Greener bottom trawling
Norwegian trawlers are cutting their operating costs by flying doors high keeps nets off seabed while the trawls stay on the bottom.
It is said that this gear combination offers great possibilities for trawling by keeping the doors off the bottom. This system has been in development for some time and trials have been taking place on a number of trawlers in Europe and the US. It could also be one possible way of combating the growing green lobby that is seeking to ban bottom trawling around the world.
The main reason behind this is that the usual demersal trawl doors are replaced with a weight that keeps the bridle ends down, while a pair of pelagic trawl doors is towed ahead of the weight and clear of the ground to provide spread. This approach to bottom trawling relies entirely on hydrodynamic force to open the gear, eliminating the ground shearing force and seabed impact.
Experts informed that this method could be used to reduce demersal trawling costs, as well as cutting the ground contact of fishing gears, including shrimp trawls towed at slow speeds. It is told that in the bad weather these trawlers could work through and the switch to a single trawl from twin-rigging make a direct comparison between gears difficult. This system has 10 percent fuel saving by lifting the doors off the ground and down-sizing them.
Many fishermen now expects the cost of the fishing gear to fall with this system as the wear and tear on the trawl doors is eliminated and transferred to the chain weights instead. But there should be good long lasting doors as the doors donâ€™t last long, especially in Norwegian waters on very hard ground.
Source: Fishing News International
WorldFishingToday - 06-09-2010