Pacific Herring

The Pacific Herring is a small, silvery schooling fish in the family Clupeidae, the North Pacific counterpart to the Atlantic Herring. It ranges widely across cold coastal waters from California north through Alaska, across the Bering Sea, and along the coasts of Russia, Japan, and Korea. This species forms massive schools and is one of the most important forage fish in North Pacific marine ecosystems, providing a critical food source for salmon, seabirds, whales, and other predators. Its annual spring spawning events, during which nearshore waters turn milky from released eggs and milt, are a well-documented and ecologically significant seasonal phenomenon along many stretches of the Pacific coast.

Field marks:

• Slender, laterally compressed body, silvery on the sides and belly
• Dark bluish-green back with an iridescent sheen
• Single short-based dorsal fin near the midpoint of the body
• Deeply forked tail fin
• Loosely attached, easily shed scales
• No lateral line visible along the body
• Adults typically 18-30 cm

Pacific Herring are nearly identical in appearance to Atlantic Herring but are geographically separated, occurring only in the North Pacific rather than the Atlantic. They can be distinguished from Pacific Sardine by the absence of dark spots along the flank and from anchovies by a shorter, non-protruding snout and terminal mouth.

Pacific Herring inhabit cold, temperate coastal and shelf waters throughout the North Pacific, ranging from central California northward along the west coast of North America, through the Gulf of Alaska and Bering Sea, and across to the coasts of Russia, Japan, and Korea. They are a pelagic schooling species typically found from the surface down to around 200 meters, moving inshore in spring to spawn on eelgrass, kelp, and other nearshore vegetation, then returning to deeper offshore waters to feed and overwinter. Estuaries and protected bays serve as important nursery habitat for juveniles.

Pacific Herring form large, highly synchronized schools that move together for feeding and predator avoidance, undertaking seasonal migrations between offshore feeding grounds and nearshore spawning sites. They feed on zooplankton by filtering prey from the water column with fine gill rakers. Each spring, adults migrate into shallow coastal waters in massive numbers to spawn, depositing adhesive eggs directly onto eelgrass, kelp, and other submerged vegetation in a spectacle that turns nearshore water milky white with milt. This mass spawning event attracts large aggregations of predators, including salmon, seabirds, sea lions, and whales, making herring a foundational species supporting broader North Pacific marine food webs.