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AWR Special Report #9
A
Special Report on the Bull Trout
(Salvelinus Confluentus)
Rebuilding Native Fisheries
Economic and Spiritual Values
 The
native fish of the Northwest and Northern Rockies have immense spiritual
and economic value. In Montana, Idaho, Washington, and Oregon, fishing
brings in well over $1 billion a year, and tens of thousands of jobs.
Moreover, these fish are indicators of our quality of life. Their very
presence indicates that our landscape is still resilient. It is our duty
to rebuild our native fisheries so that future generations will enjoy
completely healthy river systems and large spawning runs of adult trout
and salmon. Rebuilding native fisheries will require an ecosystem approach
that takes a holistic view of entire watersheds and genetic linkages among
drainages.
Metapopulations
Recent scientific work in the fields of conservation biology and genetics
has provided new insights into bull trout viability. Isolated populations
of bull trout face serious genetic risks and are unlikely to persist.
Researchers have concluded that restoration of metapopulations (a collection
of connected subpopulations) of bull trout throughout their range is essential
to the persistence of the species. A key element of this strategy is recovery
of migratory bull trout. Thus, the issue of fish passage between migratory
corridors and spawning tributaries is crucial. Connectivity is the key
to recovery of bull trout.
Habitat Rehabilitation
Bringing back bull trout and other salmonids means bringing back their
habitat. Tens of thousands of miles of logging and mining roads cut through
their range, unleashing a never ending torrent of fine sediments, destroying
spawning gravels and smothering eggs. These roads also provide ready access
for poachers who are decimating spawning fish. Likewise, many grazing
allotments allow cattle to trample streambanks and streambeds, causing
erosion and sedimentation and loss of riparian vegetation essential to
maintaining low stream temperatures. Small irrigation dams unnecessarily
block migrations. Improperly placed culverts block off spawning habitat
on hundreds of Forest Service roads. An aggressive campaign of habitat
rehabilitation is necessary to remove roads, migration blockages, and
fence cattle out of streamside areas. Buffer zones are needed in key watersheds.
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Key Habitat Standards
for Bull Trout
The following
measures are needed to halt the decline of bull trout and begin
the long job of recovery:
- Protection
of roadless area watersheds by removing them from the scheduled
timber and grazing landbases.
- Protection
of riparian buffer areas (includes the stream and the area on
either side of the stream) at least 300 feet from the outer edge
of the flood plain.
- Water temperature
standards in all current and historic spawning, rearing and migratory
corridor habitats should not exceed 6-8 C for spawning and 10-12
C for rearing habitat, and 12 C in migratory stream corridors.
- Sediment
Delivery: less than 20% over natural from all anthropogenic sources
in bull trout watersheds.
- Fine Sediment
(spawning substrate): limit stream surface fine sediment (
<6.4mm
in diameter) to less than 20% in spawning habitat.
- Cobble Embeddedness
(rearing habitat):limit stream cobble embeddedness in summer rearing
habitat to less than 30% and less than 25% in winter rearing habitat.
- Develop Habitat
Standards for channel morphology including large woody debris,
pool frequency, and volume, and residual pool volumes.
- Bank Stability:all
streams should average greater than or equal to 90% stream stability
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Trout Habitat in the Northwest>
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