We investigate the recent history and stock identity of beluga whales (Delphinapterus leucas) in Kotzebue Sound in the Chukchi Sea, a region long frequented by large numbers of belugas in summer until their near disappearance in the 1980s. Wide variation in numbers since then suggests a complex recent history that hinders recovery efforts. Analysis of teeth sampled during the historical (pre-decline) era using ancient DNA (aDNA) methods found that the original Kotzebue Sound whales were differentiated for mitochondrial DNA (mtDNA) from other summering concentrations across the Pacific Arctic revealing a demographically distinct subpopulation where long-established migratory culture likely facilitated population divergence. Analysis of microsatellite (nDNA) and mtDNA markers in belugas from the contemporary (post-decline) era revealed that whales from other stocks likely visited Kotzebue Sound, including during two low ice years when relatively large numbers of whales were present. Some mtDNA lineages were found only in Kotzebue Sound, with one recorded in both the historical and contemporary eras. Exclusion tests found a number of whales in Kotzebue Sound during the contemporary era that had nDNA genotypes unlikely to arise in other contemporary stocks in the Pacific Arctic. Our findings indicate that the Kotzebue Sound belugas comprised a unique stock of which a few remnants likely still co-occur with belugas from other larger stocks. We recommend that the US government work through the co-management process to greatly reduce or eliminate the taking of belugas, especially adult females, likely to belong to the Kotzebue Sound stock, until they recover.

中文翻译：

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科策布湾白鲸的遗传历史和种群特征

我们调查了楚科奇海 Kotzebue 海峡中白鲸 (Delphinapterus leucas) 的近期历史和种群特征，该地区夏季长期以来一直是大量白鲸经常光顾的地区，直到 1980 年代它们几乎消失。从那时起，数字的巨大差异表明，近期的复杂历史阻碍了恢复工作。使用古代 DNA (aDNA) 方法对历史（衰退前）时期取样的牙齿进行分析发现，原始的 Kotzebue Sound 鲸的线粒体 DNA (mtDNA) 与整个太平洋北极地区的其他夏季浓度区分开来，揭示了一个人口统计学上不同的亚群，其中长- 既定的迁徙文化可能促进了人口分化。对当代（衰退后）白鲸体内微卫星 (nDNA) 和 mtDNA 标记的分析表明，来自其他种群的鲸鱼可能曾到过 Kotzebue Sound，包括在鲸鱼数量相对较多的两个低冰年。一些 mtDNA 谱系仅在 Kotzebue Sound 中发现，其中一个在历史和当代都有记录。排除测试发现，当代科策布海峡的许多鲸鱼具有不太可能在太平洋北极的其他当代种群中出现的 nDNA 基因型。我们的研究结果表明，Kotzebue Sound belugas 是一种独特的种群，其中一些残余物可能仍与其他较大种群的白鲸共存。我们建议美国政府通过共同管理程序来大大减少或消除对白鲸的捕杀，