Taxonomy
- Kingdom
- Animalia
- Phylum
- Chordata
- Class
- Mammal
- Order
- Artiodactyla
- Family
- Balaenopteridae
- Genus
- Balaenoptera
- Species
- Balaenoptera borealis
Habitat
Northern sei whales inhabit temperate to subpolar waters of the North Atlantic and North Pacific Oceans, preferring deep, offshore pelagic zones. They migrate seasonally from high-latitude feeding grounds in summer to lower-latitude breeding areas in winter. These whales avoid shallow coastal waters and are most commonly found in areas with high plankton productivity.
Diet
Northern sei whales primarily feed on small schooling fish such as herring and mackerel, as well as krill and other planktonic organisms. They use baleen plates to filter food from the water while swimming with their mouths open, typically feeding in surface waters during the summer months in polar regions. Feeding behavior is most active at dawn and dusk when prey is abundant.
Behavior
Northern sei whales are generally solitary or found in small, loose groups of 2-5 individuals, though larger aggregations can occur in feeding areas. They are highly migratory, traveling long distances between summer feeding grounds in cold waters and winter breeding grounds in warmer regions, and are known for their fast swimming speeds up to 50 km/h. These whales exhibit breaching and other surface behaviors, but they are less acrobatic than some other baleen whales and tend to be elusive.
Conservation Status
The IUCN status of the Northern sei whale is Endangered, with population trends showing slow increases in some regions due to whaling bans, but major threats include ship strikes, entanglement in fishing gear, and climate change impacts on prey availability.