The fish should be bled as rapidly as possible and preferably immediately after capture, but this is difficult for trawlers and Danish seine vessels. The results from a series of projects point to the fact that more than 90 per cent of these catches may be kept alive in tanks on board the vessels.
Keeping the fish alive on board the vessel for several hours leads to dramatic quality improvements including, in particular, better bleeding and whiter fillet. However, after a longer period in live fish tanks, e.g. overnight, the fish has recuperated and is then extremely difficult to kill and bleed. It is necessary to kill and bleed the fish automatically in order to exploit the quality potential.
Machine kills and bleeds in one operation
Nofima has, through a project financed by the Norwegian Seafood Research Fund (FHF), tested slaughtering technology for salmon on board large coastal fishing vessels. The stunning and bleeding technology of Australian company Seafood Innovations is now being tested through the use of the machine SI-7 Combo, which kills and bleeds the fish in one operation.
Three trials have been carried out on different vessels. In the first trial, the efficiency of the machine was measured on board M/K Kildin from Btsfjord. The machines were placed directly on the receiving bin, which provided produced poor working conditions. However, in spite of this, more than 30 cod were bled per machine per minute. This equates to 10-12 tonnes of slaughtered and bled cod per hour.
The machines ability to kill the cod was also documented through studying the bleeding in the cods brain. The scientists ascertained that the cod died immediately. However, the Australian machines are constructed for slaughtering salmon and, as a result, it was difficult to achieve good and even bleeding of cod.
Adjustments gave good results
Prior to the trial on board M/K Bernt Oskar in 2012 adjustments were made to the blade and a new entrance to the machine was developed based on the shape of the cods head.
Earlier trials have shown that the single cut method produces bleeding that is equally as good as traditional methods, such as cutting the throat or all the gill latches on one side.
In the last trial we observed that the machine struck accurately on large and small cod alike, says Senior Scientist and Project Manager Kjell . Midling.
Consequently, this machine will be able to be utilised in catch handling on board the trawler and Danish seine fleets and make the catch handling more efficient and safer, concludes Midling, who is planning new bleeding trials during the autumn and winter.