There was a time when the San Francisco Bay was replete with native oysters. But it's been many years now since they were contaminated and fished out. As part of efforts to restore the Bay, Andrea Kissack of KQED reports scientists are trying to bring back these useful and sought-after mollusks.
CURWOOD: It's Living on Earth. I'm Steve Curwood and coming up: The powers of observation made keen by a life behind bars.
But first, San Francisco Bay is one of the world's most popular places. But that popularity has come with a cost: gold mining runoff, dredging and development have killed many native species that once thrived in the bay. Now, an ambitious plan is underway to restore it to its natural state. And one critical step is to bring back a tiny, native shellfish. Andrea Kissack has more.
[OYSTERS BEING SHUCKED AND SLURPED DOWN]
KISSACK: The lunch crowd at Hog Island Oyster Company on the famous San Francisco wharf slurps down oysters just as fast as the waiters can shuck ‘em. But these oysters didn't come from the bay, just a few feet away. They were hauled down from another body of water, 60 miles north--Tomales Bay. There was a time when you could eat native oysters right out of San Francisco Bay. For generations the mollusks fed the Coast Miwok and Ohlone Indians.
KISSACK: In the late 1800s, it was the gold miners' voracious appetite for the native Olympic oyster that made the Bay Area the capital of the west coast oyster industry. Jack London even memorialized the abundant oyster in his short stories. But by the time of London's death in 1916, San Francisco oysters were mostly gone, choked off by the city's raw sewage or over-fished. The oysters that survived were imported from Seattle or hauled by train from the East Coast and dumped on top of the old San Francisco oyster beds. But by the 1940s, even the non-native oysters couldn't survive in San Francisco's increasingly polluted bay.
[SOUND OF SLOSHING WATER]
MCGOWAN: Well, the last time I tried this I sank to about my knees walking through this mud.
KISSACK: In the shallow waters off Tiburon, in the northern part of the bay, Marine biologist Mike McGowan sloshes through four feet of quick sand like sludge, washed down from upstream.
MCGOWAN: This mud, which is a legacy of the hydraulic mining, gold mining in the Sierras is still here in the bay.
[SOUND OF WADING IN WATER]
KISSACK: McGowan is trying to find one of his oyster beds. Last spring, volunteers helped him sink clusters of empty oyster shells off this shore in hopes they would become homes for baby oysters. A larger scale effort is succeeding in Chesapeake Bay. But while that experiment aims to revive the eastern oyster industry, McGowan hopes to save San Francisco Bay and bringing back the oyster may be the key.
MCGOWAN: Everything is interrelated. The oysters help the eel grass, the eel grass helps the oysters. Having more oysters and eel grass means there is more habitat and shelter for fish.
KISSACK: When the whole bay ecology improves crabs, starfish and birds benefit too. Oysters are also the lungs of the bay. Just one can filter more than 15 gallons of water a day, enough to nearly fill a bathtub. So, more oysters mean cleaner water and more life in the bay.
MCGOWAN: The first thing we are going to do is walk out to that oyster reef. Turn it upside down.
KISSACK: It's low tide on a sunny Thursday morning and McGowan is slogging through the mud flats to reach one of several white buoys. This one is floating about 40-feet off shore. Anchored to the buoy is a sunken wooden pallet with about a dozen nylon mesh bags stacked and tied together. The bags are full of oyster shells. When they are very young, oysters are searching for something hard to cement themselves.
MCGOWAN: They will recruit onto just about anything--wood, old batteries' cases, shopping carts, but they greatly prefer other oyster shell because a good place to land for a young oyster is where adult oysters have already managed to grow up and survive.
KISSACK: When they find a home, oysters stick to it for life. They are much more adventuresome when it comes to their sex lives. Oysters are hermaphrodites, beginning life as males but changing to females to spawn hundreds of thousands of larvae. And back and forth they go, spending the rest of their lives switching genders. Meanwhile the pin-head sized oyster larvae are carried by the currents of the bay. And McGowan is, well, hoping to catch their drift. While some of his early tries failed, today he finds what he's looking for.
MCGOWAN: Ok, now here's an oyster, this is really great. I have looked at three shells and Brooke, how many have you looked at? Four? OK, so seven shells, on the eighth shell we found a large, native oyster, oh, there's another one.
KISSACK: McGowan searches 100 shells and finds 23 baby oysters. With the help of volunteers from the Tiburon Audubon Center, he carries them to shore and measures each one.
MCGOWAN: 2.5 centimeters.
KISSACK: At two months old, these oysters are just beginning to grow their own shells, inside the ones they've found. It's the way they've been doing it for millennia. This is one of several projects funded by the National Oceanic and Atmospheric Administration. McGowan, the Tiburon Audubon Center and local conservation groups are counting on the resilience of nature to bring back the oysters.
MCGOWAN: One way to look at it is that each isolated, small population of oysters is like a little light bulb. When the larvae from one population find a good place and settle, that's like a light bulb turning on, but then one of these light bulbs is turning off some place else. So what we'd like to do is have enough light bulbs blinking on and off around the bay that it's a continuos glow and the oyster population makes a comeback and does it on its own.
KISSACK: McGowan is hoping that happens in his lifetime. And if the bay's native oyster does return, we may find that sometimes we can reverse some of the damage we've caused. For Living on Earth, I'm Andrea Kissack in San Francisco.
[WADING IN THE WATER]
[MUSIC: Birdsongs of the Mesozoic "Swamp" Dancing on A'A (Cuneiform) 1995]
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