The advent of a new lighting technology based on Cold Cathode Light Tubes enables fish farmers to improve the growth rate of farmed cod significantly. Scientists at The Icelandic food research company MATIS say that results after one production cycle indicates that using this technology can possibly delay or suppress the maturation of farmed cod. The research project is a two year EU-sponsored project called CODLIGHT-TECH.

Cod, held in intensive culture in sea pens, mature within 2 years from hatching, loses somatic growth rate, decreases condition, deteriorate flesh composition and loses at least 25% of wet weight. A delay or cessation of maturation during on-growing is therefore crucial for profitable farming. Seasonally-changing day length (photoperiod) is the natural time-keeping mechanism used by finfish from temperate latitudes to trigger a number of important physiological processes, including sexual maturation. Overlaying of artificial illumination on the natural day-night cycle in day length masks this seasonally changing signal and has been shown to successfully regulate maturation in a number of tank-based studies in Atlantic cod in which a complete cessation of maturation and up to a subsequent 60% improvement in growth have been observed.

Wild stocks are dwindling worldwide and the increasing rarity of wild cod, in conjunction with the continued high demand for the fish, has pushed up the price of cod and made cod farming financially viable. Some estimates predict that by 2010 the production of farmed cod may have reached 175.000 metric tons. However, overshadowing this is the experience of what happened to farmed salmon, an industry burdened by a seemingly endless stream of bad publicity in recent years. Environmentalists have complained about the chemicals used to treat fish diseases, the pollution from salmon farms that goes directly into the sea and the detrimental effect of fish farms on wild salmon populations.

Dr. Thorleifur Agustsson, project manager at MATIS and coordinator of the CODLIGHT-TECH project claims that there is little to worry about. He says that by suppressing maturation the threat of a possible genomic re-assortment is not at hand anymore. As far as pollution from the cod farms is concerned, dr. Agustsson points out that by increasing the growth rate there will be a better feed utilisation which will both make the farming more profitable and more environmentally friendly. Finally, increased cod farming will decrease the strain on wild cod stocks, says dr. Agustsson.

The CODLIGHT-TECH project is an EU-project involving parties from several European countries: MATIS - Food Research, Innovation & Safety and various fish farming companies in Iceland; The University of Stirling and Johnsons Sea Farms in Scotland; Institute of Marine Research (Havforskningsinstitutet) in Bergen, Fjord Marin and Intravision Group in Norway and; The Swedish University of Agricultural Sciences in Uppsala, Sweden.