“Is a steelhead a salmon… or a trout?”
This is a common question at the pool in the Western Cascades, where my dogs and I have spent more than 18 seasons guarding the wild summer steelhead holding there. The question is complex and I often fail to answer it very well.
First, some rainbow/steelhead taxonomy: Millions of salmon-generations ago, rainbow and cutthroat trout swam in the ocean and the rivers of the region now known as the Pacific Northwest. At that time, the Chinook, coho, chum, pink, and sockeye, as we now know them, had yet to evolve into separate species. The fish that we have come to call cutthroat trout and rainbow are the oldest species and resemble the common ancestors of the genera we have eventually named Oncorhynchus
— hooknose — the Pacific salmon and Salmo
— leaper — the Atlantic salmon.
All of these salmon-generations ago, there were no human beings in ecologies of the greater Pacific Northwest, in all of North America, or even yet in East Africa. Our hominid ancestors had yet to learn how to systematically fracture stone or make tools of bone or wood. Not existing, we humans had yet to evolve linguistic terms describing or naming these migratory, taxonomically unconstrued wanderers that swam the North Pacific and its streams.
In 1792 CE — approximately 56 salmon-generations ago — a German naturalist, Johann Walbaum, studied a trout from the Western Kamchatka Peninsula and named the species mykiss
, which was the word used by the indigenous Koryak people to name this fish. Believing this trout to belong to the Atlantic salmon genus, Walbaum ended up calling it Salmo mykiss
Forty-four years later, in 1836 CE — approximately 44 salmon-generations ago — a Hudson’s Bay Company naturalist named Richardson gave the scientific species name of gairdneri
to a rainbow trout from the basin of the Columbia River. The species name honored Meredith Gardner, a Hudson’s Bay Company surgeon. He believed the rainbow belonged to the Atlantic salmon genus, Salmo
, and Richardson gave it the name Salmo gairdneri
Nearly a century and a half later, the taxonomy of the rainbow trout was reassessed by Smith and Stearley in 1989 CE — approximately seven salmon-generations ago. Their work unambiguously demonstrated that the rainbow trout was the same species as Walbaum’s western Kamchatka trout. Further, their reclassification showed that the rainbow was anatomically and biochemically more closely related to the Pacific salmon genus — Oncorhynchus
— than to Salmo
, the Atlantic salmon genus.
Because the name mykiss
, it took precedence and the more recent species name was discarded. Additionally, the reassignment of the rainbow from the Atlantic salmon to the Pacific salmon genus meant that, insofar as scientific nomenclature is concerned, the name long in use, Salmo gairdneri
, was supplanted by Oncorhynchus mykiss
. This is the way biological nomenclature works.
Most of the people who ask me whether a steelhead is a salmon or a trout know that steelhead is a kind of rainbow that goes to the ocean as part of their life cycle. They may also know that steelhead and rainbow are the same species without necessarily knowing their scientific name is O. mykiss
Since I first read about the change, it has always seemed to me that one of the nice and sensible things about placing the rainbow and the cutthroat in the Oncorhynchus
genus was that you now had salmon that are exclusive to the Pacific Basin and others that are equally exclusive to the Atlantic Basin, or Salmo
. This matches that — before the horrendous and ruinously thoughtless spread of hatcheries and fish farms — there were no rainbows east of the Rocky Mountains and no Atlantic salmon west of them. Please note that the brown trout are not native to North America.
This renaming of the rainbow as Oncorhynchus mykiss
has had no effect on the fish itself, of course. I mention this because, at the time of this reclassification, I read several articles in sporting magazines lamenting the revision. This aversion to change is probably an essential part of human nature but it may as well be due to the hysterical nature of anglers — myself included. How else can you explain the emotional tone common to these articles written by people who had never called a rainbow or steelhead by its scientific name before in their lives?
So now back to the initial query: Is a steelhead a salmon or a trout?
Before Smith and Stearley, many people in the Pacific Northwest have been inculcated since they were small that trout and salmon were mutually exclusive terms. Maintaining the salmon/trout dichotomy could also have made learning easier. If I am right, this quasi-organic dualism of the words "trout" and "salmon" may make it difficult for some folks to comprehend that some fish are both salmon and trout.
Again and again I have seen the face of a visitor contort as they attempt to absorb this idea. Usually, I lose them immediately when I start to explain that the word "salmon" has a modicum of scientific meaning, as when it is used in the term "Pacific salmon," but that, while trout is unquestionably a useful word, it is a common, or casual, word and does not have scientific meaning other than in the most general way.
It doesn’t help when I say that a steelhead is a rainbow trout that goes to the ocean as part of their life history. Most people already know this. It appears to be even less helpful when I explain that most scientists now consider rainbow to be a salmon. I have heard some people wonder out loud whether a trout can metamorphose into a salmon and back again.
By this time in the interaction I am trying my damnedest not to slip up and use the word that has grown singularly troublesome and — I think — confusing and meretricious: trout
After trying to clarify this situation time and again and once more, now I mostly say that steelhead are both a trout or a salmon and wait…
When it becomes apparent that I have failed, I often fall back on humor:
Me: “So, do you know what you call a spawned-out spring Chinook?”
Visitor: “No. What do you call a spawned-out spring Chinook?
Me: “A sprung Chinook.”
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was born during the autumn of 1950 in Portland, Oregon. At the age of two he moved to Minnesota. Twenty-six years later he acquired a master’s degree from the University of Oregon in anthropology with a specialty in prehistoric archeology. Shortly after taking up his profession, he began to cast flies for steelhead, focusing on the North Umpqua River, one of the truly gorgeous rivers of the world. In 1999, he and Sis, his sweet pup, volunteered to camp at a secluded pool and deter poachers in a protected tributary to the North Umpqua. Nineteen years later, he and his next sweet pup, Maggie, are still there. A Temporary Refuge
is his first book.