ECOS Guide to the Ecology of the Northern Rockies

Name:  Salvelinus Confluentus - Bull Trout(or Bull Charr)

Family: Salmonidae (Trout and Salmon)

Order: Salmoniformes (Salmon/Trout/Pike)

Class: Osteichthyes (Bony Fishes)

Abundance: 

Origin: Native

Active Season: Year Round

Colors:

General Description: Adults 24” to 37”, however some bull trout remain in small streams and only reach a length of about 11”. Body somewhat rounded slightly compressed. Color olive-green to black, back has pale yellow spots, side has red or orange spots. Belly whitish. Head wide and mouth large. Teeth on jaws. Pectoral and pelvic fins have white leading edges, not offset with black lines (see brook trout). Caudal fin slight forked. Dorsal fin translucent with no black markings.

Similar Species:

• Brook trout (Salvelinus fontinalis) have wavy lines on their back and black markings on their dorsal fins. The white leading edges on the pectoral and pelvic fins of brook trout is set off by a black line. The saying “no black, put it back” refers to the lack of black markings on the dorsal fin of bull trout and is meant as a comparison to brook trout.
• Lake trout (Salvelinus namaycush) have a much more deeply forked caudal fin and spots on the side are not orange or red. Lake trout are found in deep cold lakes and reservoirs.
  

Life History: Sexually mature in four or five years. Spawn in fall in streams. Juveniles emerge in the spring (February to April, depending on local conditions) and remain in their natal stream for one to three years. Some juveniles never leave these streams and mature and spawn there. Other fish migrate to larger bodies of water (larger rivers or lakes) to feed and return to their natal stream to spawn after they mature.

Distribution: Occurs throughout northwest North America west of the Continental Divide. In the northern Rockies bull trout can be found in high mountain lakes and streams.

Habitat Description: Primarily large, coldwater streams and lakes, but also occur in smaller streams.

Feeding Habits: Juveniles feed on aquatic insects. Adults eat primarily other fish but have also been known to eat frongs, garter snakes, mice and duclkings.

Did You Know: Bull trout are listed as threatened under the Endangered Species Act because population declines have occurred through the species’ range. Bull trout hybridize with non-native brook trout but hybridization rarely proceeds beyond the first generation. Brook trout probably compete with bull trout and because they mature at age one or two, their populations can grow faster than bull trout populations. In Canada, this species’ common name is the bull charr. Charr have dark bodies with light spots. Trout (for example westslope cutthroat trout or rainbow trout) have light bodies with dark spots. The common name in Canada makes more sense.

Glossary:

• Caudal fin: tail fin.
• Dorsal fin: a fin along the midline of the back, usually midway between the head and tail fin.
• Pectoral fins: the forward or uppermost paired fins on each side just behind the head.
• Pelvic fin: the paired fins on the lower body behind or below the pectoral fins.
• Natal stream: stream in which a fish was born.
  

Keywords:  Bull trout, Salvelinus, charr, salmonid

References:

Holton, G. D. and H. E. Johnson. 2003. A Field Guide to Montana Fishes, Third Edition. Montana Fish, Wildlife & Parks, Helena, MT.

Contributor:

Andrew Whiteley