Oysters Come Back After Humans Ate So Many They Disappeared
It only took one century for “ravenous San Franciscans” to catch and devour so many oysters that they disappeared from the waters where they had lived for millennia. In 1893, Olympia oyster beds covered 8,033 acres — about a half-million per acre — in Newport Bay, Elkhorn Slough, San Francisco Bay and Humboldt Bay but by 1911, all the region’s native oyster beds had disappeared.
Thanks to the good work of conservationists, oysters are coming back to the Bay, says SFGate. Over the past year, two million oysters have settled on human-made reefs composed of mesh bags filled with discarded shells from Drakes Bay Oyster Co.
These oysters are not for human consumption. For one thing, the Bay’s waters are too polluted. The return of the oysters has more than a few benefits: oyster reefs play a crucial role in marine and ecosystems as they form a natural protective barrier that can help to protect the shoreline and lessen problems resulting from a rise in sea level. Researchers have already found a 30 percent reduction in wave energy at the site of the oyster reefs in comparison to a control area.
Oysters also play a key role by filtering water, removing nitrogen and other pollutants; just one oyster can filter 30 gallons of water a day. Their reefs also provide a habit for fish, crab and other marine creatures. Marilyn Latta, the project manager for the Living Shorelines Project and the California State Coastal Conservancy, tells SF Gate that there are more juvenile Dungeness crab, bay shrimp and rock crab in the test area. Many more birds — black oyster catchers, great egrets and great blue herons — have also been seen at the site, a sign that there are more fish in the water.
The five-year, $2 million effort was undertaken by the California Coastal Conservancy and is part of the San Francisco Bay Living Shorelines Project. Two one-acre mounds of shells (one in San Rafael near the Richmond-San Rafael Bridge and the other one south of the San Mateo Bridge in Hayward) are serving as test sites.
Plenty of challenges lie ahead to maintain the oyster reefs and even create new ones. The Gold Rush not only brought in an influx of people but left silty bay mud in the waters and pollution is a persistent problem. Another issue is an invasive species, a small and predatory snail, the Atlantic oyster drill, which arrived via shipments of Atlantic oysters.The snail drills its way into oysters’ shells and sucks out their insides.
The Olympia oyster once filled subtidal waters from Southern California all the way up to southeastern Alaska. Native American midden sites — rubbish piles containing oyster shells as well as bones and antlers — in the San Francisco Bay date back to around 4,000 years ago and show how plentiful the oyster population was, until humans’ excessive consumption of the reefs.
Like the bluebuck in southern Africa, the Great Auk and passenger pigeons, the Olympia oyster was wiped out because of humans’ highly irresponsible and ignorant actions. The oysters’ return shows that, via conservation efforts, we can bring back species from the brink. This time around, let’s make sure that everyone knows the value of the oysters not as food, but as a key member of the ecosystem of the San Francisco Bay.
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