EUROPEAN CETACEAN BYCATCH CAMPAIGN
"Man is but a strand in the complex web of life"
"Man is but a strand in the complex web of life"
Demersal Pair Seine
(Courtesy of Scottish Executive)
(Courtesy of Scottish Executive)
2.5 This method of fishing was originally developed by single-boat flydraggers teaming up to tow a single seine net between them using up to 13 coil (2860m) of seine net rope (see above) in place of the wire warps and heavy sweeps of the pair trawl gear.
These vessels towed up to 0.5 nautical miles apart and increased considerably the area of sea bed swept by the gear. However this technique requires large areas of clear ground to function efficiently with the risk of snagging on rough bottom or underwater obstructions ever present so a hybrid method, a cross between pair seining and pair trawling, evolved.
By introducing 3-4 coil (660-880m) of seine rope between the heavy sweep and bridles of the pair trawl rig the area swept by the gear was considerably increased without the need to deploy long lengths of rope warps (Figure 6).
Distance between vessels was reduced to around 0.28 nautical miles and towing speeds range between 2.2 to 3.5 knots, the normal rate being towards the lower end of this range (2.5 knots). Like the pair trawl this gear is generally used in water depths under 200m and targets white fish species only.
Typical (and maximum) values for above components:- Trawl warp (a) wire diameter 19mm (22mm); Heavy sweep (b) wire diameter 22mm (26mm); Seine ropes (c) combination diameter 32mm (40mm); Bridles (d) combination diameter 16mm (24mm).
2.6 Due to the nature of demersal trawling, twin rig demersal trawling, demersal seine net and demersal pair trawl, and the restrictions they can put on vessel manoeuvrability, it is not always possible for fishing vessels to respond positively to requests to move out of the way of other vessels which are similarly hampered in their ability to manoeuvre eg seismic vessels. To overcome the problems associated with restricted fishing vessel speed and manoeuvrability it is recommended that early communication be established if access is sought across an area being fished.
These vessels towed up to 0.5 nautical miles apart and increased considerably the area of sea bed swept by the gear. However this technique requires large areas of clear ground to function efficiently with the risk of snagging on rough bottom or underwater obstructions ever present so a hybrid method, a cross between pair seining and pair trawling, evolved.
By introducing 3-
Distance between vessels was reduced to around 0.28 nautical miles and towing speeds range between 2.2 to 3.5 knots, the normal rate being towards the lower end of this range (2.5 knots). Like the pair trawl this gear is generally used in water depths under 200m and targets white fish species only.
Typical (and maximum) values for above components:-
2.6 Due to the nature of demersal trawling, twin rig demersal trawling, demersal seine net and demersal pair trawl, and the restrictions they can put on vessel manoeuvrability, it is not always possible for fishing vessels to respond positively to requests to move out of the way of other vessels which are similarly hampered in their ability to manoeuvre eg seismic vessels. To overcome the problems associated with restricted fishing vessel speed and manoeuvrability it is recommended that early communication be established if access is sought across an area being fished.
