Scaring lines—An innovative and flexible solution for the Nephrops fishery (FLEXSELECT)

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The FLEXSELECT project set out to develop and demonstrate a simple and efficient system that could be quickly coupled to any existing demersal trawl to reduce the catch of fish. For example, to improve the species selection in the Danish mixed demersal trawl fishery targeting Norway lobster. The principle of FLEXSELECT is the same as what is currently used today to herd fish into the path of the trawl, however, the scaring lines are mounted in a way that instead of herding the fish into the path of the trawl, they direct unwanted fish away from the trawl’s path so that they do not enter the trawl itself.

This approach is somewhat different to most of the work that has been carried out to improve species and size selection in demersal trawls. A majority of the work has concentrated around different solution in and around the codend itself, as opposed to the introduction of simple devices ahead of the trawl that are capable of altering the catch composition.

The development and testing of the FLEXSELECT scaring lines took place on board R/V Havfisken in 2016 and 2017 and aimed at establishing the design principle, testing different design parameters, and developing a coupling system that makes it easy to assemble and disassemble to ensure maximum flexibility. Based on the results from the first trials, commercial testing was carried out together with the commercial fishing vessel FN 436 Tove Kajgaard. As part of the commercial trials, further design parameters were tested, a final prototype was produced and tested under commercial conditions.

The results obtained show that FLEXSELECT is a simple, cheap and effective selective device that can reduce the catch of fish bycatch, especially roundfish, in the mixed demersal trawl fishery targeting Norway lobster. Moreover, the device has the advantage to be applicable only when required, at the haul-by-haul level (e.g. in response to the availability of quotas or bycatch hotspots), and it can be easily adjusted to fit any trawl size. Furthermore, its applicability extends to any demersal trawl fishery wanting to reduced unwanted catches of fish.

The project was completed during the period 07-09-2016 until 23-08-2019 by DTU Aqua with participation from The Danish Fishermen’s Association.

This report provides and overview of the work undertaken during the project and presents the results from the individual trials. Furthermore, the report highlights some of the challenges which arose during the project and how these can be addressed in the future.
Original languageEnglish
PublisherDTU Aqua
Number of pages44
ISBN (Electronic)978-87-7481-275-3
Publication statusPublished - 2019
SeriesDTU Aqua-rapport


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