The goals of this project are to utilize reliable, cost effective resistivity or sonar counting methods on select tributaries of the Fraser River to estimate escapements of Coho and/or Chinook salmon to a) improve estimate accuracy and b) determine precision of escapement estimates.
The project objectives are to:
1/ obtain a Middle Fraser Spring 1.3 Chinook tributary escapement estimate using a resistivity counter purchased through support of this proposal. This program will improve upon existing aerial escapement estimation and will evaluate the potential to develop an indicator stock and calibrate historic escapement estimates in a stream supporting a Spring 1.3 Chinook population;
2/ at the conclusion of the Spring 1.3 Chinook portion, relocate the resistivity counter to Barriere River to estimate Coho returns. This complex system of lakes and small tributaries is currently enumerated through visual methods however, estimate quality would benefit greatly from counts derived electronically as reliable visual counts can be difficult to obtain in this system;
3/ use PIT tagging methods to validate Bonaparte River Chinook and Coho fishway estimates. Currently the Bonaparte Chinook escapement trend does not track the escapement of other Fraser Spring Chinook 1.2 populations. There is concern that fish are able to move through the fishway and be counted then fall back undetected over the falls, and subsequently move back up river, and be counted again. A PIT tagging exercise will be conducted to investigate whether this is occurring and influencing escapement estimates for both Chinook and Coho;
4/ employ video technology to investigate co-migration of Chinook and Coho salmon with Pink salmon and other resident fish species through Bonaparte, Deadman, and Barriere rivers resistivity counters, as well as the selected Middle Fraser 1.3 Chinook system. Video validation will also be employed to determine counter efficiency and derive confidence limits around the resistivity estimates for each of our proposed systems; as well as,
5/ use SONAR (DIDSON/ARIS) to enumerate returns of Coho salmon to Spius Creek. Spius is thought to be a significant contributor to the Lower Thompson IFC CU, however it is a very difficult system to enumerate visually.