Each individual faces enormous odds against it's survival, so each female cod lays millions of eggs. While fishermen are concerned about the movements and abundance of adult fish, many scientists focus their attention on the younger ones.
Millions die at each stage of maturity.
As long as two grow up to replace each two caught by fishermen, the race goes on. Cod spawn on the offshore banks in late winter and spring. Gradually, the eggs float to the surface layer. When they hatch, the tiny larvae live for a week or two on the contents of their yolk sacs. When this is used up, they feed on plankton for several months, then start settling to the bottom.