Both herring and salmon, along with shad and smelt, are anadromous: They are born in fresh water, migrate to the sea to grow and mature, and later return to their natal streams and ponds to spawn. Unlike salmon, herring make the round trip more than once.
The two species of river herring, Alosa pseudoharengus and alosa aestivalis, are known by a host of local names - buckies, cat thrashers, kayaks, Gaspereaus, and alewives - to mention a few. From April through early July, when water temperatures rise, the herring begin to form schools close to shore.
"When the shadbush blooms, the herring run," is a Cape Cod maxim that holds true, suggesting that the fish, like the tree, respond to changes in light as much as changes in temperature.
The first summer of the young herring's life is spent in the safety of the hatching pond. By autumn, the young 2- to 4-inch fry migrate downstream to the sea to rendezvous in large schools along the coast.
Enter the hungry bass and blues, which lurk around the mouths of streams and tidal rivers. If the herring survive a three-year adolescence at sea, they will return to the birth pond annually for up to three years to breed.