Reducing dark spots in fillets by incorporating krill in fish feed

Trials undertaken by BioMar and Nofima have found that adding krill to fish feed can reduce the incidence of dark melanin spots in fish fillets.
December 11, 2015

In a trial carried out at BioMar\'s test unit at Senja, phrases such as \"unbelievable results\" were used when the trial data were processed. It has become increasingly apparent that incorporating krill in the feed will enhance the quality of the fish at slaughter. In this trial, the test feed containing krill produced a 19 per cent reduction in dark melanin spots in fillets.

These findings are contained in a new Nofima report in which 200 fish were examined by Turid Mørkøre and her team at Nofima. The feeding trial was conducted at BioMar\'s trial license off Senja using salmon that were transferred to seawater in the spring of 2014. The test feed used in the trial was Qardio, which contains krill (QRILL produced by Aker BioMarine). Other trials have also shown that Qardio can reduce dark spots as well as enhancing fillet quality, reducing inflammation and boosting HSMI resistance.

\"Significant attention is currently being devoted to the occurrence of dark spots in salmon fillets, both by the industry and by specialist institutions,\" saix Gunnar Molland, BioMar\'s product manager for fish health. \"The melanin discolourations are assumed to be the product of a permanent inflammation process and we have also found repeated indications that feed components which modulate inflammation help to reduce the development of spots. In addition to the role played by specific vitamins and minerals we have also seen the effects of the fatty acid balance. As a consequence, it did not come as any great surprise to find that Qardio, which was already known to reduce the harmful effects of virus infections on the heart, has now also been shown to reduce the occurrence of dark spots in the fillet. The discovery that the same virus (PRV) that causes HSMI is found in dark spots in fish fillets suggests that the virus may also play a role in this context.\"

BioMar will apply the new knowledge generated in this work in the development of tools for the industry, and aims to launch a product designed to promote cost-effective prevention of fillet spots early next year. Operational stress appears to be a significant factor in the development of dark spots.