The bull trout and Dolly Varden, although two distinct species, are often grouped together because it is so difficult to differentiate them. The bull trout can be identified by its olive green to brown body that has yellow or cream colored spots. It does not have the black spots on the dorsal fin that are seen on other trout and salmon or the dark wormy markings found on Eastern Brook Trout which is also a char. The bull trout is listed as a threatened species, and is present in three stocks through the Nooksack. The bull trout requires a pristine cold environment for spawning and rearing with abundant cover and a good supply of oxygen. Spawn from late summer through December.