Water Stewardship Information Sources
| ID | 2667 |
|---|---|
| Citation | Saimoto, Ron S.; Saimoto, Regina K. (2011) Summary report of Bulkley/Morice River steelhead data collected by the Wet’suwet’en Fisheries during the 2010 Moricetown Tagging Project, SKR Consultants Ltd. Prepared for Ministry of Forests, Lands and Natural Resource Operations, Pacific Salmon Foundation, and The Living Rivers Trust Fund. |
| Organization | Ministry of Forests, Lands and Natural Resource Operations; Pacific Salmon Foundation; The Living Rivers Trust Fund |
| URL | http://salmonwatersheds.ca/library/lib_b_526/ |
| Abstract/Description or Keywords | Since 1999, the Moricetown Salmon Tagging Program has been conducted on the Bulkley River by the Wet’suwet’en Fisheries and Fisheries and Oceans Canada, with the inclusion of data collection for steelhead (Oncorhynchus mykiss) under assistance from the Ministry of Environment, Skeena Watershed Initiative, the Pacific Salmon Foundation, and the British Columbia Living Rivers Trust Fund. Since the initiation of this program, the annually collected steelhead data have gained value and importance as the sampling experience and program have developed. This mark and recapture project has involved sampling by beach seine for tag application immediately downstream of Moricetown Canyon (i.e. referred to as “campground”) and re-sampling by dip net at the base of Moricetown Falls and fishway (i.e. referred to as “canyon”). In 2010, steelhead catch at both the campground (N=3510) and at the canyon (N=6323) reached record levels for the second consecutive year. Based on the recapture of 452 steelhead of the 2946 tags that were applied at the campground and the 6323 steelhead that were re-sampled at the canyon, the stratified abundance estimates for steelhead arriving at Moricetown were 33 047 (95% C.I. 29 599 – 36 495) using Maximum Likelihood Darroch (ML Darroch) and 37 851 using Schaeffer estimates, compared to 41 140 (95% C.I. 38 058 – 44 934) using the pooled Petersen estimate that has commonly been referred to for inter-annual comparisons of steelhead abundance in previous years. Although the ML Darroch estimate of 33 047 steelhead may have less bias than the pooled-Petersen estimate due to the heterogeneity of catchability identified among temporal strata in the 2010 data, it is also not as precise and may be an under-estimate. Excluding pooled-Petersen estimates for 1999 and 2000 which had few recaptures and poor accuracy (>50% error), the estimate of 41 140 steelhead arriving at Moricetown Canyon in 2010 is 50% greater than the next highest abundance recorded since 2001 (i.e. 27 484 in 2008). Some manipulations of the pooled-Petersen estimates have been included to present the number of steelhead that actually migrated upstream of Moricetown Canyon as of the final date of sampling at the canyon in comparison to the estimate of steelhead that arrived at the campground. Based on the 2009 acoustic telemetry study estimating 34% of steelhead that arrived at the campground but did not migrate upstream of Moricetown Canyon while the dipnet fishery was operating (Welch et al. 2009 & 2010), a range of rates of fallback (i.e. 10%, 20% and 40%), have been used as examples of the range of adjustments suggested to estimate steelhead abundance upstream of Moricetown. The corrected pooled-Petersen estimates for steelhead migrating upstream of Moricetown are suspected to be 37 026 with 10% fallback, 32 912 with 20% fallback, and 24 684 with 40% fallback of steelhead that were tagged at the campground and predicted not to have migrated past the canyon as of October 22nd in 2010. Overall, the Wet’suwet’en Tagging Program continues to improve year after year and will hopefully progress with the commitment that it has had, in conjunction with some additional, consistent, base funding from applicable funding sources. A number of suggestions for additions and modifications to the project design and methodologies have been presented to improve the precision of the results, better identify the biases of the different abundance methods, limit the effects of handling on steelhead condition, and to develop tools and understanding that will make in-season results useful. Development and acceptance of an abundance estimate model that incorporates temporal stratification and accounts for the temporal heterogeneity of catchability into an in-season estimator of steelhead abundance appears to be the key to future use of this data for in-season forecasts of annual returns of this mix of Bulkley and Morice steelhead in comparison to historical records or possibly other indices such as the Tyee Test Fishery Steelhead Index. |
| Information Type | Report |
| Regional Watershed | Bulkley River |
| Sub-watershed if known | Morice River |
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| Comments | Main report entered separately in database. |
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