Fig. 2. Schematic diagram showing the direction of surging and swaying accelerations recorded by a data logger placed on the left side of the body of a salmon, below the front edge of the dorsal fin (black bar). Data for surging acceleration were converted to body angles, as described in the text. Body angles while salmon were ascending are presented as positive values, and body angles while salmon were descending are presented as negative values. , angle of ascent/descent.