New sorting system for blue whiting
Vónin in the Faroe Islands has introduced a new sorting system for blue whiting, made up of a four-sided net tunnel with a flexible grid fitted inside.
It says this separates out larger fish from the blue whiting. The large fish do not pass though the grid but swim out through a bottom opening. The tunnel is made of nylon netting with the lacelines made of Euroflex, the same material used in the lacelines of the belly.
The tunnel tapers towards where the grid is mounted and then widens at the same rate towards the bag to maintain a good flow through it.
The sorting section is attached between the belly and the bag.
The sorting grid is built up of multiple short tubes, held together by strong Dyneema twine. The distance between each tube is less than 55mm, and since the twine does not stretch at all, the grid maintains its original size.
Durable
The grid is manufactured to match the shape of the tunnel and is attached to the sides. Vónin says the tubes have a superb flow and are fully stretched while towing.
As the sorting section is being towed through the water, it acquires an oval shape. It is mounted at an angle of 45-55. Underneath the grid, a chafing mat is attached under the opening where the large fish escape.
Vónin says that "the greatest advantages with this grid, compared with the usual steel and plastic grid, is that you don't need to show any special care while taking the gear on board, as the sorting section is reeled onto the net drum, with the rest of the trawl, without suffering any damage."
Vónin says this type of grid is widely used in the fish farming industry and it is the first time it has been put to work on blue whiting trawlers.
The sorting section has already been trialled on board pelagic vessels and complies with all demands set for blue whiting fisheries, a statement from Vónin added.
