Data from: Groups of related belugas (Delphinapterus leucas) travel together during their seasonal migrations in and around Hudson Bay

Social structure involving long-term associations with relatives should facilitate the learning of complex behaviours such as long-distance migration. In and around Hudson Bay (Canada), three stocks of beluga whales form a panmictic unit, but have different migratory behaviours associated with different summering areas. We analysed genetic variation at 13 microsatellite loci among 1524 belugas, to test hypotheses about social structure in belugas. We found significant proportions of mother–offspring pairs throughout the migratory cycle, but average relatedness extended beyond close kinship only during migration. Average relatedness was significantly above random expectations for pairs caught at the same site but on different days or months of a year, suggesting that belugas maintain associations with a network of relatives during migration. Pairs involving a female (female–female or male–female) were on average more related than pairs of males, and males seemed to disperse from their matrilineal group to associate with other mature males. Altogether, our results indicate that relatives other than strictly parents, and especially females, play a role in maintaining a social structure that could facilitate the learning of migration routes. Cultural conservatism may limit contributions from nearby summer stocks to endangered stocks such as the Eastern Hudson Bay beluga.与亲属间建立长期联结的社会结构，可助力复杂行为（如长距离洄游）的习得。在加拿大哈德逊湾及其周边海域，三个白鲸（beluga whales）种群构成了一个随机交配群（panmictic unit），但它们因各自不同的夏季栖息海域而呈现出差异化的洄游行为。本研究对1524头白鲸的13个微卫星位点（microsatellite loci）的遗传变异展开分析，以验证关于白鲸社会结构的相关假说。 我们在整个洄游周期中均检测到占比显著的母子/母女对（mother–offspring pairs），但仅在洄游阶段，个体间的平均亲缘关系才超出近缘亲属的范畴。对于在同一位点捕获但采样日期或月份不同的个体对而言，其平均亲缘关系显著高于随机预期水平，这表明白鲸在洄游过程中会与亲属网络维持联结。包含雌性个体的个体对（雌-雌或雄-雌对）的平均亲缘关系显著高于雄性个体对，且雄性个体似乎会从其母系群体（matrilineal group）中扩散出去，与其他成熟雄性形成联结。 综合来看，本研究结果表明，除严格意义上的亲本之外的亲属（尤其是雌性个体），在维持可助力洄游路线习得的社会结构中发挥了重要作用。文化保守性或会限制邻近夏季种群对东哈德逊湾白鲸这类濒危种群（endangered stocks）的种群贡献。