British Columbia

Salmon or trout: What the heck is a steelhead, anyway?

Until just a few days ago, anyone interested in learning about B.C.’s struggling steelhead might stumble upon a DFO website describing them as a type of Pacific salmon.

Meet the anadromous subspecies of Oncorhynchus mykiss, a trout that behaves like a salmon

Steelhead are a subspecies of Oncorhynchus mykiss. (Matt Joyce)

Until just a few days ago, anyone interested in learning about B.C.'s struggling steelhead might stumble upon a website from Fisheries and Oceans Canada describing them as a type of Pacific salmon.

The fish, according to this now-defunct page, "were at one time considered a trout species but have been discovered by biologists to be more closely related to Pacific salmon than other trout."

There's just one problem with that: The current consensus is that steelhead aren't salmon, they're trout.

The page was changed on Dec. 18, and now contains a fact sheet about all the different varieties of Pacific salmon, without a single mention of steelhead. The previous version was outdated, and the fact that it was still online was "just an oversight," a DFO spokesperson wrote in an email.

A Fisheries and Oceans Canada webpage about steelhead, as it appeared on Dec. 18, 2017. (Fisheries and Oceans Canada)

All this confusion leaves Steelhead Society of B.C. president Brian Braidwood a bit exasperated.

"I don't care what they are, these governments that are responsible for their well-being need to get serious about protecting them," Braidwood told CBC News.

Only about 200 steelhead returned to the Thompson River this year and fewer than 50 came back to the Chilcotin River, according to Braidwood's group. The Committee on the Status of Endangered Wildlife in Canada is undertaking an emergency assessment of the species.

A trout that behaves like a salmon

The fact remains that the steelhead really is a perplexing beast.

It belongs to the same species as rainbow trout — Oncorhynchus mykiss — but it acts a whole lot like a salmon.

"All those trout hatch in gravel-bottom, fast-flowing, well-oxygenated rivers and streams," explained Paul Grant, a Species at Risk Act science coordinator for DFO.

"Some stay in the freshwater all their lives and those are the rainbow trout. The steelhead are the anadromous form that migrate into the ocean and they change colour and get much, much larger than the resident rainbow trout."

Rainbow trout don't grow as large as steelhead. (Steve Peng)

Just like Pacific salmon, steelhead return to the rivers where they were born to spawn.

Unlike salmon, however, they don't necessarily die after that happens — some will actually return to the ocean. And they don't necessarily need to go out to sea to complete their life cycle.

Reshuffling the family tree

It seems the mighty steelhead has been bouncing between the salmon and trout categories for years. Even as trout, the current thinking says they're more closely related to Pacific salmon than to trout species in other parts of the world.

"There's all these family trees and they do get reshuffled, especially nowadays, based on the genetic evidence," Grant said. "They're finding a lot of relationships based on genetics that weren't previously known."

Take, for example, a 1994 booklet from the DFO, alluringly titled "The Incredible Salmonids." It definitively calls steelhead a trout, but adds another wrinkle, referring to the fish by an outdated scientific name: Salmo gairdneri.

That name, which dates back to the 1800s, placed steelhead next to Atlantic salmon on the tree of life. Scientists recommended a change in the steelhead's taxonomy in 1989, saying the old name was an error.

A 'hotly debated' question

Today, the Pacific Salmon Foundation still lists steelhead alongside the salmon species it works to conserve, calling the steelhead's classification a "hotly debated" topic.

Even the province, which is responsible for managing sport fishing regulations for steelhead, straddles the line somewhat.

"As steelhead undertake large ocean migrations, they are more salmon than they are trout," a spokesperson for the forests ministry wrote in an email. That same email, however, goes on to acknowledge that steelhead are indeed the ocean-going version of rainbow trout.

Just 200 steelhead returned to the Thompson River this year. (Sean Mahar)

But Brian Braidwood worries that all of this academic discussion about nomenclature might soon become moot if the threats to steelhead aren't addressed — things like commercial salmon fisheries and changing ocean conditions.

"Can we try and do something about this before they go extinct?" he asked. "It's the same thing since the '70s, it's just we've gone from 6,000 fish to 5,000, 3,000, 2,000, 1,000, and now here we are at this year, 200 in the Thompson. It's time for these governments to get serious about their jobs."


Bethany Lindsay


Bethany Lindsay is a Vancouver-based journalist for CBC News. Questions or news tips? Get in touch at or on Twitter through @bethanylindsay.