Bull trout (Salvelinus confluentus)
Retain functioning riparian areas around critical habitats.
Minimize problems associated with access.
When considering a proposed WHA, consult with regional fisheries section heads over staging, spawning and over-wintering congregations or where obstructions to upstream migration cause bull trout to collect.
A congregation is defined as a significant portion of a run. A significant portion will be between 20 and 80% of the adult population of a run, depending on professional judgment. True congregations will be intuitively obvious at critical times of the year. They should be based on a ground survey or aerial redd count that identifies a significant portion of the run accumulating at a specific location/habitat. A fairly quick survey of a system that looks at key probable habitats but only identifies a `significant' congregation at one or two locations should be sufficient. For example, in a river system you may find a few individuals or pairs of bull trout scattered over a long stretch of river but also find a school of 20+ individuals at a barrier falls or likely spawning area. In this case, it is the 20+ concentration that is considered significant.
The WHA should extend 500 m around the congregation on all sides. Where the congregation is occupying a single pool, the WHA will be more or less circular with a radius of 500 m. Where the congregation is spread out along a stream reach, the WHA can be elongated up to 2 km.
Avoid creating access to the congregation.
Maintain stream channel integrity, groundwater flow, substrate composition, cover and natural temperature regimes.
These measures must be applied within a WHA approved for the species.
Harvesting and road development adjacent to WHAs may increase storm volume and peak flows in streams. In addition, poaching is a serious problem in remote areas and roads provide access to anglers and poachers.
Minimize cattle access to aquatic and riparian habitats in areas occupied by bull trout.
Minimize road development within 500 m of stream and stream crossings.
Ensure that sedimentation and erosion are controlled.
Minimize upstream and upslope impacts to prevent siltation, temperature and hydrologic problems in reaches supporting bull trout.
Ensure LWD recruitment over time.
Avoid development of recreational trails, facilities or structures immediately adjacent to WHAs.
Retain habitat in an interconnected mosaic that prevents fragmentation and the subsequent isolation of populations. Except for populations upstream of migration barriers, subpopulations that occur in the same watershed likely exchange individuals and re-establish each other following catastrophic events. Studies on these clusters of subpopulations (metapopulations), indicate that the likelihood of persistence decreases as local populations become isolated from each other through the creation of barriers to movement. Obstructions to bull trout movement can be fairly obvious (e.g., jump height and water velocity), more subtle, such as degraded habitats (e.g., water temperatures and pool depth), or in-stream structures such as culverts. The risk of extirpation rises whenever migration barriers increase habitat fragmentation.
Wildlife habitat areas will provide some protection of critical concentrations, such as spawning sites, but they cannot address all aspects of the bull trout's life history requirements. Because this species is especially sensitive to overfishing and habitat degradation and some life forms migrate and use a variety of sparsely distributed habitats, its requirements must be addressed at the forest level in order to effectively manage for populations.
The following recommendations are not mandatory, are not to be inferred as government direction and are not intended to have application across the entire planning area. Instead, they should be considered for areas upstream and upslope of the lowest reach occupied by bull trout, where 1) streams are sensitive to disturbance, 2) fry and juvenile densities are higher than average based on literature, 3) habitat is high quality, or 4) population or habitat is regionally or provincially significant. These recommendations are based on the best technical information on the species at this time and some or all of them should be considered for application in localized portions of a planning area where the planning table intends to propose a conservation objective for the species. Planning tables are expected to consider these recommendations along with other proposed timber and non-timber resource objectives. If necessary to accommodate other objectives, planning tables should consider restricting the distribution of the recommended management practices, rather than modifying the practices themselves.
To prevent habitat fragmentation and degradation by minimizing access and maintaining natural channel morphology, substrate composition, cover and temperatures in watersheds where bull trout occur.
- sub-basins where a significant number of mass wasting events have occurred (i.e., more than one landslide/km2 and more than two mass wasting events entering the mainstem river)
- sub-basins where there is either high road density (i.e., more than 150 m of road/km2) or high stream density (i.e., more than one km of stream/km2) on unstable or erodible soils
- sub-basins with a significant number of stream crossings (i.e., more than 0.6/km2 in the interior or more than 1.4/km2 on the coast)