In a noteworthy development, scientists have increasingly observed hybrid whales resulting from interbreeding between fin whales and blue whales. This phenomenon, highlighted by recent sightings in the St. Lawrence Estuary in April 2025, underscores the complexities of marine biodiversity and raises important conservation questions.
These hybrids, sometimes called "flue whales," exhibit physical traits of both parent species, making visual identification challenging. Genetic analysis has confirmed that these hybrids are not always infertile, as was previously believed. The interbreeding, known as introgression, appears to be more common from fin whales to blue whales, leading to concerns about the genetic integrity of the endangered blue whale population.
Experts suggest that environmental stressors, such as climate change and declining populations, may contribute to the increased hybridization. Conservation efforts are now focusing on monitoring this trend and protecting the habitats of both species to ensure the long-term health and resilience of these ocean giants. The ability of these hybrids to reproduce also raises concerns about the long-term genetic distinctiveness of blue whales, especially as they face habitat changes and other environmental pressures.