First big herring run in San Francisco Bay creates feeding (and birding) frenzy

This past week marked the first big Pacific herring run of the year in San Francisco Bay. Herring is serious business for many of the birds we love, providing a rich, nourishing winter smorgasbord for hungry waterbirds on the Pacific Flyway. With climate change causing big changes in the availability of prey for waterbirds and seabirds, it’s more important than ever to protect this vital food resource. (photo above by Kerry Wilcox)

Pacific herring is an incredibly essential prey item for dozens of birds and a vast array of other marine wildlife and predatory fish such as salmon. Birds aggregate in Alaska, the Salish Sea, Puget Sound, Yaquina Bay, Humboldt Bay, Tomales Bay and San Francisco Bay to eat spawning fish and feast on the roe. In California, sea ducks and dabbling ducks such as surf and white-winged scotor, scaup, and harlequin ducks, and gulls such as Heermann’s, mew and western gulls eat the eggs. Waterbirds such as brown pelican, western and Clark’s grebe, and Brandt’s cormorants eat the spawning fish.

Dan Singer, local expert naturalist affiliated with e-bird and with Western Field Ornithologists, observing birds on Richardson Bay.

Herring spawning sites are special and unique – far less than 2% of the total coast is utilized by herring- and therefore must be protected. Current impacts on Pacific herring include traditional problems such as shoreline hardening and modification, direct damage to eelgrass beds and other spawning sites, pollution, sedimentation, overfishing (at some sites in Alaska and British Columbia). Now, there are the new problems of climate change and ocean acidification. Preliminary analyses currently being prepared for publication by Audubon California and our partner, the Farallon Institute for Advanced Ecological Research, show a long-term declining trend in herring spawning biomass in most regions from British Columbia through Alaska.

Relative sizes of herring spawning biomass showing the importance of San Francisco Bay. Analysis and map by Audubon California.

Fortunately, however, herring are responsive to precautionary management that includes low rates of commercial harvest; protection  of eelgrass and macroalgae beds; avoiding dredging during spawning season;  and water management regimes that provide appropriate salinity ranges for spawning.

San Francisco Bay is the most important spawning site for herring south of British Columbia - this food resource supports nearly a dozen Important Bird Areas here and in Tomales Bay just to the north. Greater Richardson Bay which includes the Richardson Bay Audubon Center is the epicenter of herring spawning on the west coast. It is hard to believe that 50 years ago, this entire shallow bay was very nearly filled and paved. It was saved thanks to dedicated activists.

Due to the hemispheric importance of Pacific herring as a food resource, Audubon California is leading a campaign to protect herring in California. Together with California staff of our NGO partner Oceana, over the past two years we created an unprecedented alliance with commercial fishing fleet leaders and state fisheries managers. The result is a forthcoming “fishery management plan” that will serve as the home for new, specific regulations and stewardship practices to protect herring in California in perpetuity.

Meanwhile, in greater Richardson Bay, one of the west coast’s hottest spots for waterbirds and herring, right now tens of thousands of waterbirds have gathered to feed and digest in peace in the closed waters of Audubon’s Richardson Bay Center. Grebes, cormorants and pelicans are diving for fish; gulls grapple for scraps; and waterbirds dabble and sit quietly. The resulting wildlife spectacle in one of the most urbanized estuaries in the world is an inspiration for us all.

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