Trial of a New, Split-beam Echo Sounder

The first at-sea trial of a new, split-beam echo sounder, the SIMRAD ES380 system, is described following a review of the split-beam principle, outline of its realization in hardware and software, and description of adaptation of the commercial model for research purposes. Actual uses of the system during a cruise about Lofoten in March 1984 are described. These include direct in situ measurement of single-fish target strengths for several species, and investigation of avoidance reactions of fish under observation. Some planned features of the system are listed