Alewife, are several other fishes that as a group are commonly referred to as river herring; alewife, blueback herring, American shad, hickory shad and other migratory shad on the east coast. Alewives spawn in freshwater but spend most of their life at sea. They don’t jump like salmon, but they can swim very fast in short bursts to pass through rapids. In spring, they migrate from the ocean back to their home rivers to spawn.