Broadband method to identify pelagic fish species

Commissioned by the Pelagic Freezer-trawler Association (PFA), Wageningen Marine Research studies broadband technology to identify pelagic fish species such as herring and mackerel during fishing. Recording the echo as it resonates off the fish at different frequencies, researchers attempt to discern the various species. Based on multiple separate frequencies, the old approach allowed only for the distinction between fish with a swimming bladder (such as herring and horse mackerel) and those without (such as mackerel and sand eel). ‘The new broadband equipment enables us to measure even the tiniest acoustic differences between fish’, says researcher Benoît Bergès. Reflected echoes are analysed using algorithms. The resulting information is far more accurate than that recorded by the current acoustic measuring equipment, according to Bergès.

Landing less bycatch

The broadband technology has been extensively tested during various fishing expeditions in different areas throughout the year. These tests yielded a wealth of data. Analysing the data and developing algorithms will make this technology suitable for use in pelagic fisheries, says Bergès. Its purpose is to reduce the amount of undesired bycatch. ‘It is difficult for fishers to determine what fish inhabit the waters beneath their vessel. In the future, this broadband technology will enable them to accurately determine the number of different fish species beneath the ship. If the data shows a large number of undesired fish, the skipper may decide to refrain from fishing in that spot. Thus, fishers can be more selective, so they land less bycatch.