Construction of a new live-storage tank for fish and practical testing (Optipro 3). Final report

Summary

The majority of trawlers still drop their 20–30 ton catches directly into the receiving bin, similar to what was done 60 years ago. In 2015, FHF financed a project (number 901094) aimed at designing the future trawler. However, implementing new technologies on vessels is often connected with financial and technical risks. Thus, the FHF financed this project to test out a new prototype of a live-storage in a fish tank (4,5 m3). A tank with the capacity to hold 2000 kilos live fish. The tests show that the dispersion of water in the tank was optimal and gave a good result regarding survival of the catch (approximately 90 percent). In addition, the fish was able to restore itself during the live-storage. A swan-neck-shaped rigid tube did the draining of this tank and this worked very well, but required that the water level in the tank had to be emptied all the way down to the baseplate. Live-storage of fish for six hours contributed to a whiter colour in the fish muscle, as compared to traditional trawl quality. The same technology may also be used in the receiving bin of a trawler. Most of the fish may thus be kept alive until stunning and bleeding onboard trawlers, but it is necessary to take into consideration that fish increase the quantity of muscle blood during the first 2–3 hours of live-storage. Therefore, this may not contribute to a substantial improvement of the fish muscle quality, compared customary trawl quality.