Most produce small planktonic eggs about 1mm in diameter. Generally, the eggs are slightly positively buoyant and mixed through the water column, transported by tides and currents. Other species, like the winter flounder, produce demersal eggs that are attached to the bottom substrate. Larvae hatch from the eggs within a period of days to weeks depending upon the species and temperature. After a few weeks to several months of rapid growth, the larvae metamorphose to the juvenile stage when they first begin to resemble the adults.
Mortality is very high during the first months of life.
It is a rare individual that survives to reproduce or to be caught in a targeted fishery. Many species of marine fishes, including the cod, haddock, and yellowtail flounder found off the northeast United States, are heavily fished and abundance levels are low. Reduced catches and restrictions on the fishery have led to increased interest in the factors that control fish production and in methods for mass cultivation. The environment is thought to play an important role in determining growth and survival during the early life stages of fish, but the linkages and mechanisms have been difficult to establish. Factors such as temperature, storms, fronts, and eddies are considered critical to feeding and retention of planktonic larvae in areas favoring rapid growth and survival.