Blue and fin whales are interbreeding
A new genetic study finds that blue whales are mating with fin whales and producing fertile young
An examination of blue whale genetics has revealed that the world’s largest animals have been breeding with fin whales. During a study published in Conservation Genetics, researchers analysed the genomes of the North Atlantic blue whale subspecies – a group still in recovery following extensive whaling in the past – and discovered relatively high levels of fin whale DNA.
Though it has been known that the two species could create hybrids, often called ‘flue’ whales, it was only recently found that these hybrids were fertile. By mating with blue whales, fin whale DNA is introduced into the blue whale population, a process known as introgression.
Strangely, this introgression only seems to be going one way, from fin whales to blue whales, as the hybrids don’t appear to be mating with fin whales. “We don’t know why introgression appears unidirectional,” says Mark Engstrom, co-author of the study, “but it may be related to reproductive behaviour and mating activities of the two species, and also possibly to the much larger numbers of fin whale individuals (and in this case specifically males) compared to the smaller population size of blues.” Engstrom adds that this hybridisation and introgression is not currently a cause for alarm but should be monitored going forward.
“As well as concerns that an endangered species could become extinct, there is also the associated issue of one species being highly protected and the other not,” says Danny Groves, head of communications at Whale and Dolphin Conservation in the UK. “The whale hunts in Iceland have led to hybrid blue and fin whales being killed.” Megan Shersby