Greener bottom trawling
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| Norwegian trawlers are cutting their
operating costs by flying doors high keeps nets off seabed
while the trawls stay on the bottom. |
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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.
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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 don’t
last long, especially in Norwegian waters on very hard ground. |
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Source: Fishing News International
Photo: Thyboron Trawldoor
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WorldFishingToday 11. March 2009 |
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