1. To assess the performance of a standard Nephrops trawl incorporating a Scotnet Internal Cod Flap (SICF) in reducing by-catches of cod. Catches from the modified test trawl will be compared to those retained by unmodified control trawl rigged with a 110 mm square mesh panel (SMP).
2. If time allows under water observations will be made of the SICF using a self-recording mini TV system.
Staff and equipment will join MV Virtuous (FR253) at Fraserburgh on 17 January. Prior to sailing one of the vessels standard Nephrops trawls will be modified to include the SICF, which incorporates a 200 mm (full mesh) square mesh netting panel. The internal panel is inserted into the trawl where there are 200 meshes in circumference and is rigged with a slight incline. The top half is attached under the top sheet netting between selvedges length for length. The lower half is left unattached to the lower sheet netting and incorporates a leadline laced around the lower panel edge, weighing 2 kg per m. A fish outlet hole is cut out of the top sheet netting directly ahead of the internal panel reducing from 50 meshes to 30 meshes on a bar cut.
Throughout the trials, the twin trawl method will be used to assess the performance of the test net which will be compared against a similar unmodified control trawl. Catch comparison data will be collected using 80 mm diamond mesh codends. The test trawl will be rigged with a 120 mm SMP and the control trawl a 110 mm SMP as per 2009 regulation. The intention is to collect length data for all cod, haddock, whiting, anglerfish and weight data for Nephrops but as available other species may be included.
On leaving port, the vessel will sail to suitable Nephrops fishing grounds in the North Sea. Thereafter the vessel will commence catch comparison hauls for the remainder of the survey. If time allows a number of short observation hauls (approximately one hour) will be made on the SICF using a self-recording mini TV system.
Ships accommodation will be used throughout and the charter will end in Fraserburgh on 25 January.
Robert J Kynoch (Marine Scotland Aberdeen Marine Laboratory)