Winter catches are made between 40 and 43 degrees north latitude and spring catches over the entire continental shelf area. For both species, growth rates, age at sexual maturity, and longevity vary greatly according to geographic location. Throughout their ranges, alewife tend to be longer than blueback herring of the same age. Within each species, females tend to grow somewhat faster than males. Age at sexual maturity for both species is primarily ages 3-5 in the northern portion of their ranges.
Fecundity increases with size and age.
River herring suffer relatively high rates of mortality throughout their life cycles.