pelagic
Pacific Herring
Clupea pallasii
Elongated, laterally compressed body with a single dorsal fin, a deeply forked caudal fin, and no adipose fin. The scales are large and easily shed. Coloration is typically dark metallic blue or greenish-blue dorsally, transitioning to silvery-white sides and belly.
- Habitat
- Inhabit marine and sometimes brackish waters of the Nort…
- Size & weight
- Typically ranges from 20 to 30 centimeters in length and…
- Diet
- Feeds primarily on zooplankton, including copepods, euph…
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Physical characteristics
Elongated, laterally compressed body with a single dorsal fin, a deeply forked caudal fin, and no adipose fin. The scales are large and easily shed. Coloration is typically dark metallic blue or greenish-blue dorsally, transitioning to silvery-white sides and belly.
Habitat & distribution
Inhabit marine and sometimes brackish waters of the North Pacific Ocean, ranging from shallow coastal bays, estuaries, and nearshore waters to the open pelagic zone.
Behavior
Forms massive, highly synchronized schools in the pelagic zone to reduce predation risk. Exhibits seasonal migrations between deep overwintering grounds and shallow spawning areas.
Diet
Feeds primarily on zooplankton, including copepods, euphausiids (krill), amphipods, and fish larvae, using filter-feeding mechanisms while swimming.
Reproduction
Broadcast spawners that migrate to shallow coastal waters in spring, where females deposit adhesive eggs onto submerged vegetation, rocks, or substrate, fertilized externally in the water column.
Ecological role
Serves as a crucial forage species and vital link in the marine food web, transferring energy from plankton to larger predatory fish, seabirds, and marine mammals.
Similar species
Other forage fish like sardines and anchovies, which can be distinguished by specific scale patterns, body proportions, and head shape.
Identification tips
Look for the lack of an adipose fin, a deeply forked tail, a single short dorsal fin near the midpoint of the back, and brilliant silvery flanks.
Interesting facts
Pacific herring spawning events can be so massive that the water turns milky white from the volume of milt released, attracting hordes of predators and covering the shoreline in roe.