72 Microseasons of the Pacific Northwest

Each spring, Pacific herring (Clupea pallasi) transform the shallow eelgrass beds of Puget Sound and the Salish Sea into a spectacle of aquatic renewal. Schools that have wintered in deeper water move en masse into the intertidal and shallow subtidal zone, where females deposit transparent adhesive eggs onto blades of eelgrass (Zostera marina) and marine algae. Spawning is so dense in productive years that the eggs coat the vegetation in a pale white film visible from shore. The Cherry Point herring stock in Whatcom County spawns from early April into early June — one of Puget Sound's most important remaining runs. The spawn triggers a feeding frenzy that reaches every level of the food web. Surf scoters, Barrow's goldeneyes, and bufflehead dive repeatedly over spawning schools, gorging on eggs and milt. Great blue herons stand at the tideline. Bald eagles congregate in nearby trees. Pacific harbor seals haul out nearby between feeding bouts. In very productive years a slick of milky-white milt may be visible on the water surface, and the scent of the spawn — faintly sweet and marine — carries to nearby beaches. For observers, the shorelines of Padilla Bay, Samish Bay, and the flats around Chuckanut Drive (Skagit and Whatcom counties) are productive viewing areas. On the Canadian side, the estuaries around Boundary Bay and Comox are notable spawn sites. The spectacle can be viewed from shore at low tide or from a kayak just offshore. The eelgrass beds themselves, once common throughout the sound, have declined significantly, making any intact spawn a welcome ecological marker of the season.