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Resident & Bigg’s (Transient) Killer Whales: Scientists Revealed There Are 2 Species of Orcas in the North Pacific

a body of water with a mountain in the background

The ocean is full of wonders, and whales are among the most majestic and mysterious creatures in the big blue. Orcas, commonly called killer whales after they prefer hunting other marine mammals, roam every ocean in the world. Up until recently, scientists have grouped all orcas into one species. That seems to be changing this year, as researchers are revealing two species of orca in the North Pacific, resident killer whales, and Bigg’s killer whales, also known as transient orcas.

Killer Whales (Orcas) Overview

Killer whales are fascinating animals. Indigenous people in places as far apart as Alaska and Australia have observed and interacted with these large marine mammals for thousands of years, but Europeans only described them scientifically in the mid-16th century.

Officially, scientists place orcas in the same family as dolphins and label them with the same scientific name: Orcinus orca. Growing between 20 and 30 feet long, killer whales are skilled hunters and eat fish, sea lions, sharks, and more. Some groups of orcas communicate and have distinct social rituals, while others are quiet and enjoy more isolation.

Are There Different Species of Killer Whales (Orcas)?

For more than 150 years, scientists have grouped all killer whales into one species. This is true, even though orcas are incredibly diverse. They don’t look the same, eat the same diet, or roam the same seas.

Scientists have observed these differences since at least the 1970s. Still, early sketches made by European whalers in the 19th century also confirm that at least two distinct types of orcas existed in the North Pacific. However, experts specializing in taxonomy and the scientific naming of animals require thorough evidence before agreeing to separate a group of animals into distinct species, and researchers have not been able to satisfy the requirements until very recently.

animal on the water

Resident Killer Whales Vs. Bigg’s (Transient) Killer Whales

The waters of Puget Sound in the Pacific Northwest are home to two groups of killer whales with different habits. Resident killer whales eat salmon and other fish, while Bigg’s killer whales eat primarily marine mammals such as sea lions and other whales.

Resident killer whales also have different family structures compared to Bigg’s killer whales. One group travels in pods and communicates often, while the other, Bigg’s killer whales, move in very small groups and stay almost completely silent while hunting to avoid alerting other animals of their presence.

Surprisingly, these two groups of orcas do not interbreed. They avoid each other. These behaviors and recent breakthroughs in DNA analysis have convinced scientists to distinguish each group as a separate species. Resident killer whales will now be known as Orcinus Ater and Bigg’s killer whales will be known as Orcinus rectipinnus.

Scientific Discovery of the Two Species

In the 1970s, a Canadian researcher named Michael Bigg documented the differences between the two types of killer whales in the North Pacific and used the common names “resident” and “transient” to distinguish between them. In 1992, a marine biologist, Robin Baird, argued in a paper that these two orcas constituted distinct species. However, it took 20 years for genetic research methods to improve enough to show that resident and Bigg’s killer whales have diverging DNA patterns and are factually different species.

Conservation Efforts & Implications

The implications of this scientific discovery are far-reaching. First, conservation efforts are pinned to species, so designating more than one orca species will improve these animals’ protective measures. Second, this decision paves the way for experts to identify even more species of orca, which will help scientists understand these animals’ relationships and ecosystems on a deeper level.

Consider booking a whale-watching trip for you and your family to see a killer whale in person. Take advantage of the opportunity of a lifetime to encounter these creatures in the wild.