They're Back!

Native Oysters Return to the Bay

By Juliana Gonzalez

The San Francisco Bay was once brimming with oysters. Enough in fact to support the largest oyster industry on the West Coast. Yet, by the early 1900's, California's population and industrial growth led to a degradation of water quality in the Bay and by 1939, the last of the native oysters in San Francisco Bay were commercially harvested. Today, The Watershed Project is excited to help lead an effort to restore native oysters to the San Francisco Bay. Our "Oysters on the Half Shell" Program involves three interconnected approaches: restoration, monitoring, and education.

Restoration of the native oyster population in the Bay is currently led by the Native Oyster Working Group, with pilot restoration sites along Marin, Contra Costa, and Alameda County shorelines. These efforts began with an evaluation of the population of native oysters and the identification of pilot sites where restoration and monitoring projects could take place. Now, active research on the most effective ways to restore the native oyster population is starting to yield results.

Dr. Bud Abbot, a scientist with the oyster working group, is pioneering the use of complex cement structures to anchor oyster beds. These structures, which he calls "Baycrete", are designed to provide a substrate for young oyster spats to attach and a greater surface area for the oyster bed to diversify and grow. Most of his current research in the San Francisco Bay is taking place at the Marin Rod and Gun Club in San Rafael, where he is quantifying the multiple benefits of using oysters as a keystone species for the bay's ecosystems.

Restoring native oyster populations in the San Francisco Bay will have significant impacts on the bay ecosystem. Oysters are filter feeders, meaning they take in murky water, filter out food, and expel clear water. Heightened clarity allows sunlight to penetrate deeper into the depths of the Bay and help a myriad of underwater plants grow. One such plant is native eel grass, which serves as habitat for many small creatures called macroinvertebrates. These macroinvertebates are then eaten by larger fish, and thus continues the web of life.

The restoration efforts in the North Bay are already creating visible benefits to the area. Scientists have observed increases in eel grass around the oyster beds, and fishermen from the Marin Rod and Gun Club have reported bigger fish swimming around the area as well as a greater number of seabirds. Scientists are currently collecting data to evaluate the purported correlation between increases in fish populations and the oyster beds.

The Watershed Project invites volunteers and school groups to join us in these exciting restoration and monitoring efforts. As a participant, you have the opportunity to collect, measure, and count oyster spats. Additionally, you will learn about experimental design, the importance of good data, and the trials and triumphs of field sampling. Most importantly you will be part of a worthwhile effort to improve the health of the Bay and its ecosystems. Our hope is that oysters in the Bay will once again be an abundant and healthy food source.