Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (North Atlantic): American shad. [Alosa sapidissima]

After a drastic decline in abundance, the American shad (Alosa sapidissima) is being restored in many of the rivers along the East Coast that originally supported large runs. The American shad is an anadromous fish that lives several years in the ocean and returns to its natal river to spawn in the spring when temperatures reach 12/sup 0/C. The eggs are carried by currents downstream from spawning sites in large rivers for 8 to 12 days until they hatch. The larvae, which metamorphose to the juvenile stage in 3 to 4 weeks, remain in the river until fall when they migrate to the sea. Shad move offshore and southward during winter at water temperatures of 3 to 15/sup 0/C. American shad feed on zooplankton. They adapt readily to fresh- or saltwater, but they prefer salinities exceeding 4 ppt.