Limiting Factors in the Success of Habitat Restoration Sites for O. Conchaphila in San Francisco Bay For the: 9 th International Conference on Shellfish Restoration Charleston, SC November 17, 2006 By: Robert R. Abbott, Rena Obernolte MACTEC Engineering and Consulting Inc. & Brian Mulvey Kleinfelder, Inc.
Pilot Project Objectives n n n Demonstrate the feasibility of reestablishing selfsustaining populations Obtain data to help identify limiting factors – Substrate - Predation – Water quality - Disease – Other (circulation, population densities, larval sinks, ? ) Identify appropriate conditions and methods for reestablishment Establish connection with tidal marsh? Develop better understanding of genetics
3 Project Locations – Marin Rod and Gun Club – Bair Island – Sailing Lake
BAIR ISLAND SITE Near Redwood City In South San Francisco Bay
BAIR ISLAND FEATURES n Tidelands adjacent to tidal marsh preserve – Implications for South Bay Salt Ponds ? n n n -1 feet to -3 feet re MLLW Oyster drill 1/m 2 (Harris 2004) South SF Bay water regime – – – Long retention time Euryhaline conditions Historical native and commercial oyster utilization
OYSTER DRILLS Only observed in South Bay to date n High densities at project sites near Bair Island n Many mortalities observed (younger oysters) n Overall not much of a limiting factor n Other sources of mortalities outweigh drills n
2006 Pallet Installation
BAIR ISLAND RESULTS n n n Overall survival at the end of one year higher than other sites (a very wet year) Oyster drills have not been observed to be as limiting as other factors Used extensively by gobies, and opportunistic organisms Much increased set using hanging bags in 2 nd year – Different environment – Local oyster population now present – Predator access possibly reduced 2006 pallet shell recruited much better than 2005 pallet shell
BAIR ISLAND PROJECT ACKNOWLEDGEMENTS n NOAA Corps, NOAA Fisheries Santa Rosa, and NOAA Restoration Center Marine Science Institute USGS California Department of Fish and Game Volunteers from Save the Bay, SERC, MRGC, local residents n Funding provided by n n – US Fish and Wildlife Service – Coastal America – San Francisco Bay Joint Venture
MARIN ROD AND GUN CLUB SAN RAFAEL In North San Francisco Bay
Marin Rod and Gun Club Site n n n n n 40 Acres owned fee simple Club members committed to conservation Voted on a three year program Phase 1 -Strings Phase 2 -strings, stakes, pallets Phase 3 -Reef rows Eelgrass Recreational anglers Fish utilization study Water quality effect on survival
Project Location Map
Recreational Angler CPUE 2006
POTENTIAL LIMITING FACTORS n n n Substrate Sedimentation Salinity (depth) – Mortality – Spawning n Competition – Varies seasonally and annually n n Predation Disease ? Dissolved oxygen? Permits – Considered fill – Large projects difficult to permit (> 0. 25 acre)
FUTURE RESEARCH n n Continue studies of recruitment, growth and survival through time Establish monitoring program for predators and disease (green crabs, oyster drills, etc. ) Increase monitoring to include fish and invertebrate utilization of oyster shells and reef structures Continue trying different substrates, configurations, and variations in time and depth of placement
ACKNOWLEDGEMENTS n n n Todd Meyer Club, Jerry Mc. Eowen, Mike Guenza, Paul Tarzia and Bill Craig and the whole Marin Rod and Gun Club team Natalie-Cosentino Manning, Eric Bohaboy and everyone at the NOAA Restoration Center and NOAA Fisheries Santa Rosa Over 100 Volunteers from the Marin Conservation Corps and California Conservation Corps, and 4 Bay Area Universities, house wives, Save the Bay, etc. Students from 4 Bay Area high schools San Francisco Bay Joint Venture Kevin Lunny: Drakes Bay Oyster Farm
SAILING LAKE Shoreline Park in Mountain View South San Francisco Bay
Sailing Lake 47 acres saltwater recreational lake n Impermeable clay bottom n Built in 1982 n Up to 16’ deep n Bottom DO = 0 ppm at times n No predators n
SAILING LAKE OYSTER BED
Sailing Lake links with San Francisco Bay via pumps from inner Charleston Slough San Francisco Bay Sailing Lake
Sailing Lake Results n. Bags of cultch placed on the bottom (4 m) for 7 weeks collected approximately 4 spat per cultch shell n. The deepest bags collected the most spat n. Oysters were evaluated by CDFG before being moved n. Sailing Lake oysters appear to have better survival than natural sets at Bair Island Marine Rod and gun Club
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