Herring Spawning

One of the great spectacles in North American wildlife watching is the Pacific herring spawning. It happens every year in late winter and early spring. Not only does the event produce the next generation of an important fish species, it also sustains the current generation of many other animals.

Pacific herring form an important strand in the food web. They are classified as forage fish, meaning they serve as meals for larger fish like salmon. As we'll see a little later, herrings feed the larger community beyond just the salmon.

Herring spawning turns the sea white (Prince William Sound Conservation Center) 

Herring move to shallower seas during spring, which happens to be right around the same time hungry humpback whales arrive from the tropics. The herring are looking for eelgrass or kelp beds for their sticky eggs to attach to. After the females lay their eggs over the vegetation, the males swim over and release their milt to fertilize the eggs.

Before reaching the spawning beds, the herring must navigate a maze of predators: sea lions, sea birds like cormorants and gulls, bald eagles, and those hungry, hungry humpbacks. Once the work is done, the eggs aren't safe and the smorgasbord continues as diving ducks pick them off. About two weeks later, the remaining eggs hatch and the herring larvae are carried by the tide and are subject to predation by fish of all shapes and sizes.

Herring eggs attached to kelp (US Geologic Survey)

With all that eating going on, it's a wonder any herring survive to adulthood. Females typically lay 20,000 eggs a year, and if she lives a long life, she'll do this three times. Multiply her by a million of her closest friends, and you have about 20 billion eggs. If only 1% hatch, that's 200 million baby herring.

Sea lions await their feast (Tillamook Coast)

In a good year, spawning herring will color the sea white. However, the spawning isn't nearly as good as it used to be. Overfishing is one reason, but loss of habitat (spawning and feeding areas) and pollution are also big contributors.
This week's information comes from Wayne Hoffman, Ph.D. and Washington Department of Natural Resources.
nm1: Prince William Sound Conservation Center https://pwssc.org/herring-spawn/
nm2: USGS https://www.usgs.gov/media/images/pacific-herring-eggs-macrophytes
nm3: Wayne Hoffman https://tillamookcoast.com/blog/spawning-of-pacific-herring/