Not only affecting the light on the cod's puberty. The light also affects muscle development and how large the adult cod. The search for growth genes that give the best result, is well underway.
While mammals have as many muscle fibers from birth until we die, change the number of muscle fibers in cod significantly during their lifetime. The number of muscle fibers enter the fish's potential to grow big.
Research shows that the light of cod fry exposed to, have an impact on the fish's growth into adulthood.
Associate Professor of Biology at the University of Nordland, Jorge Fernandes, has since 2009 conducted research on how light and maturation affects muscle development in cod.
- With continuous light increases growth significantly in cod. We can actually see the effects of phototherapy on both gene expression and levels of sleep hormone melatonin already after 12 hours, says Fernandes.
Plus 10 percent in six months
Through half a year, test fry continuous light, while the control cod was the amount of daylight is normal in Bodo, where the experiment was conducted.
This means that the control cod was light 24 hours a day during the period of midnight sun, but similar low light in winter. The fry weighing about 2 ounces when the experiment started.
The tests show a significant improvement in the growth of juveniles who received continuous light. The analysis of muscle tissue revealed that more light, thinner, but more muscle fibers than the smaller amount of light.
- Thus lysbehandlet fish potential to grow larger than untreated fish, says Fernandes.
An increase in the number of muscle fibers in farmed cod is very interesting in a commercial context.
- Other research has shown that the effect of continuous light in juvenile cod are also evident three years after the light treatment, where it is larger than the fish that have not received the same amount of light that is small. No one knows with certainty what the molecular mechanisms underlying this phenomenon is due, says Fernandes.
Will delay sexual maturation
Farmed cod fast growth allows it to become sexually mature earlier than wild cod. In the wild, taking the cod three to four years to reach sexual maturity. Farmed cod are sexually mature after about two years, while it only weighs around 1.5 kg.
Maturation, the cod will focus your energy on developing eggs and milk, rather than grow. This constitutes a serious problem for the cod farming industry.
- We want to understand the negative effects that sexual maturity has to grow, and looks specifically at how muscle development is changing the cod's puberty, says Fernandes.
In the commercial context, it is desirable to postpone farming cod maturation. Also this process can be manipulated by light.
In order to understand how light affects the maturation and growth in cod, mapping Jorge Fernandes and his colleagues now also cod's biological clock.
- We are trying, among other things, to map how genes cod growth and properties affected by maturation and lysendringer. The hope is to identify the genes that give the best results for growth related to light and sexual maturity, says Fernandes.
