Maternal Lineage and Habitat Use Patterns Explain Variation in the Fecundity of a Critically Endangered Baleen Whale

The critically endangered North Atlantic right whale population ( Eubalaena glacialis ) has experienced multiple periods of decreased reproduction within its observable history, which have played a role in the overall decline species. In addition to this synchronized variation across population, there exists considerable individual fecundity. To determine impacts family history and habitat use behavior on these variations fecundity, photo identification data collected during four decades visual monitoring were used create calving index for sexually mature females that could be evaluate matrilineal influence Reproductive life histories analyzed assess fecundity matrilines over time. Individual also assessed with respect recent climate-driven distribution shift by loyal cohort whales Gulf St. Lawrence summer autumn seasons. Lifetime oldest known living reproductive female, or matriarch, matriline was positively associated her female progeny. Sexually since 2015 significantly more likely give birth time period compared individuals who did not habitat. Individuals both sexes if their mothers as well; however, association declined offspring aged. These results provide insight environmental, behavioral, genetic factors contribute Low rates increased dangers posed shifts past decade major species’ decline, new insights into mechanistic drivers show lineage guides progeny success. As anthropogenic climate change continues disrupt seasonal distributions through changing ocean circulation patterns, understanding demographic consequences novel patterns will essential updating protective policies.