Are Brook Trout and Brown Trout Related? A Weird Family Reunion

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Man's hand holding a trout fish above the water.

Yes, brook trout and brown are distant relatives. They are both members of the Salmonidae family. But they are not naturally found in the same habitat. Browns are originally from Europe and western Asia. Brook trout are native to eastern North America.

I can still remember the first brook trout I caught as a kid. Camped with my grandparents, high in the central Colorado mountains, I plucked a stunning brookie from the cold waters of dark-bottomed beaver pond. 

Since that day, I’ve loved brook trout. And they’re easy to love, honestly. 

In austere mountain habitats, they aren’t very picky. Anything that looks like food will get a look. And they might be the most beautiful coldwater fish in the world. I sure think so. 

Brown trout are a different story. Browns are “old world” fish. They, too, are beautiful coldwater trout. But, most anglers, including me, would tell you that browns are more discerning than brookies. They’re just harder to catch

And, even though they’re found in the same rivers and streams across much of western North America, neither fish really belongs there. 

Non-native Game Fish

Brook trout, like this one caught in Idaho.
Brook trout, like this one caught in Idaho, don’t belong in many of the waters where they swim today. They tend to outcompete native fish and eventually, they’ll take over entire watersheds in the western U.S.

Brook trout are native to the Eastern Seaboard of North America, from north Georgia all the way north to Labrador. And brook trout are not trout at all. They are subspecies of char, like Arctic char, lake trout and Dolly Varden.

Brown trout, as noted above, aren’t native to North America at all. If you go fishing in the western U.S. and catch brook trout and brown trout in the same river or stream, you’re catching fish that are not native. Some anglers consider the introduced fish to be “invasive.”

Naturalized for Over a Century

Brown trout, like this one caught in Patagonia, are native to Europe and western Asia.
Brown trout, like this one caught in Patagonia, are native to Europe and western Asia. They can be identified by their light bodies and dark spots, as well as the red spots closer to their bellies. In fresh water, they are often butter-tinged and very beautiful.

While neither fish belong in western North America, both have been there for more than 100 years. Browns were first introduced in the United States in the Baldwin River in Michigan in 1884. They arrived in western waters sometime in the 1890s.

Brook trout were first introduced in western waters in the 1890s, too. And, often, they joined their non-native brown trout cousins in the same rivers and lakes. 

For well over a century, the two shoestring relatives have become naturalized to western American waters, often side by side. They can also be found sharing rivers together in places like Patagonia in far southern South America. 

The logic? Before biologists and anglers understood the impacts of stocking exotic trout and char on top of native fish, there was a desire to increase angling opportunity in waters that didn’t host brookies or browns

Unfortunate Side Effects

Brown trout in man's hand, above the water.
Brown trout are predators. They eat other fish. In the U.S., where they’ve been introduced, they have take over many rivers and streams from native trout.

While the addition of brook trout and brown trout to non-native waters around the globe has, indeed, given you more angling choices, the outcome hasn’t been great

In the West, the native trout is the cutthroat trout. Native char in the region include bull trout in inland waters, and Dolly Varden, a coastal char. 

Both brook trout and brown have negatively impacted our native fish. Brookies are voracious eaters, and they tend to outcompete native cutthroats. Browns tend to be more piscivorous — they eat other fish, including native cutthroats.

Since brook trout and bull trout are both from the char family, they can actually mingle during the spawning season. They produce a fertile hybrid offspring, and, in some cases, brookies have diluted bull trout genetics in otherwise healthy waters. 

Brown trout are expedient predators. They often use native trout for food. They also outcompete native trout for other sources of food, resulting in the decline of the indigenous trout.

A Solution to the Problem?

Brook trout caught in a hook.
Brook trout are among the most beautiful coldwater fish.

While brown trout are generally appreciated by anglers, brookies are not so lucky. Because they are prodigious eaters, they will often over-utilize their habitat. When this happens, they “stunt” and do not get very big. You’ve probably noticed this. In the West, a 10-inch brookie is considered to be a big fish

Many fisheries managers in the West encourage the harvest of brook trout. If you love to harvest and eat wild fish, a good target in the West is brook trout. 

First, they’re among the tastiest of wild trout in the West. Second, harvesting fish removes the brookies that are more likely to eat without caution. The result, if we can remove enough brookies from any given stream, will be bigger fish down the line. 

Because browns get much bigger than brookies, they are rarely targeted for removal. They also occupy bigger water and can tolerate warmer temperatures, which makes them valuable to the angling community. 

Final Thoughts 

Yes, brook trout and brown trout are relatives, even if the connection is tenuous. But, when you find both in the same river, lake or stream, know that neither fish actually belongs there. 

But, because both fish have become naturalized to rivers and streams outside their native ranges, they’ll likely always be present in waters where they don’t belong.

Additionally, brown trout are true trout. Brook trout are members of the Salvelinus genus. They’re char, not trout.  


How Are Brook Trout Different From Brown Trout?

Brookies are a subspecies of char, while browns are true trout. Additionally, neither fish, unless they’ve been artificially transplanted, shares the same habitat. Brookies are from the Eastern Seaboard of North America. Brown trout are native to Europe and western Asia. 

Why Are Brown Trout Harder to Catch?

Browns are more difficult angling targets than brook trout, probably because they reside in generally bigger habitats with more food options. Brookies are often found in small waters with sparse habitat. This means that anything that looks like food will get a look. Browns have the luxury of being more selective. 

How Are Trout and Char Different?

There’s actually very little difference between trout and char, at least in terms of habitat. In many waters, they have evolved together over thousands of years. They can be tough to tell apart, however. The best way to do so? Trout have light bodies with dark spots. Char have darker bodies with light spots. There are other methods, but this is the most dependable. 

How Big Do Brown Trout Get?

Browns in fresh water can get very big. The world-record brown was caught in New Zealand and measured 44 inches long. 

How Big Do Brook Trout Get?

In their native habitat in Labrador, Quebec and Ontario, brook trout can grow to six or eight pounds and measure 24 to 26 inches. The world-record brookie was caught in the Nipigon River in Ontario in 1915. It measured over 31 inches long and weighed more than 14 pounds.

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