16 September 2026: A new study on hybrid blue and fin whales
A study by Pampoulie and colleagues, titled “What Do We Know About Hybrid Blue (Balaenoptera musculus) and Fin (B. physalus) Whales? A Comprehensive Review Across Ocean Basins”, was published in the journal Ecology and Evolution in May 2026.
Hybrids of blue and fin whales have been reported since the late 1800s, with whalers at that time describing caught animals that shared physical traits of both species. Over the last three decades, hybrids continued to be identified, now thanks to dedicated sightings surveys and genetic analysis from tissues of caught whales.
This study performed a review of the available information on hybrid blue–fin whale individuals, collected across the world and throughout historical records, from the oldest accounts to the latest documented individuals. A total of 46 possible hybrid whales were identified, with 17 being genetically confirmed. Notably, some of these whales were either confirmed or suspected to be second generation hybrids (hybrid whales who have at least one hybrid parent), demonstrating that hybrid blue–fin whales are not sterile, as was once thought to be the case.
Blue whale populations were decimated by industrial whaling in the past, and their numbers remain small. In the North Atlantic, there are estimates of 25 times fewer blue whales than fin whales. The large difference in abundance may be pushing blue whales to accept mating with fin whales. This may lead to a reproductive output loss for blue whales, that is, a reduction of the amount of blue whale calves being produced, in favour of hybrid calves. Such an outcome would be concerning, especially since most blue whale populations are still depleted and threatened with extinction.
Nevertheless, the authors state that the underlying causes for hybridisation remain unclear, and the occurrence of hybrids between these two distinct species is puzzling. They recommend further research, by recording and monitoring suspected hybrid individuals and collecting skin samples for genetic analysis.
Read the full paper by Pampoulie et al here: https://doi.org/10.1002/ece3.73630
Photo credit: Lisa Conge