Invasion
Invasion Description
Recent 1st Record: Dumbarton Railway Bridge/CA/South San Francisco Bay (2000, Andy Chang, personal communication, Goodwin et al. 2011; Ruiz et al. unpublished data, possibly established populations).
Historical 1st Record: CA/Tomales Bay (1928, failed as a breedin population, but commercial culture, 1932 to present, Carlton 1979, Conte 1996)
Since 2000, the settlement of large oysters, apparently M. gigas has been observed in San Francsco Bay. In 2006, more than 100 of these oysters were removed in a control attempt (2006, USGS Center for Aquatic Resource Studies 2006). Shell isotope studies indicate that at least two successful cohorts were established (Goodwin et al. 2011).
Geographic Extent
CA/Bodega Harbor (commercial plantings 1932-1938; Barrett 1963, cited by Carlton 1979); CA/Tomales Bay (1st planted 1928, Barrett 1963, cited by Carlton 1979, occasional reproduction observed, 1974, Span 1978, commercial operations continue to present, Conte 1996); CA/Drakes Estero (failed, commercial culture, 1932 to present, Carlton 1979, Conte 1996); CA/Bolinas Lagoon (1st planted 1955, failed, Barrett 1963, cited by Carlton 1979); CA/San Francisco Bay (1st planted 1932 to 1939, Barrett 1963, cited by Carlton 1979); Dumbarton Railway Bridge/CA/South San Francisco Bay (2000, Andy Chang, personal communication, Ruiz et al. unpublished data, established populations, Goodwin et al. 2011); Eastern shore of South Bay from Dumbarton Point to Coyote Slough/CA/San Francisco Bay (2006, USGS Center for Aquatic Resource Studies 2006); CA/Elkhorn Slough (failed, 1st planting 1929, commercial operations continuing to 1980s, Wasson et al. 2001); CA/Morro Bay (1st planting 1932, population status unknown, commercial operations continuing, Carlton 1979, Morro Bay National Estuary Program 2005 http://www.mbnep.org/index.php; Conte 1996)
Vectors
| Level | Vector |
|---|---|
| Alternate | Oyster Intentional |
| Alternate | Ballast Water |
| Alternate | Hull Fouling |
Regional Impacts
| Economic Impact | Fisheries | |
| Commercial oyster operations, using M. gigas began in Tomales Bay in 1928, and continue to the present. Major locations of oyster rearing included Morro Bay, Elkhorn Slough, Drakes Estero, and Tomales Bay (Barrett 1963; Carlton 1979; Conte 1996). Culture of M. gigas continues in Morro Bay, Drakes Estero and Tomales Bay (Conte 1996). In San Francisco Bay, commercial Pacfiic Oyster rearing occurred form 1932 to 1939. Oyster culture here was intially dependent on seed imported from Japan, but now uses seed produced in US hatcheries (Barrett 1963, Conte 1996). California Pacific Oyster growers produced 1.5 million pounds of shucked meat in 1995. About 90% of Calfornia's production occurred in Drakes Estero and Humboldt Bays (Conte 1996). | ||
| Ecological Impact | Parasite/Predator Vector | |
| Parasite-Predator vector- Although M. gigas has not become definitely established in central California, its introduction has been a possible/probable vector for a number of oyster foulers or predators, including Pteropurpura (=Ocinebrellus) inornata (Japanese Oyster Drill) in Tomales Bay, the parasitc copepod Mytilicola orientalis (widespread), the mussel Musculista senhousia, the bryozoan Schizoporella japonica, and the tunicates Botrylloides violaceus, Didemnum vexillum and Styela clava (Carlton 1979; Cohen and Carlton 1995; Wasson et al. 2001; de Rivera et al. 2005). | ||