The Underwater Tagging Equipment gives the following advantages:
·It prevents the need for hauling the fish to the surface for tagging and release.
·It makes it possible to tag deepwater species, which do not survive being surfaced.
·Less time is spent in handling the fish, which leads to increasing tagging efficiency.
·Fish is tagged in its natural environment, avoiding stress factors as pressure and temperature changes and therefore decreases tagging mortality.
The UTE is developed in co-operation with the Marine Institute of Iceland, Grandi (a large fishery company in Iceland) and the Research Council of Iceland.
The tagging process:
As a fish is inside the trawl and approaches the equipment at the cod-end of the trawl, it is enclosed by a grid which diverts the fish into tagging place.The fish is viewed through the onboard video camera, and the tagging gun is moved into position.
A knife makes a small incision into the skin of the fish for the DST tag to be pressed into its body cavity.Although the tag is inside the fish a small hose hangs outside to allow its identification.
After tagging the fish it is released through a channel in the device and out into open water.Each fish can be tagged in just a few seconds, much quicker than existing methods.
The operation is controlled by
the scientist sitting at a computer onboard the vessel.He
or she is able to see the fish on-line through the installed camera and
operate the device via a cable wire.The
only requirement for the vessel is that it is equipped with a standard
trawl, and a cable wire.
1) Fish is diverted into the UTE. The grid at the front end excludes larger fish.
2) Redfish locked in tagging position and ready for tagging. Tagging is controlled and viewed through the underwater camera.
3) Fish is released into the open ocean after tagging.