Bull trout
A char, not a true trout, that needs the coldest, cleanest water in the mountains, so finding one is itself a kind of water-quality report.
Bull trout at a glance
Salvelinus confluentus BULL TROWT; Salvelinus confluentus is sal-vuh-LY-nus kon-floo-EN-tus
- Type
- Fish · char
- Diet
- Carnivore
- Size
- Most bull trout run 12 to 20 inches, but in the right lake system they can top 30 inches and 20 pounds, about the weight of a full car tire, the biggest char in these mountains.
- Lifespan
- Can live over 20 years, longer than most trout and salmon in these parks, in part because bull trout that survive to adulthood keep growing slowly for life.
- Conservation
- Threatened (U.S. Endangered Species Act, coterminous U.S. population, since 1999); Vulnerable (IUCN)
Eats whitefish, sculpin, other trout, insects (as young fish)
Young bull trout eat insects like any small stream fish, but adults become serious predators, ambushing whitefish, sculpin, and even other trout in the coldest pools and side channels they can find.
Should you worry?
Bull trout are completely harmless to people. Because they're federally threatened, any bull trout caught in park waters must be released immediately. Keep it in the water as much as possible and let it go quickly rather than handling it on a bank or dock.
Most fish in a mountain stream will take whatever water they’re given. A bull trout won’t. It needs some of the coldest, cleanest water in the whole system, cold enough that biologists treat its presence as a kind of instrument reading: find a bull trout holding in a pool, and you’ve just learned something true about that pool that no thermometer alone could tell you as fast.
That pickiness is also why the species is in trouble. Coastal-Puget Sound bull trout, the population living in North Cascades and Olympic, were listed as threatened in 1999, worn down by logging that warmed streams, dams that blocked cold headwater habitat, overharvest, and interbreeding with hatchery fish that carried none of the traits built for surviving in ice water. A char, not a true trout, pale-spotted on a dark body instead of the other way around, bull trout also turned out to be serious predators once grown, ambushing whitefish and sculpin and occasionally other trout in exactly the coldwater pockets nothing else could tolerate. In the right lake system one can reach 30 inches and 20 pounds. Washington’s state record stands at 22.5 pounds.
None of that size or predatory habit changes what happens if a kid or an adult hooks one. A bull trout caught anywhere in these parks goes back in the water immediately, no photo on the dock, no measuring on dry ground, just a quick release before it’s out of the current long enough to matter. The fish that needed the coldest water in the range to survive this long doesn’t get to spend any of it out of the stream.
Did you know?
- Bull trout aren't actually "true" trout at all. Like the brook trout, they're a char, a cousin group with paler spots on a darker body, the opposite pattern from most trout.
- Adult bull trout mostly eat other fish, including whitefish, sculpin, and sometimes even other trout, unusual for a stream fish this far up in the cold headwaters.
- Washington's state-record bull trout weighed 22.5 pounds, caught from a lake system big enough and cold enough to let one grow that large.
Common questions
Why is the bull trout called "a thermometer with fins"?
Because it needs some of the coldest water of any fish in these mountains. If a stream is cold and clean enough for bull trout to live and spawn in, that's a good sign for the whole stream.
Is a bull trout a real trout?
Not technically. It's a char, a close cousin of trout and salmon, the same family group as the brook trout, with pale spots on a dark body instead of the other way around.
Can I keep a bull trout I catch?
No. Bull trout are federally threatened, so any one caught in park waters must be released right away. Keep it in the water as much as you can.
How big do bull trout get?
Most run 12 to 20 inches, but in a good lake system they can pass 30 inches and 20 pounds. Washington's state record is 22.5 pounds.