Freezing methodThe first generation stern trawlers, built in the 1960s, did not have plate freezers on board. These trawlers were mainly targeting herring at that time and made relatively short trips. In 1968 a new herring regulation prescribed that herring had to be landed 'heavily salted' or 'deep-frozen'. The result of this regulation was that the vessels were 'forced' to install freezing equipment.

Also the ban on herring fishing in the North Sea (1977-1983) forced the trawler owners to a reorientation of their activities. It became necessary for them to fish in more distant waters on the Atlantic Ocean for other sorts of pelagic fish (such as horse mackerel). The freezing of fish on board - to maintain the freshness and quality - made that possible. The introduction of such equipment has had great influence on the operational management, the fishing methods and the size of the vessels.

Immediately after the catch, the whole round fish is chilled, deep-frozen (minus 23C), packed and stored in the freezer holds of the vessel. The whole process is carried out under strict conditions of hygiene as controlled by the different National Health Control Authorities. After 3 to 6 weeks at sea, the vessels return to the port, where the cargo is transferred to reefer vessels or to the cold storage facilities a shore.