Presentation on theme: "Does knowing the History of Life in the Bay help us with its Restoration? Predicting the Future of San Francisco Bay: Learning from History Andrew Cohen."— Presentation transcript:
Does knowing the History of Life in the Bay help us with its Restoration? Predicting the Future of San Francisco Bay: Learning from History Andrew Cohen Center for Research on Aquatic Bioinvasions
Reactive Reducing Damage Preservation Active Restoration
Past abundance Why we lost it Details of nature and function Eco-historical knowledge:
Olympia oyster Ostrea lurida What does Eco-history tell us?
“These oysters were really super-abundant 150 years ago," said Edwin "Ted" Grosholz, a marine ecology specialist at UC Davis. “We know that from the harvest numbers in San Francisco Bay in the late 1800s...At one time, Olympia oysters littered San Francisco Bay.” —SF Chronicle 4/28/2003 “Historically, the native oyster (Ostrea lurida), was present in the Bay in prodigious quantities.” —Skinner 1962 “Massive shell middens formerly found around the Bay indicated that aboriginal people consumed large quantities of mollusks, particularly the native oyster Ostrea lurida…Evidence of the rapid decline of shellfish resources soon after the arrival of the white man is equally striking.” —Nichols 1979
“Gold Rush settlers found the oysters irresistible and gobbled them up so fast they were just about harvested out of existence.” —Sacramento Bee 11/26/2001 “The vast reefs of the 1800s...were smothered by gold miners' silt, poisoned by raw sewage and carved up by Barbary Coast oystermen.” — SJ Mercury News 6/8/2004 “Over-harvesting and degraded water quality have depleted the native oyster (Ostrea lurida) population in San Francisco Bay, reducing a once dominant local fishery resource to a few scattered remnant populations.”—Save The Bay Summer 2001
“In the past few years, researchers…began noticing an unfamiliar species...the native oyster of the bay, seldom seen since the 19th century. Apparently—and exactly how remains a mystery—the little native oyster hung on through the hard years of mining debris and low oxygen...in the bay.” —Booker 2006 Pacific Historical Review “The native Olympia oyster...once dominated San Francisco Bay’s ecosystem …Due to over harvesting, loss of habitat, and pollution, oysters virtually disappeared from the Bay…Indications that oysters were returning to San Francisco Bay were seen in the late 1990s when small, scattered populations were discovered on docks near Redwood City.” —submission to Journal of Shellfish Research
Native Oysters in SFBay Abundant Declined Disappeared Reappeared & Rediscovered 1700s to mid-1800s over-harvesting pollution mining sediment late 1800s-1900s 1990s
Front page part Front page of the San Francisco Chronicle, Feb. 4, 1999
Presence of Native Oysters Redwood Creek to Vallejo year% of sitescommon at 199357% of 141 199477% of 131 199679% of 141 199775% of 122
Presence of Native Oysters 1951-1979 # of # of yearrecordsyearrecords 1951319747 1962219757 1963219764 1964219771 1970519784 1971119794 19734
17941,056 1798833 1800867 18151,488 1830350 1842196 184450 1846200 1847459 1848850 18495,000 185021,000 186056,802 1870149,473 1880233,959 1890298,997 1900342,782 Population of San Francisco
Main Writings on the History of Oysters In California Barrett (1963) The California Oyster Industry Skinner (1962) Fish and Wildlife Resources of the San Francisco Bay Area Bonnot (1935) The California Oyster Industry Townsend (1893) Report of Observations Respecting the Oyster Resources and Oyster Fishery of the Pacific Coast of the United States Ingersoll (1881) The Oyster-Industry
Estimated Depth of Sediment (m) Deposited from 1870-1896 Suisun Bay & Carquinez Strait0.30 San Pablo Bay0.47 Central Bay0.00 South Bay-0.05 — based on Krone (1979)
So if it wasn’t overharvesting, or pollution, or hydraulic mining debris that did in the native oysters, then what did?