Biology:Northern resident orcas

Short description: Orca community in the North Pacific

Northern resident orcas, also known as northern resident killer whales (NRKW), are one of four separate, non-interbreeding communities of the exclusively fish-eating ecotype of orca in the northeast portion of the North Pacific Ocean. They live primarily off the coast of British Columbia (BC), Canada, and also travel to southeastern Alaska and northern Washington (state) in the United States. The northern resident population consists of three clans (A, G, R) that consists of several pods with one or more matrilines within each pod. The northern residents are genetically distinct from the southern resident orcas and their calls are also quite distinct.

Population Estimates

Date	A Clan	G Clan	R Clan	Total	Reference
2020	172	96	57	325
2021	175	98	59	332

Social structure

Further information: List of northern resident orca pods

Like the Southern residents, the Northern residents live in groups of matrilines. A typical Northern resident matriline group consists of an elder female, her offspring, and the offspring of her daughters. Both males and female orcas remain within their natal matriline for life. Matrilines have a tendency to split apart over time. Pods consists of related matrilines that tend to travel, forage, socialize, and rest together. Each pod has a unique dialect of acoustic calls. Pods that share one or more certain calls belong to a common clan.

Behaviours

In the summer months the Northern residents can often be observed swimming close to shores of Johnstone Strait and positioning their stomachs to rub themselves on beach pebbles. More than 90% of the Northern resident population observed in Johnstone Strait visit these rubbing beaches. They emit certain and specific calls more frequently while engaging in this activity. Although it is not clear why they engage in this activity, beach rubbing has been identified as an important activity to the culture of the entire Northern resident community. This behaviour was originally thought to be unique to the Northern resident community; however, the Southern Alaska resident killer whales have also been observed beach rubbing.

Location

The Northern residents have been seen as far south as Gray's Harbor, Washington and as far north as Glacier Bay, Alaska. From spring until mid-summer, the Northern residents are commonly found in Chatham Sound near the BC–Alaska ocean border and in Caamaño Sound between Haida Gwaii and the BC mainland. From June until October, they are commonly found in Johnstone Strait. The habitat of the Northern residents overlaps with the Southern residents; however, the two types of orcas have never been observed together.
Members of A clan have been the most commonly sighted whales off northeastern Vancouver Island, whereas G clan is most commonly sighted off the west coast of Vancouver Island, and members of R clan are most commonly sighted in the northern parts of the community's range.

Conservation efforts

In 2008, the Canadian Ministry of Oceans and Fisheries designated the waters of Johnstone Strait and southeastern Queen Charlotte Strait as critical habitat and legally protected under a Critical Habitat Order. In 2018, the western part of the Dixon Entrance along the north coast of Graham Island from Langara Island to Rose Spit was also identified as critical habitat for the Northern residents.

General references

• Colby, Jason M. (2018). Orca: how we came to know and love the ocean's greatest predator. Oxford University Press. ISBN 9780190673116. 

• Ford, John Kenneth Baker (1984). "Call Traditions and Dialects of Killer Whales (Orcinus Orca) in British Columbia.". Retrospective Theses and Dissertations, 1919-2007 (University of British Columbia). doi:10.14288/1.0096602. 

• Ford, John K.B.; Ellis, Graeme M.; Balcomb, Kenneth C. (2000). Killer Whales: the natural history and genealogy of Orcinus orca in British Columbia and Washington (2nd ed.). Vancouver, BC: UBC Press. ISBN 9780774808002. 

• Hoyt, Erich (2013). Orca: the whale called killer (eBook ed.). Richmond Hill, Ontario: Firefly Books Ltd.. ISBN 9781770880672. 

• Hubbard-Morton, Alexandra (2002). Listening To Whales: What the Orcas Have Taught Us. Toronto: Random House. ISBN 9780307487544.