Population Many differences have been found between herring populations at different latitudes such as timing of spawning, age at maturity, and size. Identification of individual stocks has not been clearly defined. There may be numerous stocks in the eastern Pacific range with one in Oregon. In California, each spawning area is managed as a separate stock. It is likely stocks intermingle extensively on the summer offshore feeding grounds which would make single stock management difficult.
Researchers are unsure at which life stage year-class strength is established.
Other studies are showing relations with on-shore transport, water temperatures, and predation by pollock. There is general agreement, herring undergo substantial variations in natural abundance and may be more sensitive to fishing mortality and environmental change than species with more stable populations. Harvest Pacific herring have been utilized for centuries as a fresh or salted food source and for bait in other fisheries. In the mid 50's, use as a food source began to decline until it was only a minor fishery. In Oregon, the major fishery is a seine fishery in the Yaquina Bay for roe.