Pair Pelagic trawling is almost identical to single trawling except that when towed by a pair team, there is no requirement to use pelagic trawl doors. The spread of the net is determined by the distance between the boats and gear depth is controlled by changing the length of towing wires and/or altering towing speed.
One boat shoots the net and the partner vessel comes alongside to pick up the bridles. When both warps are shackled up, appropriate lengths of wire are paid out and the vessels steam towards the target shoals.
As with bottom pair trawls, the absence of trawl doors allows two vessels of modest horsepower to tow a relatively large trawl-net.
|Potential Impacts (Biological/Environmental)||Gear Selectivity||Regulation|
• Capture of non target fish species (minimal as single species fishery)
• Incidental bycatch of cetaceans
• Capture/discarding of undersized target species
• Minimal - no interaction with seabed
• Mesh size
• Wing/net body design
• Height in water column
• Net size
• Minimum mesh size
• Minimum fish sizes
• % of catch mix retained on board
Improvement measures and initiatives taken by Scottish Fishermen
• Through 2005/6 Areas IV & VI had 400 pelagic trawl fishing operations monitored by the SMRU to record cetacean bycatch. None was observed on any of these trips.
• Scottish Industry/Science partnership is currently working to investigate technical measures which can be employed in Scottish pelagic trawls to reduce the capture of juvenile mackerel.
• Moves by industry to convert mackerel trawls to Dynema fibre (an extremely lightweight, strong, non-stretch, polyethylene) has reduced twine diameter, overall gear weight, and sweep and warp replacement. This has resulted in significant reductions to drag and savings on fuel consumption, thus reducing carbon footprint.
• Mackerel trawls are now incorporating hexagonal mesh sections of net in the wings and around the net mouth, which are reducing net drag and fuel usage.