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![A tracing made by an echo sounder shows concentrations of Pacific ocean perchon the sea floor, as well as the otter trawl of another vessel sweeping over the bottom toward the fish fish7975.jpg A tracing made by an echo sounder shows concentrations of Pacific ocean perchon the sea floor, as well as the otter trawl of another vessel sweeping over the bottom toward the fish](/sites/default/files/styles/max_1300x1300/https/s3.amazonaws.com/s3-east-testmedia-noaa.woc.noaa.gov/dam/Photos/legacy/pl23_fish7975.jpg?itok=4iyVGlQ5)
Description
A tracing made by an echo sounder shows concentrations of Pacific ocean perchon the sea floor, as well as the otter trawl of another vessel sweeping over the bottom toward the fish. (Image credit: NOAA Central Library Historical Fisheries Collection; P. 420 of Our Changing Fisheries 1970 Centenary NMFS centenary volume)