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AWR
Special Report #9
A
Special Report on the Bull Trout
(Salvelinus Confluentus)
Introduction
There's trouble in the waters of the U.S. Northern Rockies
and Northwest states. Long known as the home of America's finest blue-ribbon
fishing streams, its native trout are declining at an alarming pace. A
coherent plan of action is urgently needed to prevent the disappearance
of native stocks of bull trout. The Bull Trout (Salvelinus confluentus)
is the NorthwestÚs largest native migratory trout. An average adult weighs
five pounds. The U.S. record came from IdahoÚs Lake Pend Oreille, weighing
in at a whopping 33 pounds! Bull trout are also known for their tremendous
spawning journeys of up to 175 miles. Historical accounts tell of thousands
of spawning trout in virtually every mountain stream, and bull trout also
played a significant role in Native American culture. Despite this rich
legacy, our native trout are now gone from most of their range and the
last strongholds are now threatened.
Indicator Species
Bull trout depend on very clean, cold water and therefore are a prime
indicator of the health of forest ecosystems and watersheds. Extremely
sensitive to human-caused changes to their environment, bull trout are
a monitor of our own quality of life. Bull trout are less tolerant of
disturbances to their habitat than are other salmonids. Protection of
bull trout will accordingly also protect the habitat of numerous other
species, while maintaining high water quality.
Life History
The bull trout is a char that is taxonomically separate species from its
coastal relative Dolly Varden (Salvelinus malma), although they share
similar life histories. Four distinct patterns have been identified: resident,
fluvial, adfluvial, and anadromous- the latter reported only near Puget
Sound in Washington where anadromous bull trout grow large in the salt
water and then migrate to mountain tributaries to spawn. More common is
the inland migratory strategy. Adfluvial bull trout grow to adulthood
in lakes and migrate to streams for spawning. Fluvial bull trout follow
the same pattern only they grow large in rivers. Resident bull trout,
isolated by blockages to migration and damaged habitat, spend their entire
life in the same body of water. Spawning maturity occurs at four to six
years. Unlike salmon, spawning adults survive to spawn again every two
or three years.
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