For example light, is of crucial importance to larval fish. They rely on light to find food. For the two ecosystems that we are interested in here, there is a strong seasonal variation of number of light hours per day available to feeding in the Barents Sea. The number of light hours changes from 12=24 hours per day. For the Georges Bank, the seasonal variation in number of lighthours are much more constant. These properties make it distinctly different two grow up in the Barents Sea or the Georges Bank.