Re‐establishment of the native oyster, Ostrea conchaphila, in Netarts Bay, Oregon, USA

• Main Author: Archer, Pamela Emily
• Other Authors: Miller, Jessica, Harte, Michael, D'Andrea, Anthony, Lodwick, Camille, College of Oceanic and Atmospheric Sciences, Oregon State University. Graduate School
• Format: Master Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Olympia oyster > Ecology > Oregon > Netarts Bay; Olympia oyster > Reintroduction > Oregon > Netarts Bay; Zostera marina > Ecology > Oregon > Netarts Bay; Crassostrea gigas
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/zs25xd822

Olympia oysters, “Ostrea conchaphila,” were once common along the west coast of North America. A popular delicacy, native oyster populations began to decline in the late 1800’s due to over‐harvest, degraded water quality, and habitat loss. Interest in re‐establishing the native oyster in a small Oregon estuary, Netarts Bay, culminated in a partnership among The Nature Conservancy, the National Oceanic and Atmospheric Administration, the Oregon Watershed Enhancement Board, and Oregon State University. This study was designed to assess the reestablishment progress of the Olympia oyster restoration in Netarts Bay along with subsequent impacts of the restoration on eelgrass (“Zostera marina”), an important estuarine species. Two brood years (2005 & 2006) of cultch, consisting of O. conchaphila set on clean “Crassostrea gigas” shell substrate, were outplanted within an extensive, relatively uniform eelgrass bed. Cultch was placed in two experimental locations to determine the effect of cultch cover on native oyster survival, growth, and eelgrass abundance. The percent cover of cultch varied among treatments: “control” (no cultch), “low” (4% cultch cover), “medium” (11% cultch), and “high” (19% cultch). Research objectives were: (1) determination of O. conchaphila density, growth, and reproduction; and (2) quantification of the response of ”Z. marina” abundance and reproduction to cultch cover. Results from 2007 demonstrated that Olympia oysters were capable of growth, reproduction, and recruitment within their former habitat. Cultch cover within treatments did not change throughout the summer and there was minimal shell export out of the experimental location. Oyster size increased from March‐September, 2007: the mean size of the 2005 brood year increased by 10.5 mm, while the 2006 brood year increased by 16.2 mm. Sperm and larvae were found in individuals from both brood years, indicating that oysters were reproductively active. Declines in eelgrass mean percent leaf cover and shoot density were observed with ...