Coastal Cutthroat Trout as Sentinels of Lower Mainland Watershed ...

74. Cutthroat Nursery Habitat RestorationIn many cutthroat streams, habitat restoration of cutthroat nursery streams may be neededif natural processes have been degraded. Causes can be excessive flow withdrawals,obstructions to migration including flood boxes, isolation of off-channel habitats,curtailment of salmon carcasses for productivity, loss of summer rearing and overwinteringhabitats, past logging of banks, and channelization. To be most effective,habitat restoration should follow a strategy of (1) protecting existing high qualityhabitats, (2) restoring natural watershed processes, and (3) applying well-tested habitatrestoration techniques, which are summarized for cutthroat streams. Restoring degradedhabitats of a single small cutthroat stream per year would incrementally assure asubstantial net gain of prime cutthroat and coho nursery habitat over a few decades, aswell as garnering public education and support.5. Coastal Cutthroat Informational Gap ResearchSeveral key information gaps have been identified through this review. Some requiremanagement actions while others require applied research projects which are prioritizedas follows:• Due to genetic risks associated with hatchery culture of sea-run cutthroat trout,discrete populations with variable life histories need to be confirmed in the LowerFraser River and its major tributaries through life history profiling;• Wild-hatchery stock interactions, including hybrization, need to be quantified asaffected by the anadromous cutthroat and steelhead programs in the LowerMainland, and particularly in the Lower Fraser and its tributaries. Although thecollapse of major cutthroat stocks in Oregon and southern Washington wasassociated with poor near-shore marine conditions and land/water quality impacts,a large hatchery program was also considered a causative factor;• A workshop review of anadromous cutthroat hatchery practices is needed toprovide guidance on sound measures to minimize or eliminate wild-hatcherystock interactions, similar to the Ministry’s 1990 steelhead genetics workshop;• Age-specific densities and survivals of sea-run cutthroat trout under varyingconditions and productivities need to be confirmed, with a focus on refinement ofbenchmarks to be used for assessing underyearling and parr densities, andaccounting for differences in nursery stream productivity;• The effectiveness of special regulations on piscivorous cutthroat lake fisheriesneeds evaluation, since maximum size regulations are an option for improving thequality of several wild cutthroat lake fisheries; and• The incidence of sea-run versus resident forms needs to be quantified in a sampleof coastal streams because it is widely assumed that all coastal streams producethe sea-run form of cutthroat trout, which is unlikely.6. Sea-run Cutthroat Stock Conservation via Regional Index StreamsLong-term trend data on sea-run cutthroat stocks is available in other jurisdictions, but isweakly developed in British Columbia. Fisheries management to ensure conservationcannot be achieved without such trend data. Targets in the Lower Mainland Regionshould include periodic updating of index data, on adults, smolt and juvenile abundancesas well as an index of catch-effort, with a strong focus on establishing long-term trends: