As the temperatures of the Gulf of St. Lawrence rise, recent Canadian research indicates a change in the diets of certain baleen whales due to shifting prey availability. Lead author Charlotte Tessier-Larivière from Université du Québec à Rimouski highlighted a decline in Arctic krill, an essential food source for fin whales in the 1990s. The study reveals that fin and minke whales have adapted by increasing their consumption of forage fish like capelin, mackerel, and herring, which are also primary food sources for humpback whales in the region.
According to Tessier-Larivière, the research demonstrates the whales’ ability to adjust their diet based on the availability of preferred prey. However, the full extent of their adaptive capacity remains unknown. The study raises concerns about potential competition for food resources among whale species if the prey populations decrease.
Hanna Vatcher, a campaigner at Oceana, finds the study results both encouraging and distressing. She emphasizes that the changing ocean conditions, driven by climate change, are affecting various marine species, from large whales to small forage fish, in real-time.
The research involved analyzing tissue samples from different whale species and their prey over 28 years, using carbon and nitrogen isotopes to track dietary changes. In recent years, an increase in forage fish signatures was observed in the tissues of fin, minke, and humpback whales.
While the study indicates that the whales are consuming similar prey, it also shows evidence of resource partitioning, suggesting that they are targeting different fish species to minimize competition. Janie Wray, CEO of BC Whales and North Coast Cetacean Society, highlights the intelligence of whales in adapting to fluctuating prey availability and explains the cooperative feeding strategies observed among humpback and fin whales.
Wray’s recent research on bubble net feeding by humpback whales showcases their sophisticated hunting techniques, including collaboration with other whale species for foraging. She underscores the importance of studying whale behaviors to identify and protect critical marine habitats that support whale populations.
The study underscores the significance of understanding and preserving marine ecosystems to safeguard whale habitats. Vatcher emphasizes the need for dynamic conservation efforts that consider climate-informed adaptive management to protect whales and their food sources in the face of changing environmental conditions.
