Swimbladder cross sections and acoustic target strengths of 13 pollack and 2 saithe

Abstract

Data are presented on the swimbladder form and acoustic target strengths of each of 15 surface-adapted gadoids, 13 pollack (POLLACHIUS POLLACHIUS) and 2 saithe (POLLACHIUS VIRENS), of lengths from 31.5 to 44.5 cm. The swimbladder data consist in sagittal cross sections of the swimbladder, derived by shock-freezing of the whole fish and slicing with a microtome. The acoustic data consist in the dependence of the target strength on tilt angle for both dorsal and ventral aspects for each of four echo sounder frequencies, from 38 to 120 kHz. Possible uses of such data in acoustic modelling of swimbladder-bearing fish and in systematic studies of swimbladder morphometry are mentioned.