The western North American bivalve mollusc known as the Olympia oyster, long known as Ostrea lurida Carpenter 1864†, is a historically exploited native species that has been largely displaced by larger nonnative oysters. There is much renewed interest in documenting and restoring its native populations and recent successful culturing has attracted a specialty market for these oysters. Yet its name was called into question when it was synonymized with O. conchaphila Carpenter 1857, an oyster whose type locality is Mazatlán, Sinaloa, Mexico. Others have considered it more plausible that the Olympia oyster is a more northern species, distinct from O. conchaphila, but morphological or molecular evidence either way has been lacking. Here we used a molecular approach to test the single versus two-species hypotheses with samples from Sinaloa, Mexico, near the type locality of O. conchaphila (Mazatlán, Mexico), and samples from Willapa Bay, WA, the type locality of O. lurida, as well as samples from intermediate locations. Based on our combined and separate analyses of two mitochondrial DNA (mtDNA) markers, 16S ribosomal RNA (16S) and cytochrome oxidase III (CO3), native Ostrea from Sinaloa, Mexico are reciprocally monophyletic with a clade from multiple other localities between Baja California, Mexico and British Columbia, Canada, including Willapa Bay, WA. Corrected pairwise sequence comparisons for 16S indicate these two groups last shared a common ancestor 1.5–3.9 mya (2.06% sequence divergence). Based on these results and assuming that the Sinaloa group represents the true O. conchaphila, molecular evidence supports O. conchaphila and O. lurida as separate species. Posthoc morphological comparisons uncovered no significant support for morphological distinction between the two taxa, underscoring the difficulty associated with using morphology alone to distinguish closely related oyster species. Despite the present lack of any morphological diagnostic differences for separating these nominal species, the molecular data are not consistent with the synonymy of the species and support the reinstatement of O. lurida from all the localities north of central Baja California.

Despite the interest in restoring remnant populations of the Olympia oyster, Ostrea lurida Carpenter 1864,† little is known about connectivity among populations. Identifying the sources of settling larvae could broaden our understanding of the degree to which particular populations are reliant on their neighbors for their persistence. Calcified structures such as the otoliths of fish and statoliths of invertebrates are increasingly being exploited as useful “natural tags” that help track individual movements and, when applicable to larvae, could help to pinpoint important source populations. In controlled laboratory culturing experiments, we explored the prospects for using the chemistry of larval shells (prodissoconchs) as natural tags of larval source by examining whether larval shells record shifts in seawater element chemistry, whether larval shells undergo ontogenetic shifts in element uptake, and whether the chemistry of the shell formed during brooding is compromised by subsequent shell thickening during the planktonic phase. Results from a two-way ANOVA examining the effect of seawater element concentration and ontogeny showed that element/ Ca in the shell increased in response to increasing seawater elemental concentrations for Ba, Ce, Pb, and Mn, whereas shell Cu/Ca did not change. Ostrea lurida shell chemistry also showed strong ontogenetic shifts in element/Ca for Mg, Sr, and Cu during the transition from larva to settler. Settler shell Mg/Ca strongly increased compared with planktonic shell, whereas Sr/Ca and Cu/Ca showed the opposite pattern. Further, the chemistry of the shell formed during brooding (at the birth location) did change as a function of environmental conditions experienced during the planktonic phase for the elements Ba and Ce, but that change was limited to regions of the brooded shell just adjacent to the planktonic shell. When the brooded portions of larval shells were sampled closer to the umbo, the brooded shells' chemistry remains intact. The combined results suggest that larval Ostrea lurida shells act as recorders of environmental change and show promise as tools to track larval movements.

The Olympia oyster (Ostrea lurida)^† is a prime candidate for the development of a rapid, high throughput, species-specific larval identification and quantification assay. We developed O. lurida specific DNA primers and a fluorescently labeled probe that amplify a mitochondrial DNA region cytochrome oxidase 1 subunit (COI) to use in quantitative polymerase chain reaction (qPCR). We also developed qPCRs for the specific detection of Neotrypaea californiensis and Upogebia pugettensis, two burrowing shrimp species that have been shown to have a negative effect on oyster bed habitat. The primer and probes amplified only the target organisms. Using standard curves constructed from known quantities of larvae, we are able to rapidly and accurately identify and estimate unknown quantities of larvae. In blind tests, direct counts of O. lurida larvae did not significantly differ from qPCR estimates. DNA was fully liberated from up to 80 O. lurida larvae, and 10 N. californiensis larvae; PCRs were not inhibited as demonstrated by an internal positive control multiplexed into the qPCRs. Genetic based assays are an extremely useful method for sorting complex plankton samples that can be more time and cost effective than traditional microscopy techniques. Our qPCR assay may prove to be a valuable tool to monitor O. lurida restoration site productivity as well as increase our understanding of this critical life history stage.

Overexploited fisheries are a worldwide problem. Restoration efforts aimed at these fisheries often involve a combination of reduced catch, hatcheries, and habitat improvement. The native oyster of western North America, Ostrea lurida,† was commercially extinct in most locations more than a century ago. In this paper, we track the history of its management for insight into its demise and failed recovery in Washington State. We document six phases of management: open access, aquaculture, control of water pollution sources, substitution by nonindigenous oysters, harvest regulations and marine reserves, and restoration. Three general lessons emerge from this historical analysis, which may apply generally to exploited fisheries that fail to recover. First, the introduction of substitute species led to neglect of the native species for many decades. Second, reserves were not fully protected and instead were designed for commercial removal of newly settled oysters, thus they largely failed. Finally, current restoration efforts are hampered by several biological problems, including water pollution, invasive competitors and predators, and habitat loss.

Historical evidence indicates that Olympia oysters (Ostrea lurida)^† are indigenous to at least three of Oregon's estuaries. Populations of O. lurida occur in Yaquina Bay, Netarts Bay, and Coos Bay, although only the population in Yaquina Bay seems likely to have been continuous since prewestern settlement. The historical occurrence of Olympia (native) oysters in Yaquina and Netarts Bays is confirmed by numerous records of fishery landings. In contrast, historic populations in Coos Bay are inferred by the presence of large shell deposits buried in sediments throughout the polyhaline (salinity > 18–30) region of the estuary. Other Oregon estuaries (such as Tillamook, Alsea, and Umpqua/Winchester Bay) may have had ambient environmental conditions suitable to support self-sustaining populations of O. lurida, but none of these estuaries are currently inhabited by natural populations, nor do they exhibit clear historical records of occupation in the past. We conducted searches of background information on many estuaries to summarize knowledge about the status of O. lurida populations in Oregon. The information presented here is based on a literature search, analysis of internal agency documents, and personal contacts with individuals most familiar with specific estuaries. As a case study, the Oregon Department of Fish & Wildlife (ODFW) repeated intertidal field surveys previously conducted in 1997 in an effort to document changes in O. lurida populations within Coos Bay. Field surveys conducted in 2006 followed methods that were similar to the 1997 intertidal surveys. Using previously published results as a baseline, we found that populations of native oysters exhibited spatial expansion throughout the mesohaline and polyhaline regions of the estuary, and that the intertidal oysters occurred at increased densities, over a wider range of sizes, and over a broader range of habitats. Further recovery of O. lurida populations in other regions of Coos Bay is most likely limited by the availability of suitable substratum for attachment and growth of the juvenile oysters.

The Olympia oyster, Ostrea lurida Carpenter 1864,^† is the only oyster native to British Columbia. Once the focus of a fishery, they have not been commercially harvested since the 1930s because of stock declines and a shift in focus to nonindigenous oysters. Olympia oysters were reported from Juan de Fuca Strait, Strait of Georgia, West Coast Vancouver Island, Queen Charlotte Strait and North Coast areas to approximately 52°13′N. They were only characterized as abundant at sites in the North Coast and West Coast Vancouver Island. Systematic quantitative sampling has not been undertaken in BC, but the few sites surveyed had estimated densities higher than others in the literature. Biological sampling was also rare in BC, and size distributions suggest that regular, low level recruitment occurs at some sites. The low incidence of brooding oysters is likely an artifact of sampling too soon in the reproductive season. Olympia oysters were listed as special concern species by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in 2000 and under the Canadian Species At Risk Act (SARA) in 2003. Some measures have been taken to protect Olympia oysters from further decline: no commercial fishery exists or is contemplated at this time, the bag limit in the recreational fishery was reduced to zero in 2007, regulations are in place and proposed that will prohibit the use of tributyltin antifouling paints in Canada and basic protection is afforded within Federal and Provincial parks. A management plan is required under SARA by June 2008.

Despite the recently renewed interest by ecologists and government agencies to reestablish historical populations of the Olympia oyster, focus has been limited to projects located at the north of this species' range, with little or no attention to southern California and Baja populations. In addition, historical information on the status of natural populations across the range has been mainly qualitative in nature, with no comprehensive information on the current status of natural populations. The focus of this study was to conduct the first large-scale quantitative biogeographic survey of remnant populations of the Olympia oyster and to identify suitable sites in southern California for future restoration projects. We surveyed intertidal populations at 24 historical sites during spring and summer 2005 and summer 2006, established presence/absence and collected data on densities and percent cover. Average maximum densities ranged from 0.0–36.7 ± 12.1 oysters per 0.25 m². In southern California, intertidal populations were present in all bays and estuaries south of Morro Bay and most showed evidence of regular recruitment. Thus, all southern California sites could present favorable opportunities for restoration projects. At the north end of the range, intertidal populations were more often absent from sites, though there was evidence of subtidal populations. Populations were absent from intertidal sites at the northern endpoint of its distribution in Sitka, Alaska. We speculate that the current northern range limit of this species is located in northern British Columbia. Intertidal populations were also absent at two CA sites, Morro Bay, and Big Lagoon; anecdotal evidence further suggests that subtidal populations were also absent. This study represents the first comprehensive biogeographic survey of intertidal populations of the Olympia oyster, Ostrea lurida^†, and identifies sites in southern California as suitable locations for future restoration projects.

The Olympia oyster, Ostrea lurida,† is native to the Pacific Coast of North America and was common in Puget Sound prior to the arrival of European settlers. Over harvest in the late 1800s, combined with severe pollution in the first half of the 20th century from pulp mills, drove many Puget Sound beds to near extinction. Olympia oysters can still be found throughout most of their historic range, but current populations are mostly limited to remnant aggregations where habitat characteristics remain favorable. Whereas Olympia oysters are still present in Puget Sound, their numbers do not compare with the expanses of Olympia oysters that supported a thriving oyster industry in the mid-1800s. One reason for rebuilding Olympia oyester populations is to regain the ecosystem benefits associated with larger assemblages. Skagit County Marine Resources Committee, working in cooperation with shellfish industry, tribal, and community partners initiated a project to establish self-sustaining Olympia oyster beds in Fidalgo Bay near Anacortes, WA. Thus, oysters on these beds must survive, grow, spawn, and produce larvae that recruit to the new beds and surrounding areas. Olympia oyster seed on Pacific oyster cultch were planted in Fidalgo Bay during 2002, 2003, 2004, and 2006. Survival and growth of planted seed has been excellent at the first enhancement site. With the addition of seed on cultch during four years and augmentation of the enhancement site with five cubic yards of Pacific oyster shell in 2006, a structured oyster bed is gradually emerging. Deployment of temperature sensors in 2006 showed that water temperatures easily reached the minimum temperature for gameteogenesis and spawning. Examples of larval spawning (veligers in the mantle cavity) and natural postlarval recruitment to the enhancement site were documented in 2006. Several new sites within and around Fidalgo Bay are being evaluated for future rebuilding efforts.

The Olympia oyster (Ostrea lurida)^‡ was historically abundant in Willapa Bay, WA, but populations were decimated by overexploitation in the mid to late-1800s and have failed to recover. We investigated the potential role of two introduced predatory gastropods, the Japanese drill (Ocinebrina inornata) and the eastern drill (Urosalpinx cinerea), in limiting Olympia oyster recovery. We quantified the bay-wide distribution, local abundance, and per capita effects of drills, and asked how each of these three components of total invasion impact might be influenced by another dominant introduced species, the Pacific oyster (Crassostrea gigas). Bay-wide sampling revealed differences in spatial distribution of the two drill species, with U. cinerea more abundant toward the head of the estuary and O. inornata more abundant toward the mouth. Individual feeding trials indicated that both drill species preferred Pacific oysters to Olympia oysters of similar size, and preferentially attacked smaller oysters. We used field enclosures to quantify the direct effects of Japanese drill predation on Olympia and Pacific oysters, intra and interspecific competition, and indirect effects mediated by the shared predator. Predation reduced the survival of both oyster species, but the per capita impact of Japanese drills declined with increasing density of either Olympia or Pacific oysters, consistent with a type II functional response. This positive indirect effect of Pacific oysters on Olympia oysters was offset by asymmetric competition, in which Pacific oysters reduced Olympia oyster growth and survival but not vice versa. Despite the large drill impacts seen in these experiments, Olympia oysters transplanted to intertidal sites throughout the bay experienced low and variable rates of drill predation compared with other mortality sources. Introduced drills may be only one of a suite of factors that prevent rebuilding of Olympia oysters in the intertidal zone in Willapa Bay.

The Olympia oyster, Ostrea lurida Carpenter 1864,^† in estuaries along the Pacific coast of North America, experienced overexploitation throughout its range in the late 1800s, resulting in commercial extinction before 1930. Significant harvest restrictions and marine reserves were established in Washington State by 1897 to protect new recruits, and harvest pressure has been negligible for the past 80 y. Nevertheless, O. lurida remains locally rare. This study focuses on the contemporary dynamics of the remnant population of O. lurida in Willapa Bay, Washington, historically home to the largest native oyster fishery on the coast, with a broad focus on factors preventing recovery. Failed recovery could be because of reproductive limitation, or to poor postrecruitment performance. In this case, reproductive limitation seems unlikely, because historical (1947 to 1983) and modern (2002 to 2006) records reveal 5-fold higher annual spatfall for O. lurida than introduced Pacific oysters (Crassostrea gigas.) However, O. lurida remains rare and C. gigas is commercially exploited from natural recruitment. To evaluate the effects of abundant C. gigas in intertidal areas on O. lurida settlement patterns, strings of C. gigas shell were placed at two tidal elevations in three habitat types—open mud, eelgrass beds of Zoster a marina, and C. gigas reefs. Settlement of O. lurida was significantly higher on the shell strings placed in the C. gigas reefs at both tidal heights. To evaluate postrecruitment demography, juvenile O. lurida were outplanted at three tidal elevations at five sites, and fouling organisms were manipulated to test for competition. Short emersion times (8% greater exposure) reduced survival by 80% relative to subtidal treatments, but did not affect growth rates of survivors. Naturally-setting competitors, mostly nonindigenous, depressed survival by 50% and growth by 20%. In a third experiment, manipulating the density and stability of shell substrate, O. lurida was easily moved or buried when outplanted in a thin, unconsolidated layer. These results indicate that recovery has been hampered by the removal of dense subtidal native oyster shell accumulations during exploitation, by direct competition from exotic species, and by the appearance of novel introduced oyster shell settlement substrate in the intertidal zone. This altered web of interactions influencing O. lurida serves as a model for beginning to explore the failed recovery of overfished species in rapidly changing coastal systems.

The Olympia oyster of Washington State, USA (Ostrea lurida^†) was heavily exploited (1850 to 1940), declined dramatically, and has subsequently failed to recover, although it still supports small aquaculture operations. This paper documents the distribution and abundance of O. lurida in one of the last remaining locations where it forms extensive beds: the North Bay Oyster Reserve in south Puget Sound. We monitored recruitment every 2 wk between May and September 2004 and found a small recruitment peak in late July, which was much later than reported for these oysters when they were abundant throughout Puget Sound. We also experimentally tested two factors that could influence recovery: tidal elevation and substrate type. We established 1 m² plots at three tidal elevations (-0.3, 0, 0.3 m MLLW) with six substrates: bare, gravel, crushed shell of Crassostrea gigas (Pacific oyster), whole C. gigas shell, whole shell of O. lurida, and live O. lurida. The plots were set up May 21, 2004 and measured for recruitment on October 16, 2004 and April 11, 2005 by collecting material from a 0.0125-m² area of each plot. Recruitment improved at low tidal elevations and differed across substrates. Ostrea lurida shell consistently provided a better recruitment substrate than gravel or bare plots, but shell treatments could not be distinguished statistically. Postrecruitment mortality occurred in all treatments; however the rates of mortality were not significantly different by elevation or substrate treatment. Habitat restoration (low intertidal and subtidal shell areas) should promote the recovery of O. lurida where natural recruitment still occurs.

The continued lack of recovery of the United States west coast populations of the Olympia oyster, Ostrea lurida† Carpenter 1864, has piqued recent interest in restoration projects. Because local population persistence is influenced by many factors, including larval settlement, information about the magnitude and timing of settlement will provide valuable contributions to such restoration efforts. We examined larval settlement as a function of season and also monitored water temperature, which is reported to influence settlement timing by cueing synchronized male spawning and subsequent larval settlement. Previous literature, based on an anomalous open coast population, found that settlement of O. lurida in La Jolla, CA occurred once seawater reached a temperature of 16°C. To observe variation over seasons in larval settlement density relative to temperature within the more common estuarine habitat in southern California, we placed ceramic tiles in two locations within Upper Newport Bay, Newport, California and in two locations within Aqua Hedionda Lagoon, Carlsbad, California. Temperature data were also collected at each site throughout the sampling period. Tiles were collected and oyster spat counted every two weeks during spring tides to pinpoint pulses in settlement. Settlement in Upper Newport Bay occurred from May until November with peak settlement in June and ranged from 0.0 oysters/m² to 1,179 ± 344.8 oysters/m² at Coney Island and 0.0 oysters/m² to 511 ± 216.4 oysters/m² at Newport Wall. In Aqua Hedionda Lagoon, settlement occurred from June until February with peak settlement in June and ranged from 0.0 oysters/m² to 339 ± 53.7 oysters/m² at Aqua Hedionda site 1 and 0.0 oysters/m² to 108 ± 37.3 oysters/m² at Aqua Hedionda site 2. Whereas oyster settlement did occur at all of our study sites, we did not observe a universal temperature that correlated with the initiation and termination of oyster settlement, nor any significant correlations linking water temperature with peaks in settlement.

As interest and efforts in ecological restoration of native bivalve populations grow, the genetic implications of various restoration strategies are often unclear to resource managers and restoration practitioners, even though genetic considerations are vital to the ultimate success or failure of restoration endeavors. In an effort to fill this void, we present an overview of the underlying genetic concepts, a brief review of documented examples of native mollusc populations impacted by hatchery production, and a summary of the potential genetic impacts of restoration activities ranging from eliminating ongoing negative impacts with minimal genetic effects to intentional genetic manipulation of extant populations. We emphasize throughout the importance of understanding how adaptive, quantitative genetic variation is distributed within and among populations and the limitations of studies that address only selectively neutral molecular genetic variation. We also describe a conceptual framework for making genetically sound management and restoration decisions based on historical and current ecological and genetic considerations. Finally, because fully-informed decisions require a great deal of difficult-to-obtain data, we make suggestions on how to prioritize future research and outline practical measures that can be implemented in the absence of rigorous genetic data to prevent inadvertent negative genetic impacts by well-intended restoration efforts.

Reefs and beds formed by oysters such as the Eastern oyster, Crassostrea virginica and the Olympia oyster, Ostrea lurida Carpenter 1864^† were dominant features in many estuaries throughout their native ranges. Many of these estuaries no longer have healthy, productive reefs because of impacts from destructive fishing, sediment accumulation, pollution, and parasites. Once valued primarily as a fishery resource, increasing attention is being focused today on the array of other ecosystem services that oysters and the reefs they form provide in United States coastal bays and estuaries. Since the early 1990s efforts to restore subtidal and intertidal oyster reefs have increased significantly, with particular interest in small-scale community-based projects initiated most often by nongovernmental organizations (NGOs). To date, such projects have been undertaken in at least 15 US states, for both species of dominant native oysters along the United States coast. Community-based restoration practitioners have used a broad range of nonmutually exclusive approaches, including: (1) oyster gardening of hatchery-produced oysters; (2) deployment of juvenile to adult shellfish (“broodstock”) within designated areas for stock enhancement; and (3) substrate enhancement using natural or recycled man-made materials loose or in “bags” designed to enhance local settlement success. Many of these approaches are inspired by fishery-enhancement efforts of the past, though are implemented with different outcomes in mind (ecological services vs. fishery outcomes). This paper was originally presented at the first West Coast Restoration Workshop in 2006 in San Rafael, California and is intended to summarize potential approaches for small-scale restoration projects, including some emerging methods, and highlight the logistical benefits and limitations of these approaches. Because the majority of the past efforts have been with C. viriginica, we use those examples initially to highlight efforts with the intent of enlightening current west coast United States efforts with Ostrea lurida. We also discuss site-specific characteristics including “recruitment bottlenecks” and “substrate limitation” as criteria for identifying the most appropriate approaches to use for small-scale restoration projects. Many of the included “lessons-learned” from the smaller-scale restoration projects being implemented today can be used to inform not only large-scale estuary wide efforts to restore C. virginica, but also the relatively nascent efforts directed at restoring the United States west coast's native Olympia oyster, Ostrea lurida.

Oyster shell may be taken from one bay and placed in another for a variety of purposes, including the restoration or enhancement of native oysters or other native species. Whereas it is generally appreciated that undesirable organisms can be transferred with live oysters, oyster shells alone can also serve as vectors for the accidental introduction of marine organisms to new locations. We here describe oyster shell plantings made for various purposes, the potential for these plantings to inadvertently transfer live organisms, and biosanitary procedures that could limit these transfers.