| Abstract/Description or Keywords |
Since 1999, the Moricetown Salmon Tagging Project 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 Skeena Fish and Wildlife Branch of the British Columbia Ministry of Forests, Lands and Natural Resource Operations, the Pacific Salmon Foundation, and the British Columbia Living Rivers Trust Fund. 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 2012, steelhead catch at both the campground and at the canyon were respectable in comparison to the earlier years of this study, but somewhat lower than the highest year (i.e. 2010) as a result of fewer steelhead arriving and reduced sampling effort due to budget constraints. Of the 2890 steelhead that were examined at the canyon, 125 were recaptures of the 1196 steelhead tagged at the campground. The stratified abundance estimates for steelhead arriving at Moricetown from July 30th to October 18th, with a 2.5% correction for tag loss, were 21 926 (95% C.I. 16 456 – 27 395) using Maximum Likelihood Darroch and 22 931 using Schaefer methods. The stratified abundance estimates are provided to identify potential inaccuracies, bias and misleading precision of an estimate of 27 465 steelhead (95% C.I. 23 709 – 33 167) using the pooled Petersen estimate for inter-annual comparisons of steelhead abundance to previous years. In general, the pooled Petersen estimate for steelhead abundance in 2012 was significantly lower than the highest and most precise estimate of steelhead arriving at Moricetown in 2010 (i.e. 41 140 with 95% C.I.: 38 058 – 44 934) and significantly higher than estimates made for 2003, 2004, 2005, 2006, and 2011. Some extrapolations of the pooled-Petersen estimates for 2012 have also been included to represent 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 dip net 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 how the range of adjustments can modify the estimates of steelhead abundance upstream of Moricetown. The corrected pooled-Petersen estimates for steelhead migrating upstream of Moricetown are 24 178 with 10% fallback, 21 431 with 20% fallback, and 16 479 with 40% fallback of steelhead that arrived at the campground and are predicted not to have migrated past the canyon as of October 18th in 2012. In conclusion, the Wet’suwet’en Fisheries office and field staff have had another very successful year conducting the 2012 Morictown Steelhead tagging project in cooperation with Fisheries and Oceans Canada and the Ministry of Forest, Land and Natural Resource Operations. Their interest and dedication toward protecting the Bulkley/Morice river steelhead, efforts to improve their fish handling methodologies, upgrades to the electronic data entry system, improvements to data quality, statistically useful results, and overall support for this program are commendable and clearly show many advantages for this project to continue for at least a few more cycles of steelhead generations. |
