Water Stewardship Information Sources
| ID | 1158 |
|---|---|
| Citation | Levy, DA and Parkinson, E. 2014. Independent Review of the Science and Management of Thompson River Steelhead. Prepared for Thompson Steelhead Technical Subcommittee c/o Cook's Ferry Indian Band, Spences Bridge, BC. |
| Organization | Thompson Steelhead Technical Subcommittee |
| URL | http://www.steelheadsociety.org/sites/default/files/thompson_study_march_2014.pdf |
| Abstract/Description or Keywords | In response to the decline in steelhead productivity that has been occurring since the early 1990's, the Thompson Steelhead Technical Subcommittee commissioned the present report to evaluate steelhead status, causes for the decline, effectiveness of management tools and prospects for recovery. The work was motivated by a strong desire among Thompson River First Nations to develop a sound conservation strategy that ensures long-term sustainability and a recovery of the traditional food, social and ceremonial fishery. Thompson River steelhead support a world-class recreational fishery which is managed by the Province of BC. DFO is intimately involved in the management process by developing salmon harvest regulations to mitigate commercial by-catch mortality. First Nations are largely outside of the management process and meaningful consultations have been absent to date. Science and management tools included harvest analysis, juvenile assessment, forecasting procedures, spawner enumeration and enhancement. Conservation thresholds place steelhead numbers in the conservation concern zone in most years. Habitat partitioning by parr (juvenile steelhead) results in discrete, fast-flowing areas of the Thompson River supporting most of the parr production. This habitat specialization makes it critical to maintain and enhance those features that promote steelhead growth and survival. Habitat threats include high water temperatures, bank instability, siltation, and water supply concerns including low flows and severe drought. Juvenile assessments undertaken by the B.C. Fish and Wildlife Branch, coupled with annual escapement monitoring, provide a basis for steelhead productivity analysis. Parr populations in the Thompson and its tributaries have shown only minor variations between years (between 217,000-307,000 parr) despite 4-fold differences in spawner density (approximately 500-2000 spawners). It follows that a freshwater population bottleneck may be suppressing the ability of the steelhead population to increase. Main factors affecting returns of Thompson steelhead to terminal areas are reduced ocean survival and by-catch interceptions in salmon net fisheries. Over the past 40 years with the adoption of more selective fishing methods, harvest mortality has dropped from around 70% to 10-20%. Over the same period, marine survivals have dropped so the net effect is a counterbalancing and steelhead productivity remains low. Ongoing interceptions in net fisheries have been mitigated to a partial extent but by-catch still remains an important mortality factor for Thompson steelhead. The magnitude of fisheries interception is difficult to measure accurately due to non-reporting and fatal injury. The scientific literature was reviewed to evaluate the interactions between migratory steelhead and resident rainbows, two forms of the same species. It has been shown that rainbows can produce steelhead and vice versa. The strong genetic overlap of the two forms means that rainbow trout dynamics and the relationship between steelhead and rainbow need to be considered during steelhead recovery programs. The relative productivity of marine and freshwater environments likely affects the proportion of rainbow and steelhead that are produced within a given watershed. Under presently low marine survival conditions it is possible that a greater proportion of Thompson steelhead residualize as rainbows. |
| Information Type | report |
| Regional Watershed | Thompson, Nicola |
| Sub-watershed if known | |
| Aquifer # | |
| Comments | |
| Project status | complete |
| Contact Name | David Levy |
| Contact Email | [email protected] |