Egging on Sea Duck Recovery: Scientists testing new method for boosting waterbird populations in Richardson Bay

In an effort to find new ways to support the spectacular waterbirds of San Francisco Bay, ecologists with the U.S. Geological Survey (USGS) are working with the Richardson Bay Audubon Center & Sanctuary to test out a potentially new way to provide food for declining Surf Scoters, a large sea duck that was once much more common here.

“San Francisco Bay is a vital migratory stop for a wide variety of waterbirds, and anything we can do to support these birds is invaluable,” said Jordan Wellwood, director of the Audubon Center & Sanctuary. “We’re greatly pleased to partner with the USGS on this research that will ultimately benefit the work that we do for waterbirds.”

The study will take place in Richardson Bay between October and February of this winter, and neighbors will see research boats on the bay during what is typically the Sanctuary’s closure season. Any questions about the project can be directed to the Richardson Bay Audubon Center & Sanctuary at 415-388-2524.

The USGS researchers are actually looking to an age-old technique for harvesting herring roe as a way to provide food for Surf Scoters. For many years, fishermen have collected and dangled kelp fronds in Bay waters to attract spawning Pacific herring, which lay their sticky eggs on the kelp. Fishermen harvest the eggs and kelp together and sell them as “HEOK” (herring eggs on kelp) to caviar importers.

Since many seabirds also enjoy herring roe—it comprises as much as 50% of Surf Scoter diets while they winter in the Bay —USGS scientists will deploy temporary floating rafts of HEOK within Audubon’s waterbird sanctuary in Richardson Bay to see if improving food resources can ultimately help boost Surf Scoter numbers. Other rafts will be deployed to cultivate native mussels, which are also preferred prey for Scoters, and help grow natural reef habitat that supports several native species in local waters.

“The big question we’re hoping to answer is whether we can improve the circumstances for these birds by providing additional food resources,” said USGS ecologist Susan De La Cruz, who is leading the research. “Ultimately, we hope to develop new strategies for ensuring healthy sea duck populations in San Francisco Bay into the future.”

When the oil tanker Cosco Busan struck the Bay Bridge and spilled more than 50,000 gallons of heavy fuel oil into San Francisco Bay in 2007, hundreds of oiled birds sought refuge at the Richardson Bay Audubon Sanctuary in northern San Francisco Bay. Surf Scoters were the hardest-hit of these seabirds; Sanctuary staff and volunteers counted 166 oiled Surf Scoters out of a total of 414 oiled birds, just within the Richardson Bay. Throughout San Francisco Bay, many more birds were impacted by the spill.

At the same time, Surf Scoters have been declining at an alarming rate over the past few decades, and Dr. De La Cruz and others have been investigating the cause of their decline, seeking to provide scientific findings to guide restoration actions in San Francisco Bay and along the Pacific Flyway.

“We’re looking forward to seeing how the birds respond to the HEOK project. The findings from this winter’s study will help inform our conservation efforts for Surf Scoters and potentially other wintering waterbirds in the Bay,” says Wellwood.

(Surf Scoter photo by Andrew Reding)

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