WHALE COUNTING AND FISH SCHOOL BIOMASS APPRAISAL BY TWO NEW OMNI-DIRECTIONAL FISHERY SONARS

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Acoustic methods using omni-directional, multi-beam fishery sonar have mainly been used for qualitative school counting in stock evaluations, while their potential in behavioral studies and quantitative measures both for schooling fish and whale detection and counting have been seriously underutilized. Rebuilding and focusing more on improved more accuracy, both for biomass measures for schools, but also more accurate target tracking algorithms may be useful additions also to data from scientific sonars, which are more designed for shorter range accurate 3D school imaging, but with limited target tracking capabilities. Each observation-platform tends to be more specialized, but with overlapping observation volumes. The suggested development on two existin g sonars will therefore fill important gaps defined for ecosystem investigations, namely integrated and simultaneous observations of predator and prey. For the fishing industry, more accurate, sustainable fishing can also be achieved through more reliabl e systems for school biomass estimation, identification and sizing. By catching the correct fish species, and the suitable school size for preventing net damage or partial release, this application should therefore be highly relevant for three of the NRC program sub structures, I: Marine ecosystems (MAROKO), IV: Fishery technology and responsible catch (FORKON), and V: Value adding under Methods, models and technology (MEMOTEK. Since modern fishing vessels now are regularly used in large scale ecosystem s urveys (ICES, 2007), there could be a very short way from development to regular use. The main idea of this proposal is therefore to significantly increase the accuracy of the scientific output from regular fishery sonars with new transceiver system, and through calibrations initiate the development of a prototype scientific post-processing system and a fishery skipper toolbox.