Fish and Aquatic Conservation

an artwork of a Bull trout

Fish illustration by Laury Zicari, USFWS, Retired

Bull trout

My Scientific Name

Salvelinus confluentus

By the Numbers

We are generally 12 to 20 inches in length, and weigh 4 pounds. Some of us that live in lakes, grow to more than two feet in length. The largest was more than 40 inches long and over 20 pounds!

How to Identify Me

I have an unusually large head and mouth for a fish my size; it’s how I got the name ‘bull trout.’ Brook trout and lake trout are my cousins, but my tail fins aren’t deeply-forked like theirs. My fins have white edges, and the top of my body is dark in color. I also have yellow, orange, or salmon-colored spots on our backs.

Why I Matter and What's Been Happening

My species is an excellent indicator of water quality, and we have the most specific habitat requirements of any fish in our (Salmonidae) family. So, when people restore and protect our habitat, water quality is improved in our rivers and lakes for other fish, animals, and people too!

My Status

Our populations are in decline and struggling throughout much of our range because we can’t find or reach our preferred habitats. We need cold, clean water and connected, complex habitats –think lots of riffles and pools, undercut banks and logs in the stream. We’re listed as a threatened species under the Endangered Species Act, but fortunately a lot of people are working together to help restore us.

did you know image
  • Bull trout are not really trout! They’re actually char, meaning they’re more closely related to brook trout and lake trout then they are rainbow trout or salmon.
  • For a long time people thought that bull trout and Dolly Varden trout were the same fish. Then scientists learned they were different species of char.
  • Bull trout require colder water than most salmonid species (salmon, rainbow trout, whitefish, brook and lake trout) and are mostly found in pristine rivers and lakes.
  • They need the 4Cs: Cold, Clean water, with Connected and Complex underwater habitat.
  • They also are good indicators of healthy rivers and lakes.
  • Some of the biggest threats to their survival are low flows, loss of shade cover along rivers, high water temperatures, pollution, blocked access to spawning grounds and invasive non-native species.
  • Some runs of bull trout are anadromous, meaning they spend part of their lives migrating to, from, and within the ocean, but spawn in freshwater.
  • Freshwater migration is important to maintaining healthy bull trout populations, too. They will swim considerable distances to spawn when habitat conditions allow.
  • Bull trout in Montana’s Flathead Lake have been known to migrate over 150 miles!
  • Bull trout are a popular sport fish where their populations are healthy enough to support fishing. They are very aggressive, and have even eaten other fish hooked by anglers.

a map of northwest region of USA, showing range of the Bull trout

Figure 1 – Bull trout are native to western North America, and can be found from Northern California to Montana. Credit: Alliance for the Wild Rockies.

More about Us image

a small bull trout swimming in the water

Small bull trout eat terrestrial and aquatic insects but prey on other fish as they grow larger. They eat whitefish, sculpins and other trout.

an interpretive sign that says Anglers you are in Bull Trout Country! Then a big nice picture of Bull trout with message.Be sure you identify them. They may not be keptand possession can result in a $200.00 fine. If you don't know, be safe and let it go!

Bull trout are a threatened species, so if they’re hooked by anglers they need to be released unharmed.

four large bull trout swimming underwater

Large bull trout are piscivorous, meaning they’re fish predators.

a looking nice small waterfall with a bull trout resting underwater next to the trees in the woods

Bull trout need the four Cs: Cold, Clean, Connected, Complex aquatic habitat.

two scientists helping each other, one is holding a bull trout upside down while the other is placing radio tag inside its body before releasing it to the water

Scientists place radio tags inside migrating bull trout to track their movements and learn more about their preferred habitat. This information will help people restore bull trout and the places they need to live.

Learn more about Bull trout!

How you can help statement: Get to know me, if you don’t already. Help make me visible to people who don’t have the chance to see me by sharing your stories about me. Get involved in efforts to help conserve my habitat and maintain my populations into the future.