Most Canadians don't know that hundreds of millions of tonnes of herring are now converging to spawn along the shores of Canada's Pacific coast. Scott Wallace, Sustainable Fisheries Analyst at the David Suzuki Foundation, thinks the annual herring spawn is the most ecologically significant event of the year on the Pacific coast. He compares it to the great migrations in Africa, but says that because this migration is underwater, few of us notice. It's actually easy to see. Herring spawn along the shoreline, and the abundance of fish and milt—or sperm—can turn the water white. Stretches of milky water full of milt, fish and eggs can stretch for kilometres. The spawning activity can be seen from the air: fisheries biologists determine herring populations through aerial surveys, measuring the length of coastline that has turned white.
You won't see just herring. As they arrive, the predators swoop in, and there's plenty to go around. Sea lions, seals and birds such as surf scoters, Brant geese and seagulls are part of nature's display during this event. Even little creatures like hermit crabs, surfperches and smelts take advantage of the rich nutrients provided by the deposited herring eggs. The Brant goose's migration from the Baja is timed perfectly to meet the herring spawn, which provides them with a rich food source to fuel their journey onward to the Arctic. It's such an event that the City of Parksville celebrates the convergence of wildlife with its annual Brant Festival. Of course, people come in to catch the fish, but it's the herring's roe that has the most commercial appeal, mostly for the Japanese sushi market.
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The herring lay their eggs on just about anything along shoreline, mostly kelp and eelgrass. But they can be found laying eggs on dock pilings, rocks and other seaweeds. First Nations people used to put hemlock branches into the water when herring spawned, and would then pull the branches from the water when they were teeming with herring eggs. A strange sounding (but delicious—I've tried it) product of herring spawning is roe on kelp. Kelp is a type of large, brown leafy algae that can grow up to 50 centimetres in a day, and makes an ideal nursery for herring. Nature is the sous chef, putting these ingredients together, so you just have to you pop the chewy, nutritious and delicious treat into your mouth. It was an important part of the diet of First Nations, and has become popular in Japan. British Columbia provides about 80 per cent of the world's roe-on-kelp supply.
Don't miss the ecological event of the year. Keep your eye out for milky water, or make your way up to Parksville for the Brant Festival to see this incredible annual cycle.
Do you have a story about the ecology of Canada's Pacific Ocean that you would like to share? Write to us at firstname.lastname@example.org