A marine mammal caught in a trawl never fails to be a nightmare. Gear designers at Killybegs fishing gear company Swan Net Gundry have a simple innovation to avoid this situation – saving both the fisherman and the mammals much grief.
Observations of trawls have shown that seals can often sit on the head or belly sheet of a pelagic or bottom trawl with pectoral fins hooked just over the head rope – almost as if just hitching a ride.
A seal can stay there for some time observing the fish entering the trawl and occasionally entering the trawl itself to feed. Known for their playful behaviour, recorded data shows the ease with which they like to use the trawl by bouncing on the netting sheets from the outside – using it as a trampoline.
Swimming in the direction of the tow, inside the trawl a groups of seals often gather at a point where the bellies reach a diameter of two to three metres and they swim with the trawl and feed on the fish that are concentrated in the area.
In this scenario the damage that the seals do to the volume of the catch is negligible but, as can often happen, if the seals enter the codend where space is much more limited, then problems can develop, resulting in them potentially getting caught along with the catch.
However, a solution, designed by SwanNet Gundry (SNG) to keep seals from entering the codend has been working extremely well for skippers who have trialled the new Excluder Device.
One skipper comment that having lost no fishing time with entangled mammals in the trawl, as was previously happening, the performance of the Excluder ‘sealed the deal’ for him.
Feedback from the successful performance of this device has led to SNG designing a range of other excluder models to exclude a range of marine mammals and larger groundfish from trawl gear.