BLUE WHALE

Blue whales (Balaenoptera musculus) are the largest known animals to exist on the planet, reaching up to 29.5 meters in length. They exist in all oceans of the world in three distinct subspecies, two of which occur in Canadian waters. Blue whales are low trophic level foragers, consuming between two and four tonnes of prey per day. They typically live between 70 and 80 years, and females give birth every two to three years, with calves weighing two to three tonnes and measuring six to seven metres at birth.

The eastern North Pacific population is estimated at 2,000 animals, who undertake extensive, seasonal north-south migrations each year. They migrate from wintering grounds in the low latitudes as far south as Mexico and Costa Rica to summer feeding grounds in the productive, high-latitude Arctic waters. This population may represent anywhere from 12 to 50 per cent of the world’s total known blue whales. Though recent sightings of blue whales off British Columbia have been rare, bottom-mounted hydrophones have detected a consistent intensity of blue whale calls originating from these waters. Blue whales tend to travel alone or in small groups in the open ocean.

Why Blue Whales Are At Risk

Both historic and current threats have contributed to the decline of blue whales, and resulted in the species being designated as endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and protected under the Species at Risk Act (SARA). Blue whales were the first target of modern commercial whaling, which led to severe depletion of their populations in all oceans of the world, before being put under worldwide protection by the International Whaling Commission (IWC) in 1966. There is clear historical evidence of the depletion of blue whales off British Columbia, with at least 650 whales being killed from 1900 to 1967. Today, blue whales may face many threats, including increasing noise levels from shipping, sonar, military operations and oil and gas exploration. Other threats include ship strikes, intrusive whale watching tours in some parts of their range, and exposure to pollution. As well, any activities that degrade or displace blue whales from critical foraging habitat represent a threat to the species.

What’s Being Done

The endangered North Pacific blue whale population is protected in Canada under the Species at Risk Act (SARA). DFO is developing a multi-species Recovery Strategy for blue, fin, and sei whales together to address the threats to their long-term survival in the wild. A range of research work is underway, including acoustic monitoring and ship-based surveys to gauge population levels and current threats.