Norwegian company Scanmar is launching its latest innovation - a hydrophone with noise measurement.
The new hydrophone includes features such as interpreting noise from the vessel in real-time, and how this impacts on various fisheries. The hydrophone also estimates the scare factor, based on fish species’ different hearing curves. These hearing curves are the result of extensive research from across the world.
The new tool will give the skipper on the bridge valuable information during fishing with trawl or seine, for example, if the noise coming from the vessel is above a certain threshold or if it has a large scare effect on the fish. It’s a well-known fact that sound carries well under water, and according to Scanmar R&D director Per Kolbjørn Soglo, you must go deeper than 400-500m before the noise from the vessel stops affecting herring, for example.
Scare factor
Noise from the propeller and the vessel ploughing forward is a known factor for most skippers, who know how easily fish get frightened by sounds in the water - some species to a higher, other to a smaller degree. Naturally the scare factor is of great concern when trawling down to 100-200m depths (in some cases even deeper) and when searching for schools and deploying seine nets.
Having the new noise detection system installed gives the skipper a continuous measurement of the vessel’s noise levels and enables him to make small adjustments, such as reducing trawl speed, modifying propeller angle or making other adjustments to reduce the noise to acceptable levels that do not scare the fish. With ease the skipper can glance at the monitor and see the scare factor of different fish species, what the noise means, and experiment and figure out what levels are optimal for the particular fishery.
Per Kolbjørn Soglo says that no one has ever linked noise to fish behaviour before, in the way it has been done with this new product.
The noise hydrophone has completed its final ocean trail with Havfisk’s trawls and passed with flying colours. The expected market release is Q2 2015, although hydrophones are already being mounted on docked vessels. The noise hydrophone is the same size and has the same mounting procedure as regular hydrophones and the vessel must be docked for hull installation.
Despite the hydrophone software still being in the final development stage, Scanmar already reports great interest amongst skippers around the world, and says that this shows how significant such an instrument will be for the industry.
