There has been a recent shift from mark-recapture to sonar to estimate Canadian border escapement. Alaska Department of Fish and Game and the Canadian Department of Fisheries and Oceans biologists found that the Eagle test fishery (gillnet) age composition is significantly different from that estimated from mark-recapture (fish wheel) such that the two data sets are not comparable. This finding highlights the need to 1) develop a Gold Standard for monitoring the age composition of the escapement and 2) to develop a conversion factor such that past and future age data are consistent and comparable through time. These data have implications for the development of brood tables and run size projections.
There are now three years of paired data when both test fishery and fish wheel are operated. The development of a conversion factor and the determination of appropriate sampling methods would be improved with additional years of paired data. This project would allow the comparison of historically operated fish wheel sampling data with sonar test fishing data and other concurrent sampling programs to help determine the relationship between sample composition and run composition. This will also help determine which sampling programs will be most useful in characterizing the ASL and genetic composition of Canadian-origin fish. Due to biases associated with nets, fishwheels, and other sample methods, its desirable to compare test fishery (gillnet) data collected at Eagle with fishwheels, carcass sampling and weir data. It is anticipated that this program will be used to work out potential sources of gear bias as well as assist with the finalization of previous run reconstruction tables which are based on ASL data to make the data set consistent through time. This program will also allow the comparison of ASL composition of past runs to the run composition with the mesh size restrictions.