Fisheries acoustics is used to monitor the largest fish and krill stocks in the world’s oceans and to study marine ecosystems. A modern fishery without acoustic tools for detection, inspection and monitoring of seabed, schools, and the catching process is unthinkable. New wideband echo sounders offer a new opportunity in this arena for Norwegian science and industry. Science and fishing vessels can not only observe the echo amplitude and density of fish under the vessel, but also utilize the backscattered echo spectrum from the organisms. For simplicity, we prefer to define this as the echo dialect of the objects, as for example, an echo from an individual herring is affected by body shape, swim bladder, body constituent and behavior, and is different from the mackerel “echo dialect". We propose that systematic experimental and in situ research can be used to understand and interpret the different echo dialects from fish and marine organisms. We will further expand on existing multifrequency methods for classification and target sizing by utilizing modern machine learning techniques. This will improve the accuracy of existing monitoring methods and help the fishing skipper to make good catch decisions. Further, direct optical observations from the trawl and use of active selection devises will reduce bycatch. For accurate verification of acoustic recordings, we need continuous optical information from the trawl cod end. This will be achieved with the Scantrol DeepVision system, here tested with active selection devices, and open/closing nets. Discrete samples may then be taken sequentially in deep water, such as in mesopelagic communities. Wideband technology has been miniaturized and can be installed in probes, bottom landers, and surface and underwater unmanned vehicles (drones). We will assess how these can improve scientific monitoring by increased adaptive sampling, and how drones can be used in fishing for forward-mapping and inspection prior to catching.
Project leader: Egil Ona