Selective gear technology

Much discarding occurs because fishing gears are not selective enough. Selectivity work is ongoing to make fishing gear more selective so that bycatch and discards are reduced.

Many fisheries are based on a mixture of species and fish that are not wanted can be caught inadvertently.

Irish Sea selectivity trials

Seafish is managing a new project to trial four different highly selective TR2 gears operating on Irish Sea Nephrops grounds. The industry has come up with some promising designs which were trialled against standard gear and the Swedish Grid. For further information please contact Mike Montgomerie.

Nephrops grid trials in Scotland

Seafish has been running flume tank and sea trials on a new grid design aimed at reducing the numbers of discards in the Scottish trawl fishery for nephrops. The main aim of this project is to produce a grid that is similar in design to the Swedish grid, as efficient at reducing discards, and is suitable for fitting in the trawls used on Scottish vessels and easy to handle onboard. For further information please contact Mike Montgomerie.

The Scottish Government has classed the Flip Flap gear as highly selective. The Fathlie cod avoidance panel is now classed as a highly selective gear. Net Grid has been trialled by Cefas for <1.5% cod derogation. During part one of the Cefas trials a significant number of hauls were carried out in IVa. A 71% reduction in cod numbers was achieved. Awaiting corresponding data on weights and if this supports the data on numbers Government has agreed in principle to add this to HSG list.

Rollerball trials

Early results from the ground impact trial project showed a reduction of 17% in the volume of fish discarded when trawlers replaced traditional trawl gear with a roller ball system. The trials compared the standard hopper footrope with a system comprising rubber rollers, which allows the trawl to roll across the seabed rather than being dragged. You can read more about this here.

Conservation Credits Scheme

In Scottish waters a whole host of measure were introduced under the Conservation Credits Scheme including a "one-net rule" so that vessels carry only one regulated gear mesh size per trip. Special rules were introduced for twin-rig vessels and single trawl vessels. There have also been selectivity trials covering Nephrops, cod and whitefish mixed fisheries. You can read more about this here.

Project 50%

Funded by Defra and coordinated by Cefas, Project 50% used social scientists' skills to understand the reasons behind the apparent resistance to adopting new gear modifications and to help guide a new approach. Devon beam trawler crews agreed to try to reduce their discards by an ambitious 50%. Working with local net-makers, the fishermen trialled their own new net designs alongside standard trawling configurations. Average discards reductions of 52% were recorded, and the most successful boat achieving a 69% reduction. You can read more about this at Cefas.

Funding is allocated under the Scottish Industry Science Partnership and the Cefas Fisheries Science Partnership Project to undertake selectivity trials. More about this can be found here and here.

North Sea 'Eliminator' Type Gear Trials

To provide new information on comparative catch profiles of the 'eliminator' trawl to those from a conventional trawl fitted with belly cod-escape panels. This modification has been demonstrated to reduce the catches of cod by over 55% in a mixed North Sea demersal whitefish fishery.

South Wales Bass Square Mesh Panels

To reduce catches of undersized bass through the use of square mesh panels. A lower percentage of undersized bass were caught, the percentage of undersized bass was 11% of the total bass catch when using the experimental trawl and 30% when using the control trawl; the number of discards of other species caught per hour per haul was on average 14% lower when using the square-mesh section; in general, a lower number of fish of 30cm in length and below were caught.

Seafish projects

Discard projects led by Seafish over the past years include: