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Bull trout and juvenile coho
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River Caretakers
Bull Trout
Salvelinus confluentus
Northwest streams and lakes are like the Serengeti
of Africa and the depths of the Pacific, as there's always a top
predator who needs to eat. Predators are important to all ecosystems
for they help to keep companion species (their prey) healthy and
strong. The piscivorous bull trout is one such caretaker in the
waters of North Cascades. It recycles the energy of the old and
sick, while also feeding on the numerous young fish that inhabit
mountainous streams and lakes. In salmonids, adult females can lay
thousands of eggs of which only a fraction mature into adults.
The bull trout is a char, a close relative to the well-known Pacific
salmon subgroup which include chinook, coho, sockeye, pink, chum,
steelhead, and cutthroat. Char sport light spots on their dark backs,
unlike the Pacific salmon which have dark spots on their light backs.
Another important factor which distinguishes this threatened* salmonid
is its dependency on very cold water, especially for spawning. This
necessity isn't surprising since one of its closer relatives is
the arctic char. Rarely does one find the bull trout spawning anywhere
but in the cold, mountain reaches of rivers in the Northwest, where
water temperatures are typically below 48 degrees Fahrenheit.
Two challenges for bull trout are the removal of forests from mountains
and riversides and the introduction of exotic brook trout. Taking
trees from steep slopes often causes erosion. The destruction of
the riparian zone results in warm water. The ability of brook trout
to interbreed with bull trout threatens the genetic integrity of
the native fish. Brook trout also compete with bull trout for food
and space.
See how well you can design an ideal habitat for bull trout in
Reach for the Fish.
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Critical
Thinking: 