World first « Forward-Backward Sonar » for bottom trawlers confirms its efficiency

Following its very successful use on pelagic fleets, SeapiX 3D volumic sonar once again demonstrates its unique performance for bottom trawling operations.

Near bottom fish detection is the most difficult capability to provides skippers, due to bottom backscattering level that reduces sensitivity of fishery acoustic devices.

The classic paradigm is to operate low frequency sounder in order to get enough range for bottom operations (usually a 38Khz or 50Khz sounder, split beam 7°). However, when doing so, the beam opening dramatically reduces the capability to discriminate individuals located inside bottom gear layer.

Alaska or North Europe fisheries dedicated to bottom species now face concerns relating to quantitative evaluation as well as species discrimination. Indeed, whatever the density of biomass, classic sounders show about the same echogram.

Comparing this to SeapiX technology, already equipping 27 bottom trawlers, skippers have clearly proven how “Dual Multibeam” technology is capable of providing more realistic assessment of near bottom biomass. This is the benefit of a “Volumic resolution” (acoustic pixel) of only 0,6 m3 compared to the 6m3 usually offered by sounders. This volumic resolution, 10 times higher than traditional sounders, also provides capability to reach individuals closer to the bottom line.

This furthermore makes SeapiX capable of providing skippers with a fish detection that offers the same resolution and discrimination quality from surface and up to 400m depth whatever the species;  Mackerel, Bleu whiting, Cod, Tuna, Shrimps…SeapiX technology covers all species at all ranges.

It is for that purpose that David, owner of new “F/V AUDACIOUS” (UK), has chosen SeapiX for its new bottom trawler. After being operated for 9 months on the vessel, it was demonstrated that SeapiX, thanks to its high volumic resolution, is capable to detect about all individuals located inside a 5 ftm bottom layer.

“Facing a mix of 3 species all the time, I wish to target the fishing areas where there are the least different species possible. After calibrating the species within SeapiX, I get a clear species discrimination with up to 80% true real time classification. This truly helps me in the precise targeting of shoals.” says David.

An additional crucial feature for skippers is the understanding of near bottom biomass position and behavior. SeapiX sonar provides unparallel “Forward” looking capability, but also similar capability to follow bottom fish “backward”, behind vessels. An extremely interesting feature that improves catch ability, whatever the fish behavior.

Howard, skipper of the “F/V Northern Patriot” (USA) at Trident Seafood, particularly enjoy all 3D indications provided by SeapiX (bottom profile/bathymetry, hardness, position of shoal, type of fish…) to anticipate maneuvering in order to precisely target his catch and avoid the waste and discard of unwanted fish.

“I really like being able to use all 4 swaths, it is truly helping when the shoals are in front and beside the vessel. I can see if they are laying directly under the boat or off to one side”, Howard says.

Compared to other sonars dedicated to bottom trawlers, SeapiX provides extremely clear and defined pictures of bottom fish at more than 45° in front of the vessel, but also at more than 45° behind the vessel.