The results included broadband data (160-260 kHz) of single mackerel detected up to 100 meters from the fishing vessel

Breakthrough Sonar Tech Promises Smarter, More Sustainable Fishing

NORWAY
Friday, May 23, 2025, 00:10 (GMT + 9)

Norwegian Researchers Develop Real-Time Fish Sizing Tool to Boost Efficiency and Reduce Unwanted Catches

BERGEN – Norwegian scientists are on the cusp of revolutionizing commercial fishing with the development of a pioneering sonar technology designed to provide fishermen with real-time information on fish size before capture. This innovation holds significant promise for enhancing both the profitability of fishing operations and the sustainable management of marine resources.

Detail of the hydraulic piston that will provide with tilt for the transducer (left) and transducer inside the blister (right).

The project, spearheaded by the Institute of Marine Research (HI) and supported by FHF (the Norwegian Seafood Research Fund), has been rigorously testing broadband sonar during active commercial fishing. The core objective is to enable fishermen to estimate fish size before deploying their nets, thereby allowing them to avoid catching undersized or undesirable fish.

An EK80 sonar system with a 200-3C transducer was mounted on the lower keel of the F/V Libas during commercial mackerel fishing in UK waters in 2024. Detail of the pole and the transducer off the water during cruising. The transducer is mounted in a plate that is tilted by a hydraulic piston.

Currently, fishermen often only ascertain fish size once the catch is on board, leading to wasted time and resources on low-value or illegal catches. The new technology aims to provide this crucial data pre-capture, facilitating more informed decisions on where and when to fish.

Mackerel in more dense aggregations during daytime. In the left of the echogram it is possible to observe the noise from the Kaijo sonar, as yellow to green vertical lines. On the right half of the echogram Kaijo sonar was stopped and clean data obtained (threshold to -65 dB).

Early development faced hurdles, as the initial method for estimating fish size, based on analyzing individual fish echoes, proved more complex than anticipated due to the irregular shapes and internal structures of fish. However, the research team has since identified a promising alternative. By measuring the strength of the echo and the angle of the fish, they have successfully developed a method for making usable estimates of fish size, marking a significant step forward.

Though still in development, researchers are now much closer to creating a practical tool for the industry. The next steps involve fine-tuning the methods and conducting tests under even more realistic conditions. The technology is also envisioned to integrate with existing sonar systems, offering fishermen a comprehensive view of underwater populations. This ongoing development work, which also received financial contributions from the Institute of Marine Research (HI) itself and involved the Lie Group, is set to contribute significantly to a more efficient, profitable, and sustainable global fishing industry.

Rita Naustvik, representing FHF in this project, stated that the results will inform future research efforts.

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