望远镜分划板换算系数. 海洋哺乳动物科学, 17, 353-361
Pamguard开发团队 (2021). Pamguard. 版本2.02.01, 可获取于: http://www.pamguard.org/