Migration data

Pacific herring can be found in inshore and offshore waters of:

• the North Pacific
• the eastern Pacific from Baja California to the Beaufort Sea in Alaska

Pacific herring mature and spawn between 3 and 5 years old, though some spawn as young as 2. Adult herring migrate from the open ocean to sheltered bays in late fall every year to spawn. Both spawning age and migration date depend on latitude and other factors, with herring at higher latitudes generally spawning later in the year and at an older age. Conditions that trigger spawning are not altogether clear.

Herring begin their spawning cycle by congregating in deep channels. After several weeks, both males and females enter shallower intertidal or sub-tidal waters such as sheltered bays and estuaries. Herring prefer to spawn on eelgrass or other submerged vegetation and rocks, and a single female may produce as many as 20,000 eggs in 1 season.