The herring spawn is one of the most spectacular natural events that occurs annually on the west coast of North America. Each year, tens of thousands of herring migrate from the open ocean to coastal areas were they spawn in remarkably large numbers. The males release ‘milt,’ which contains sperm, and the females release eggs into the surrounding intertidal beds of eelgrass and kelp. This spawning event usually colours the water white and draws an enormous number of predators and scavengers, including whales, sea lions, seals, and sea birds, that take advantage of the feeding frenzy to come inshore and forage, often for weeks at a time.

Herring are a crucial component of the marine food web, and are an important prey species for many marine mammals in the Pacific Northwest including fin whales, humpback whales, sei whales, long and short-beaked common dolphins, pacific white-sided dolphins, harbour porpoise, Dall’s porpoise, Northern fur seals, Steller sea lions, California sea lions, and harbour seals. Pacific herring are also an important species for First Nations communities, and are valued for their trade, food security, and cultural traditions. Pacific herring have been heavily exploited as a result of overfishing, with Pacific stocks peaking in the early 1960s and collapsing shortly after that in 1967.

Researchers at the Hakai Institute’s Calvert Island Field Station have been studying the herring spawn phenomenon to determine where and why the herring spawn and to determine the potential implications for the highly debated fisheries management plans. Their team is currently in the field; watch the video below to learn more about their on-going herring spawn research projects.