Nature Canada
The Laurentian Channel off the coast of Newfoundland and Nova Scotia. Nature Canada, environmental allies, and concerned citizens achieved a significant victory when the federal government announced that the Laurentian Channel would become a marine protected area in 2019.
These whales had fallen victim to many human threats including extreme overhunting as part of the historic whaling trade.

Vital Signs

  • Common name: Sei Whale
  • Latin name: Balaenoptera borealis
  • Status under SARA: Listed as Endangered for the Pacific Population and Data Deficient for the Atlantic Population in a 2013 assessment.
  • Range: Sei Whales have a largely unknown geographic distribution, as their wintering grounds have not yet been identified. However, Sei Whales can be found in oceans in the sub-polar latitudes in each hemisphere during the summer months, and in sub-tropical waters during the colder months.
  • Life span: The oldest recorded age is 74 years in the wild.
  • Size: Females are slightly larger than males. These whales average 15-19 tonnes, and have an average length of 15m.
  • Population estimate: With the lack of recent data collection, the Canadian population is estimated to be fewer than 250 mature individuals.

The Facts

Balaenoptera borealis are part of the Rorquals, a group of baleen whales which include the largest animals on Earth. Sei Whales are the third largest whale after Blue Whales and Fin Whales. Their common name, sei originates from the Danish word for Pollock fish and hval is whale in Danish. These whales were named after Pollock because they were seen in abundance while Norwegian fishers hunted for Pollock fish.

Sei Whales are baleen whales, which refers to the structure of their teeth. Instead of the common mammal tooth form, baleen whales have plates for filtering foods in and filtering water out. Different baleen plate forms emphasize the type of prey food they eat; thus baleen whales tend to be specialists in their diet. Sei Whales are unique in that unlike most rorquals, they are capable of eating all types of micro-crustacean species, making it easier for this species to adapt to its environment. B. borealis also happens to be the fastest swimmer among the baleen whales. They can gain speeds of 30 knots (30 nautical miles per hour!) in short bursts.

Although much is unknown about Sei Whales, their habitats are primarily pelagic (open water) locations associated with continental shelves. This is most likely due to the optimal locations for finding their typical prey foods, including copepods, amphipods and plankton. Small fish and squid can also pass through Sei Whales’ baleen plates and thus also contribute to their diet. Sei Whales are streamlined, with small dark-grey to bluish patches and paler colours on their belly.

The Sei Whale’s Canadian range encompasses both coasts, and they are sometimes spotted along the coast of British Columbia and in the waters off of  Newfoundland. While this species is found worldwide, it is largely restricted to deep waters in the temperate latitudes between the poles and the tropics, as they are sensitive to overly cold and overly warm waters. Once a female is pregnant, she will begin her migration north to her feeding grounds. After 10.5-12 months of gestation, she will give birth to a single live baby whale called a calf. Her calf is weaned after 6 months but she will continue care for it closely and will not become pregnant for another 2-3 years.

The Story

B.borealis unfortunately has a sad story. These whales had fallen victim to many human threats including extreme overhunting as part of the historic whaling trade. During the 1960’s, a wave of whaling took the Sei Whale’s global population from between 58 000 to 62 000 individuals to between 7 260 and 12 260 individuals by 1974. Studies showed that this heavy exploitation caused the age of maturation of female Sei Whales to decrease from 10-11 years to just 8 years.

One significant impact factor for Sei Whales today is noise pollution, such as seismic testing for undersea oil and gas reserves. Noise pollution underwater has negatively affected numerous aquatic species, but particularly whales, dolphins and other marine animals that use echolocation (like sonar) for social communication and to navigate their environment. The increased amount of shipping traffic worldwide has  also increased the risk of whale strikes at sea.

Sei Whales are also impacted by human sources of pollution that end up in the ocean, such as plastics and contaminated run-off. Overfishing and commercial fisheries also degrade habitat and create food shortages for many animals, including Sei Whales, which then have nowhere to go and nothing to eat.

What’s Being Done

In 2006, a multi-species Recovery Strategy was developed under Canada’s Species at Risk Act that included the Pacific Sei Whale as well as the Pacific Blue and  Fin whale populations in Canada. The goal of this Recovery Strategy is to attain long-term viable populations of the Sei Whale in Pacific Canadian waters. This is done through the identification of critical habitats, determining the species distribution, and mitigating threats in Canada’s marine realm.

Fisheries & Oceans Canada (DFO) runs a Cetacean Research Program in which participants conduct annual surveys at sea to help determine the presence of Sei Whales in Pacific Canadian waters. During these surveys, individual whales sighted are photographed for identification and comparison with catalogs of known whales sighted in U.S. waters. Sightings of all whale species on the west coast have also been collected by the Vancouver Aquarium Marine Science Centre’s BC Cetacean Sightings Network since 1972, which is helping to determine the distribution of many species including Sei Whales. As well, the Cetus Research and Conservation Society is working with a network of volunteers to solicit, collect, verify, and record whale sightings.

Fisheries & Oceans Canada also has a Marine Mammal Incident Response Program to respond to incidents involving marine mammals, including Sei Whales. These incidents can include violations of the Fisheries Act and/or the Species at Risk Act; live strandings; dead, sick or injured animals; or entanglements with fishing gear or other marine infrastructure. All incidents involving Sei Whales in Pacific Canadian waters are compiled by the program and will be used to better identify threats and develop specific mitigation strategies. Fisheries & Oceans Canada is developing predictions of Sei and Fin Whale habitat to focus survey effort and identify ‘potential’ habitat, an important component to the identification of critical habitat.

The Cetus Research and Conservation Society is also working to reduce overall impacts on marine animals through ’Straitwatch’. This program provides education to northern Vancouver Island residents and visitors in the hopes of increasing awareness of conservation issues and local marine species at risk like the Sei Whale. A stewardship vessel patrols areas of concern providing marine mammal guidelines and species at risk information to boaters while monitoring activities that may be potentially harmful to vulnerable species.

What You Can Do

  1. Focus on purchasing sustainably harvested seafood such as something Marine Stewardship Council certified.
  2. Avoid products (like foreign cars) that are shipped overseas by container ships.
  3. A safe practice is to not flush chemicals down your drain. Be sure to dispose of them safely at your local hazardous waste centre or contact your city to find out where the appropriate place to dispose of these chemicals safely.
  4. Be aware of what’s going on by researching yourself on endangered species. Reading these endangered species profiles and then passing on the info is the best way to get more people on board to save our nature’s wildlife.
  5. Become a part of Habitat Stewardship Program for Species at Risk. Read the following link for more information on what you can do in your hometown to help out all species at risk.
  6. Help us protect marine habitats and species at risk by becoming an Ocean Defender.


SARA Recovery Plans
Sei Whale Facts
SARA Species Profile
Report on Recovery Plan

Want to Help?

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