using cylindrical grids in the codend

to reduce flatfish discards in the Dutch Nephrops fishery

Target species:
marketable Nephrops, plaice, turbot and brill

Area, Vessel
Catch comparison trials were carried out with a multi-rig (6) Nephrops trawl in the North Sea (ICES area IVc) on board the Grietje WR189 (23m, 300Hp).
Gear type:
demeral (multi-rig)

Gear modification
A tube made from three cylindrical grids and with an escape hole at the end was fitted inside a conventional 80 mm codend. The codline is tied around the escape hole which is at the base of the third grid. The idea is that undersized plaice, dab and Nephrops will enter the tube through the cylinrical grids and swim out the escape hole. Floats are attached to neutralize weight of the grid. The catches of this gear were compared with those of the conventional 80 mm codend gear.


Results:
After initial testing on a commercial vessel the captain reported that the grid did work but did not reduce flatfish discards by 50%.
Further information:
pieke.molenaar@wur.nl IMARES rapport C027/16 (http://library.wur.nl/WebQuery/wurpubs/498943)




Citation :
Molenaar, P. , 2017. using cylindrical grids in the codend . In O’Neill, F.G. and Mutch, K. (Eds): Selectivity in Trawl Fishing Gears. Scottish Marine and Freshwater Science Vol 8 No 1.