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.