The assessment of the daily abundance of Fraser River Sockeye and Pink salmon are based on hydro-acoustic data collected at Mission. Marine test fishing catches are used as early indicators of relative abundances in marine areas, but need to be extrapolated using an expansion line (1/catchability) to derive abundance estimates, but because of the high variability in marine test fishing catchability and the uncertainty in the expansion line, the resulting abundance estimates will vary widely.
An important factor that impacts catchability is local tides and currents; however, it has not been possible to explain some of the variability in catchability data using published tide and current information, as it does not take into account the real-time localized tidal impact and currents on salmon migration behaviour at specific test fishing locations.
This project aims to collect local real-time tide and current information over three years and evaluate its usefulness to improve abundance estimates derived from marine test fishery data. The collection of these data will augment other test fishery data used to assess run sizes.