Image: FHF / FIS

Increased Catch and Reduced Bottom Impact with New Trawl Gear

A new trawl gear concept gave 20-40% more catch than standard rock hoppers. The gear is also designed to be gentler on the seabed, which can help the industry towards an even more efficient and environmentally friendly future.

In connection with the projects "Development of selection systems in cod trawls. National investment 2020–2023' and 'Gentle and efficient trawling for whitefish', a trip was carried out under the auspices of the Directorate of Fisheries. Both projects are a collaboration between the Institute of Marine Research, the University of Tromsø and SINTEF Ocean and have as their main goal the development of new selection devices for the trawl fishery and to reduce the bottom impact of trawl fishing.

Source: FHF

Less bottom impact

The voyage was carried out on board a commercial trawler at the end of November 2023. The main objective of the voyage was to test a new grate with a greater sorting capacity than the current grate sections and to test a new gear concept known as the Semi-Circle Spreading Gear (SCSG). This concept was first tested almost ten years ago, and although it has been used on research trips on several occasions (Grimaldo et al., 2013; Brinkhof et al., 2017), it has never been tested commercially.

Source: FHF -->

The gear tested on this trip was built in seven sections and had a total length of 31.2m. Due to the hydrodynamic design, the weight difference and what has previously been observed in undervane gearing, it is believed that the bottom impact from the SCSG is significantly lower than from a similar rockhopper gear. This will be investigated more thoroughly in the project "Gentle and effective trawling for whitefish", which will end in 2026.

Increased catch

Direct comparison of the catches taken with double trawls equipped with respectively a rockhopper gear and an SCSG showed that the latter can catch up to 50% more fish on average. At the same time, it may be that that difference was not exclusively due to SCSG and the results should be interpreted cautiously.

Previous tests carried out on board the research vessel Helmer Hanssen show that there are 20% fewer fish that go under the fishing line with SCSG compared to a normal gear (Brinkhof et al., 2017). The increased ability of SCSG to spread the trawl opening, reduction of fish that disappear under the fishing line and its stability is probably the reason for the increased catches.

Source: UiT

The introduction of such a gear could be an important milestone in the race towards more efficient and environmentally friendly trawl fishing.

Author / Source: Stine Falk-Petersen / FHF (Translated from the original in Norwegian)

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