The Antarctic Peninsula (AP) is rapidly warming and empirical data on abundance trends of marine organisms are required to understand the impact of these physical changes, and interacting anthropogenic impacts, on the ecosystem. Recent estimates inferred increasing abundance of Type A killer whales at the top of this food chain, and here we provide new data on the abundance of Type B1 and B2 killer whales using photographic mark-recaptures collected during austral summers from 2008/2009 to 2017/2018. Both ecotypes were regularly photographed around the AP coastline, particularly off the west side, and individuals of both showed site fidelity across years. B1s had a higher re-identification rate (58% photographed in multiple years, range: 1–7 years) compared to B2s (31%, 1–4 years). We fit mark-recapture models that allowed temporary emigration beyond the study area, to effectively monitor the size of wide-ranging populations and documented contrasting trends for B1s and B2s. A smaller population size (~102) of B1s was estimated to use the area, with a declining trend in abundance (−4.7% per year) and reduced apparent survival in recent years. In contrast, a much larger population size (~740) of B2s was estimated to be generally stable in abundance and apparent survival over the past decade.

中文翻译：

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十年的照片识别揭示了南极半岛沿海水域 B 型虎鲸的丰度和趋势对比

南极半岛 (AP) 正在迅速变暖，需要有关海洋生物丰度趋势的经验数据来了解这些物理变化以及相互作用的人为影响对生态系统的影响。最近的估计推断，在这条食物链的顶端，A 型虎鲸的数量越来越多，在这里，我们使用 2008/2009 年至 2017 年南方夏季收集的摄影标记重新捕获，提供有关 B1 型和 B2 型虎鲸数量的新数据/ 2018 年。两种生态型都经常在美联社海岸线周围拍照，特别是在西侧，而且两者的个体多年来都表现出对场地的保真度。与 B2s（31%，1-4 年）相比，B1s 具有更高的重新识别率（58% 拍摄多年，范围：1-7 年）。我们拟合了允许临时迁移到研究区域之外的标记重新捕获模型，以有效监测广泛人口的规模并记录 B1 和 B2 的对比趋势。据估计，使用该地区的 B1 种群规模较小（~102），丰度呈下降趋势（每年-4.7%），近年来表观存活率下降。相比之下，在过去十年中，估计更大的 B2 种群规模（约 740 个）在丰度和明显存活率方面普遍稳定。