Alosa "oligorakered." The multirakered are primarily plankton feeders, the oligorakered have large rakers and are predators, and the medium-rakered generally consume a mixed diet. Most current species of the genus "Alosa" in North America can be found in Florida, whereas the distribution of most of them is broader. Morphology is notoriously liable to adapt to changing food availability in these fish. Several taxa seem to have evolved quite recently, making molecular analyses difficult. In addition, hybridization may be a factor in shad phylogeny. Nonetheless, some trends are emerging. The North American species except the American shad "A. sapidissima" can probably be
Alosa sources, predators, etc. Since many adult "Alosa" species die after spawning, the young generally have to migrate to the sea from the spawning grounds. Duration of migration varies among fish, but it can greatly affect survival. Reproduction varies by species. Studies done on "Alosa" in Iranian waters have shown that spawning varies in time, place, and temperature of the waters they inhabit. Fecundity may also vary. Species are known to spawn as early as April or as late as August. Temperatures range from about 11 to 27 °C. Fecundity can range from 20,000 to 312,000 eggs. Eggs are pelagic. The