SIZE :
Generally less than 30 cm.
LIFE EXPECTANCY :
Up to 10 years.
LIFE CYCLE :
Sexual maturity around 4 or 5 years.
Alewives are born in lakes or the calm stretches of rivers in late spring. Juvenile fish remain in freshwater until the autumn, during which they swim to the ocean or deeper waters. Adults will return to freshwater in the spring to spawn, and then head back out to sea.