Why would a fish biologist use an imaging sonar system to count fish?
The Fraser River in British Columbia, Canada, is home to the largest grouping of Pacific salmon stocks in the world, over 150 stocks at last count. All five Pacific salmon species are found in the Fraser River pink, coho, chum, Chinook, and sockeye and these species have enormous economic, social and cultural importance to Canadians, Americans, and First Nations on the west coast of North America. The most highly prized species sockeye salmon (Fig. 1) is the focus of intense management under the Pacific Salmon Treaty, which was signed and ratified by the federal governments of Canada and the United States in 1985. Fisheries managers first allocate a portion of returning sockeye salmon to meet annual escapement goals (the number of fish returning to their home stream to spawn to sustain each stock) and then the remaining fish are allocated to harvesting by First Nations, commercial and recreational fisheries. Reliable escapement data is a key requirement for effective management of sock
