Keywords: Mammals, Killer whales, Salish Sea Currents magazine, Species of concern

Scientists are making the case that the world's orcas should be divided into two new species. Voting for the proposed change was scheduled to take place last week at the Society for Marine Mammalogy. [Update: Read about the decision here.]

Killer whales worldwide are currently identified as a single species, Orcinus orca. But two new species of orca, representing thousands of whales in the North Pacific, could be added to the scientific nomenclature within the next month [Editor's note: information about the the decision is now available].

Evidence supporting the new species has been submitted for consideration to the Society for Marine Mammalogy, widely recognized as the leading authority for naming new species of marine mammals. If approved, the change could inspire further studies of unique orca populations in every ocean of the world and perhaps lead to the designation of even more orca species or subspecies.

Killer whale observers in the Pacific Northwest have long recognized two distinct types of orcas, the fish-eating residents and the marine-mammal-eating transients or Bigg’s killer whales. These two “ecotypes” generally share the same waters, but they do not interbreed. In a scientific article published in Royal Society Open Science, geneticist Phillip Morin of NOAA’s Southwest Fisheries Science Center and other researchers showed distinct differences in physical attributes, behavior, vocalizations and genetics between these two ecotypes, which stand apart from other orca populations.


A map of the northern Pacific Ocean showing the range of resident killer whales in blue overlain on a the larger range of Bigg’s killer whales in pink. Illustrations of both types of whales (male and female) are placed below the map.

An estimate of the locations where the two proposed species of orca might be found. The range for the Bigg’s killer whales, shown in pink, is larger than that of the residents, shown in blue and lying over the Bigg’s range in this map. Map: NOAA; whale illustrations: Uko Gorter

Following years of study, the researchers say they have amassed enough evidence to designate both residents and Bigg’s as their own unique species. Under the proposal, residents would become Orcinus ater, while Bigg’s would become Orcinus rectipinnus. These species names were first referenced in a scientific journal article in 1869, although these “species” were later abandoned for lack of distinctive evidence.

While new marine mammal species and their scientific names are subject to review by the Society for Marine Mammalogy, such is not the case with common names, such as “resident” and “transient.” Phil Morin and his collaborators proposed abandoning the terms “transient” and “resident,” because they implied behaviors that are no longer accurate. The name “Bigg’s” for “transient” would honor the late Mike Bigg, a killer whale researcher who first described the separate ecotypes. A replacement for the term “resident” has yet to be widely discussed, and it could provoke disagreement. But it is important to recognize that a common name is no more or less than what people choose to call something.

The new species proposal is focused on just the two groups of orcas — residents and Bigg’s — leaving many other known or suspected populations to be defined later when more data becomes available. For example, in the deep ocean waters along our West Coast, at least two other groups of whales have been observed. One group, called “offshores,” are more closely related to residents than to transients, but their diet primarily consists of sharks rather than salmon. Although some genetic information is available, researchers have yet to determine whether offshores might be a separate species, subspecies or other classification.

Another group of deep-ocean killer whales has yet to be widely recognized. These whales seem to stay far out at sea, beyond the continental shelf in the deepest parts of the ocean, according to reports. In a paper published in March in the journal Aquatic Mammals, Canadian researcher Josh McInnis described these animals, which he calls “oceanic” killer whales. I will elaborate below, but first let’s look at the process for naming new species.

Taxonomy Committee deliberations

Within the Society for Marine Mammalogy, the 14-member Taxonomy Committee has been charged with determining whether available scientific information is adequate to support the designation of new species. The members have now received the peer-reviewed paper written by Morin and colleagues, and they have been given until June 3 (Monday) to offer their opinion — yes or no — on whether to authorize the two new species, according to Patricia Rosel, a committee member and former chairwoman.

The change in species designation requires a two-thirds majority of committee members voting on the proposal, according to committee rules. Members tend to come to their conclusions independently, but nothing precludes them from seeking further information. Members are allowed, but not required, to submit written statements supporting their decision, Patricia said.

In the Morin paper, the criteria for naming new species and subspecies are covered one-by-one with supporting documentation. Committee members are expected to review the rationale for new species posed in the paper.

Graph showing relationships between nine populations of killer whales

This phylogenic tree shows the closeness in relationships among various populations of killer whales based on one type of genetic makeup. NE Atlantic T is a tuna-eating population, and NE Atlantic H is a herring-eating population. Three Arctic populations are shown along with the physically distinctive Type D orcas from the Antarctic. Graphic: Morin et al., NOAA Fisheries

As part of its duties, the committee takes up species changes annually. Other species also are up for review at this time, but no decision may be as consequential as that for killer whales, which would break a long-held convention of considering all the orcas in the world as a single species.

Many experts have told me that a change in the taxonomy of killer whales is long overdue, that the evidence for naming these two new species is overwhelming, and that the scientific community needs to start somewhere in recognizing considerable differences among orca populations. But because this change would be so significant, some committee members could argue for a delay until more genetic information is acquired for killer whales beyond the two species up for review. The need to better understand how all orca populations fit into a worldwide taxonomic structure could be an argument in favor of delay.

What is important to understand is that the papers proposing new species are nothing more than “hypotheses” designed to convey the relationships among marine mammals, Patricia said. As such, current taxonomy is subject to change as new information becomes available.

If the new species and the names Orcinus ater and Orcinus rectipinnus are accepted, they would be added to the list of marine mammals maintained by the Society for Marine Mammalogy. The new species would join Orcinus orca under the genus Orcinus in the family Delphinidae.

Such an inclusion into the list carries great weight, but if some scientists disagree, they are free to continue regarding killer whales as a single species — although they should at least acknowledge in published reports that their opinion diverges from the society’s, Patricia said.

Besides adding new species to the all-encompassing list of marine mammals, decisions of the Taxonomy Committee are typically explained in a newsletter that goes out to all members of the society. It isn’t clear when the votes will be tallied or if submitted comments may lead to more discussion. I will update as more becomes known.

Common names in flux

While the common name Bigg’s killer whales is gradually being adopted in scientific papers when referring to the marine-mammal-eating orcas in the North Pacific, some researchers still prefer the long-held name “transients” for these animals. Researcher Mike Bigg came up with the term “transient” because such whales were rarely seen in the inland waters of British Columbia and Washington during the early 1970s, in contrast with the frequently spotted fish-eating residents. But today, the situation has largely reversed, probably because of the increased abundance of seals and sea lions due to government protections, while Chinook salmon are in decline, according to Canadian marine mammal biologist John Ford, who has been promoting the name “Bigg’s” in place of “transients.”

A killer whale swimmng at the surface of open water with its tail in the air.

Should southern resident killer whales (seen here) still be called 'residents,' or should they get a new common name? Photo: Candice Emmons/NOAA Fisheries

While common names — such as “resident,” “transient” and “Bigg’s” — are not subject to review by the Society for Marine Mammalogy, common names are nevertheless important, because we tend to use the most-accepted names rather than the scientific names. Those who discover new species often have the inside track in determining what they are called.

In proposing the two new killer whale species and their scientific names, the Morin paper suggests the “continued use” of the name “Bigg’s killer whale” for Orcinus rectipinnus. It seems that nobody wants to say “rectipinnus” every time the subject comes up.

The paper also talks about consulting with North American Indigenous tribal groups in an effort to reach consensus on a new common name for Orcinus ater. “But in the meantime,” the document states, “we suggest the continued use of ‘resident killer whale’ to maintain consistency.”

Six of the nine authors of the paper are employed by NOAA Fisheries, and officials with that federal agency are considering whether to pursue a consensus for a common name, according to NOAA spokesman Michael Milstein.

“Doing it right would likely require an extensive effort, with lots of coordination with everyone who would be interested,” Michael told me in an email. “We have yet to determine if we have the capacity for that.”

As far as I can tell linguistically, native people did not distinguish fish-eating orcas from those that eat marine mammals. But killer whales were an important part of the culture for many coastal tribes, and words for killer whale exist in numerous native languages from Alaska to California.

Erik Painter, an art teacher at Bremerton High School, took a keen interest in native languages years ago while living among the Navajo, and his interest has intensified through the years. By searching online sources, Erik put together a list of different words for orca from nearly two dozen native languages — but that, he says, is just a sample.

In the Central Puget Sound region, where the Lushootseed language was prominent, orca were called qal̕qaləx̌ič. The pronunciation of the word can be found on a website that celebrates this language.

In Klallam on the northern Olympic and Kitsap peninsulas, the word is q̕ɬúməčən. The pronunciation can be found in a video titled “Blackfish Power” at 2:03, (“Blackfish” is another name for killer whale or orca.)

Other words for killer whale are kawad in Makah; kaalin, Quinault; kaałin, Quileute; kakaw'in, Nuu-chah-nulth (formerly Nootka on the West Coast of Vancouver Island); sgáan, Haida (at Haida Gwaii or Queen Charlotte Islands);and many more.

One option mentioned by Erik would be to rely on Chinook Jargon, also known as Chinuk Wawa. This language, used all over the Pacific Northwest, grew into common usage during the 1800s to bridge the language barrier among native people, traders, immigrants, missionaries and other people living in the region, as described in an article by writer Diane Selkirk. Most of this language derives from words and phrases that came from Chinook (Columbian River region) and Nuu-chah-nulth (Vancouver Island), with the rest borrowing mostly from French and English, she said.

David Robertson, an independent linguist based in Spokane, told me that the only genuine word he has found for killer whale in Chinook Jargon is “mimlos-whale,” a mixed term that originates from the Olympic Peninsula region. The word literally means “death-whale” or “kill-whale,” he said. Perhaps we could use “mimlos killer whale” as a common name for residents. David writes a blog called “Chinook Jargon,” which discusses all sorts of related linguistic issues.

I can’t leave this subject without noting that the proposal for new killer species not only addresses orcas along the West Coast of North America but also includes closely related orcas along the Asian Coast, including waters off Russia and Japan. In Russian, killer whale is “kocatka.” In Japanese, the word is “Shachi.”

Different populations of killer whales are often recognized with different common names based on where they live, such as Alaska resident killer whales. How much the names might change when killer whales are recognized as multiple species could depend on who is talking, studying and writing about these animals. 

Other West Coast ecotypes

Offshore killer whales, which are known to eat sharks, are more closely related genetically to fish-eating residents than to Bigg’s killer whales, which eat marine mammals. But limited genetic evidence gathered so far shows that they are a distinct group, so it is possible that they will be proposed as their own species when DNA samples are obtained from enough animals to support such a designation.

Physical differences between resident and Bigg’s killer whales — Including distinct jaw structures that have evolved for consuming different prey — are an important characteristic that supports the proposal for making them separate species, according to the Morin paper. For offshore killer whales, more physical and behavioral data are needed for classification, but they do appear to have features that could separate them from the other two types.

Whale fin above water with bite marks at the base of it.

This oceanic killer whale, designated OCX001, is among a growing list of orcas found to  live beyond the continental shelf of the U.S. West Coast. This photograph was taken in 1997 off Morro Bay, Calif., during a dramatic attack upon a group of sperm whales. Note the prominent bite marks from cookie cutter sharks, now recognized as a distinguishing characteristic of oceanic orcas. Photo: Robert L. Pitman/NOAA Southwest Fisheries Science Center

Another group of deep-water killer whales is just coming into the spotlight, based on photographs gathered over 24 years showing individuals that do not match up with other known orcas. Various members of this mysterious group have been seen far offshore from California and Oregon, beyond the continental shelf, and these whales have been known to attack marine mammals as large as sperm whales, according to Josh McInnis, lead author on a report published in the journal Aquatic Mammals. Another rare characteristic among these orcas is that nearly all seem to bear scars from the bites of cookie cutter sharks, which are small parasitic sharks that inhabit deep waters far offshore.

For the report, McInnis and colleagues studied photos and observations showing 49 “oceanic” orcas gathered during nine encounters from 1997 to 2021. After his paper was published in March, Josh received additional information, bringing the total count of the oceanic group to 78, he told me. “We got a lot of information from tuna fishermen,” he noted.

One of the big questions is whether these newly identified orcas are genetically isolated from other killer whales, something that comes about by maintaining geographic separation or behavioral avoidance. If they are a distinct group, they might qualify as a subspecies of Bigg’s killer whales or perhaps even their own species. But information is missing for many of the qualifying factors, including genetics, morphology (physical appearance) and vocalizations, while data on diet and behavior are pretty limited.

“This could be an oceanic population of transients,” Josh said. “There is the fact that they do look a bit different. I don’t think they are related to offshores.”

The “saddle patch,” an identifying whitish-gray pigmentation near the dorsal fin, varies among the oceanics, but for many the saddle patch is narrow like that of orcas in tropical waters, Josh noted. The shape of the dorsal fin — another identifying feature — varies in oceanics from pointy, like Bigg’s, to rounded, like offshores.

Although this is still speculative, it suggests that we have two groups of orcas that eat marine mammals, one far offshore and one in more coastal waters. This might be similar to the relationship between residents and offshores, both eating fish but in different places in the ocean. None of these different types have ever been seen together.

It’s worth noting that the West Coast Bigg’s population consists of two groupings, an inner-coast variety, which seems to prefer harbor seals and sea lions, and an outer coast variety, which generally depends on larger marine mammals available in deeper water. Even these outer-coast whales rarely venture beyond the continental shelf, where the bottom of the ocean drops down to deeper water. Beyond the shelf is where the oceanic orcas are more likely to be found.

Groups of oceanic orcas, as seen by most observers, is between 5 and 12 animals, Josh said. The largest group was 35, which was likely several different families coming together, he added.

This group of 35 orcas was involved in an extraordinary attack on nine sperm whales that were clustered together in a defensive posture some 83 miles off the coast of Central California in October 1997. Biologists aboard the NOAA research vessel David Starr Jordan observed a series of intense attacks over four hours, resulting in one sperm whale being killed and most of the others sustaining severe  injuries, some probably resulting in death over the following days, as reported in the journal Marine Mammal Science.

In other observations, oceanic killer whales were found to be preying on a Risso's dolphins, a pygmy sperm whale, northern elephant seals and even a leatherback turtle.

As for their calls, hydrophones have picked up vocalizations that Josh called “transient-like but very different.” The problem, he said, is that hydrophones alone cannot identify the whales making the sounds. Needless to say, more work is needed to study them up close in the deep waters of the Pacific Ocean, and Josh is making plans to do just that. We'll be waiting for more information about these so-called oceanic orcas.


Two pairs of killer whales swimming in open water with spray coming from their blow holes. Land with green trees and vegetation is in the near background.

A scientific paper, published on March 27th, spells out the unique physical and genetic characteristics that should make each group a separate species, with the proposed scientific names Orcinus ater for residents and Orcinus rectipinnus for Bigg’s.

About the author: Christopher Dunagan is a senior writer at the Puget Sound Institute.

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