earth science

Northern resident orcas

Northern resident orcas is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Northern resident orcas rather than just read about it. In short: 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.

Key takeaways

Northern resident orcas belongs to earth science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Northern resident orcas to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Northern resident orcas from memory before moving on to harder problems.

Reference excerpt

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.

Social structure 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 Grays 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.

List of pods This is a list of northern resident orca pods that live off the coast of British Columbia, Canada, as of March 2013.

Asterisk indicates deceased member.

References

Further reading 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 (Thesis). 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.

Worked examples

Example 1 — a first encounter with Northern resident orcas

Start with the simplest possible case. Write down what Northern resident orcas claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Northern resident orcas before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Northern resident orcas ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Northern resident orcas

In research: Northern resident orcas appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Northern resident orcas in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Northern resident orcas is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cetaceans of the Pacific Ocean, Cetology, Endemic fauna of the Pacific Northwest, so understanding it makes those chapters shorter.
In everyday life: Look for Northern resident orcas outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Northern resident orcas in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Northern resident orcas means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Northern resident orcas out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Northern resident orcas in simple terms?

Why does Northern resident orcas matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Northern resident orcas?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Northern resident orcas.