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Restoration Guidelines for Shellfish Reefs
Abstract and Figures
This guide is for practitioners, managers and community members to provide both guidance in decision-making for establishing shellfish reef restoration projects and examples of different approaches undertaken by experienced practitioners in a variety of geographic, environmental and social settings.
The guide both updates and expands on the original Practitioners Guide (Brumbaugh et al.), capitalising on the improvements in knowledge around the ecological function of bivalves in their coastal environments as well as on the depth and breadth of experience that now exists globally.
The restoration approach is aligned to the Society for Ecological Restoration's International standards for the practice of ecological restoration and was developed by a global team of writers and editors.
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... Oyster reefs are an essential type of marine habitat that provides a wide variety of ecosystem services, such as providing food, improving water clarity [4], facilitating denitrification [5], protecting shorelines [6], increasing landscape diversity [7,8], and providing habitats for marine life [9][10][11]. Therefore, because of their large impacts and ability to transform ecosystems, oysters are known as "ecosystem engineers" [12]. ...
... In addition to the USA, New Zealand, Australia, some European countries, and China have also researched and applied oyster reef restoration practices [3]. To provide ideas and basic information for the whole process of reef restoration project, Fitzsimons et al. [12] published shellfish reef restoration guidelines based on the latest global scientific research achievements and practical experience. ...
... Like VIMS, the global headquarters of the TNC is located in Virginia. In addition to research articles, TNC has pioneered and conducted many works on oyster reef conservation and restoration, and on top of publishing the aforementioned Shellfish Reefs at Risk [53], Oyster Habitat Restoration Monitoring and Assessment Handbook [54], and Setting Objectives for Oyster Habitat Restoration Using Ecosystem Services: A Manager's Guide [55], they released the Restoration Guidelines for Shellfish Reefs in 2019 [12] and Research Report on Conservation and Restoration of Oyster Reef Habitats in China in 2022 [3], among others. In addition, TNC has contributed to relevant conservation and restoration activities in various countries, notably by leading or collaborating in more than 200 oyster reefs and other shellfish reef restoration projects worldwide [3], including in the USA, China, Australia, New Zealand, and Germany. ...
The ocean is the largest reservoir on Earth. With the scarcity of water resources, the destruction of the benign cycle of the marine ecosystem would seriously impact people’s quality of life and health. Oyster reefs, the world’s most endangered marine ecosystems, have been recognized as a global issue due to their numerous essential ecological functions and provision of various ecosystem services. As a result, interest in oyster reef research has been steadily increasing worldwide in recent decades. The goal of this study is to assess the knowledge structure, development trends, research hotspots, and frontier predictions of the global oyster reef research field. Based on 1051 articles selected from the Web of Science Core Collection from 1981 to 2022, this paper conducted a visual analysis of oyster reef ecosystems conservation, restoration, and management. Specifically, it examined research output characteristics, research cooperation networks, highly cited papers and core journals, and keywords. Results indicate a steady rise in research interest in oyster reefs over the past 40 years, with notable acceleration after 2014. Authoritative experts and high-impact organizations were also identified. This paper outlines habitat conservation and restoration, ecosystem services, and the impacts of climate change as the primary research hotspots and frontiers. This paper provides valuable guidance for scholars and regulators concerned about oyster reef conservation to conduct research on oyster reefs.
... Moreover, restoration efforts often exist within dynamic, crowded seascapes, so stakeholder engagement, sitespecific logistics and local feasibility are also key in determining the suitability of a site for native oyster restoration. Although such factors have typically been tackled within ongoing project management (Schuster & Doerr, 2015;Fitzsimons et al., 2019), gauging stakeholder opinion and logistical challenges are critical from early on in site selection. Indeed, recent site selection activities in western Australia also include such factors in their site selection processes (Cook et al., 2022). ...
... Site selection for native oyster habitat restoration projects has been identified as a priority research area (Pogoda et al., 2020a;zu Ermgassen et al., 2020a). While there are many examples of site selection for native oyster habitat restoration across a range of spatial scales, and existing guidelines provide broad themes for consideration (Fitzsimons et al., 2019;Preston et al., 2020a), a comprehensive overview of the many considerations which should be accounted for in site selection is currently lacking. To support more efficient and successful restoration practices, this study uses the Delphi process to draw upon pan-European expertise to identify the most important factors in site selection for European native oyster habitat restoration projects. ...
... The listed factors were proposed based not only on the experts' experience with site selection processes to date, but also incorporating their experience of managing projects, and their understanding of facilitating factors in project success. The resulting list of factors therefore provides a comprehensive overview of not only the key abiotic factors which may be included in habitat suitability modelling, but also factors relating to project logistics (Figure 3b), biotic (Figure 3d) and socio-economic factors (Figure 3e), which are critical in project planning and execution(Fitzsimons et al., 2019;Preston et al., 2020a). The listed 'Essential' socioeconomic factors, such as stakeholder interest and support(Figure 4), underpin project acceptance and can be pivotal in acquiring funding, project approval and/or social licence to operate(Imeson & van den Bergh, 2006;Deitch et al., 2021;Lupp et al., 2021). ...
The European native oyster ( Ostrea edulis ) is a threatened keystone species which historically created extensive, physically complex, biogenic habitats throughout European seas.
Overfishing and direct habitat destruction, subsequently compounded by pollution, invasive species, disease, predation and climate change have resulted in the functional extinction of native oyster habitat across much of its former range.
Although oyster reef habitat remains imperilled, active restoration efforts are rapidly gaining momentum. Identifying appropriate sites for habitat restoration is an essential first step in long‐term project success.
In this study, a three‐round Delphi process was conducted to determine the most important factors to consider in site selection for European native oyster habitat restoration projects.
Consensus was reached on a total of 65 factors as being important to consider in site selection for European native oyster habitat restoration projects. In addition to the abiotic factors typically included in habitat suitability models, socio‐economic and logistical factors were found to be important. Determining the temporal and spatial variability of threats to native oyster habitat restoration and understanding the biotic factors present at a proposed restoration site also influence the potential for project scale‐up and longevity.
This list guides site selection by identifying: a shortlist of measurable factors which should be considered; the relevant data to collect; topics for discussion in participatory mapping processes; information of interest from the existing body of local ecological knowledge; and factors underpinning supportive and facilitating regulatory frameworks.
... In the case of the well-studied example of coral restoration, Ladd et al. (2018) suggest that it is important to collect data on density, diversity, and identity of transplanted corals, site selection, and transplant design. For shellfish reef restoration, recently published guidelines suggest that restoration projects should address shellfish recruitment, substrate type and limitation at the site, physical conditions, the provenance of the shellfish to be transplanted, and possibility of disease (Fitzsimons et al. 2019). The specific species of shellfish to be restored will also be important. ...
... The sheer number of agencies practitioners are required to consult adds to the amount of time it takes to seek permits: one participant's project involved interacting with four different local councils, as well as six separate state government agencies (P2). It also means that practitioners are sometimes required to strongly advocate for their projects, as they are not interacting with staff trained in restoration work (Fitzsimons et al., 2019). This in turn adds a further time burden (P4). ...
To meet global restoration targets, action is needed at a large scale, and at a high level of ambition. Coastal and marine restoration may be hindered by an array of factors, including governance: in particular, the cost and time associated with obtaining permits. We interviewed a small group of restoration practitioners in Australia to further explore this permitting issue. Our study revealed a deeper problem, with the legal permitting process driving outcomes. Some proponents are turning away from the sites with the highest restoration potential, and instead choosing sites based on the ease of obtaining permits. We also found that the permitting process is only one part of the problem, and progress is also being hampered by onerous post‐approval conditions, including ongoing liability for restorative interventions. Finally, the permitting process stifles innovation and creativity as outcomes are locked‐in at the permit stage. We conclude by highlighting the urgent need to reform legal permitting processes for restoration, as current practice may put the achievement of global restoration targets at risk. It is anticipated that these findings will be of interest to restoration practitioners navigating this space, as well as policymakers.
... Consequently, an interest in recouping lost ecosystem services and/or increasing oyster landings has led to widespread efforts to rebuild reefs (Duarte et al., 2020;Howie & Bishop, 2021;Pogoda et al., 2019). Global reef building efforts have targeted a variety of species including Crassostrea virginica and Ostrea lurida in the US (Bersoza Hernández et al., 2018;Ridlon et al., 2021), Ostrea edulis across Europe (Hughes et al., 2023;Pogoda et al., 2019), Ostrea angasi and Saccostrea glomerata in Australia (Gillies et al., 2018;Pereira et al., 2019), Magallana (Crassostrea) ariakensis and Magallana (Crassostrea) sikamea in China (Quan et al., 2012(Quan et al., , 2017, and Magallana (Crassostrea) hongkongensis in Hong Kong (Fitzsimons et al., 2019). ...
Globally, oyster reef restoration is one of the most widely applied coastal restoration interventions. While reefs are focal points of processes tightly linked to the carbonate system such as shell formation and respiration, how these processes alter reef carbonate chemistry relative to the surrounding seawater is unclear. Moreover, coastal systems are increasingly impacted by coastal acidification, which may affect reef carbonate chemistry. Here, we characterized the growth of multiple constructed reefs as well as summer variations in pH and carbonate chemistry of reef‐influenced seawater (in the middle of reefs) and ambient seawater (at locations ~50 m outside of reefs) to determine how reef chemistry was altered by the reef community and, in turn, impacts resident oysters. High frequency monitoring across three subtidal constructed reefs revealed reductions of daily mean and minimum pH (by 0.05–0.07 and 0.07–0.12 units, respectively) in seawater overlying reefs relative to ambient seawater ( p < .0001). The proportion of pH measurements below 7.5, a threshold shown to negatively impact post‐larval oysters, were 1.8×–5.2× higher in reef seawater relative to ambient seawater. Most reef seawater samples (83%) were reduced in total alkalinity relative to ambient seawater samples, suggesting community calcification was a key driver of modified carbonate chemistry. The net metabolic influence of the reef community resulted in reductions of CaCO 3 saturation state in 78% of discrete samples, and juvenile oysters placed on reefs exhibited slower shell growth ( p < .05) compared to oysters placed outside of reefs. While differences in survival were not detected, reef oysters may benefit from enhanced survival or recruitment at the cost of slowed growth rates. Nevertheless, subtidal restored reef communities modified seawater carbonate chemistry in ways that likely increased oyster vulnerability to acidification, suggesting that carbonate chemistry dynamics warrant consideration when determining site suitability for oyster restoration, particularly under continued climate change.
... Oyster management in Chesapeake Bay and globally emphasizes the twin goals of a healthy ecosystem and a productive wild fishery. One of the critical ingredients of managing reefs for ecosystems and people is quantifying and evaluating oyster reef habitat because of the central role of structurally complex reefs in ecosystem services (Fitzsimons et al. 2019, Smith et al. 2023. It is important to know the type of habitat provided on harvested and restored reefs and understand how the effects of management work in the context of environmental drivers at multiple spatial scales. ...
Oyster reefs provide important services to ecosystems and people, with many of these benefits depending on structurally complex reef habitat. Despite the key role of oyster reef habitat, we have yet to understand natural and anthropogenic drivers of subtidal reef habitat over large spatial scales (>200 km). Chesapeake Bay (USA) offers a valuable system to explore how salinity, restoration, and harvest compare in their influence on subtidal oyster reef habitat because of its broad environmental gradient and mosaic of management types. We applied a remote rapid assessment method using underwater photographs to survey oyster reef habitat in 12 tributaries and scored images based on estimates of oyster percent cover and vertical relief. The broad spatial scale (~215 km) of the survey includes reefs that vary in management status and salinity. Bay-wide habitat scores were higher with greater estimated oyster percent cover and vertical relief on unharvested and restored reefs. Salinity also contributed to Chesapeake Bay-wide patterns, but the relationship depended on harvest status. In assessing the separate management jurisdictions, scores were higher on restored reefs in Maryland and on anthropogenic (i.e. artificially supplemented) reefs in Virginia. A time series over 4 yr in 2 Maryland tributaries showed high and persistent habitat scores in restored sanctuaries, but habitat scores increased for all reefs over time. The results highlight the combined roles of the natural environment and management decisions on oyster reef habitat. The effect of harvest and restoration on habitat underscores the importance of local management decisions in determining the future status of oyster reefs.
... While oyster reef restoration is relatively new in Australia (Gillies et al. 2018), reestablishment of lost oyster reefs and their ecosystem services have been successfully implemented elsewhere over the last four decades (Fitzsimons et al. 2019). Oyster reef restoration on the east coast of the United States has often been implemented at large scales using industrial techniques, however, there have also been many small-scale citizen science initiatives. ...
Oyster gardening is a community‐driven activity where oysters are grown in cages hanging off docks or other coastal infrastructure. Besides the provision of adult oysters for restoration programmes, oyster gardening may also support other ecosystem services such as providing habitat for fishes and invertebrates as well as encouraging community involvement and citizen science. Australia's first oyster gardening programme was undertaken in a canal estate on Bribie Island in Moreton Bay, Queensland between October 2016 and November 2017. Oyster gardens consisting of plastic mesh cages were deployed with either three species of bivalves (polyculture), or exclusively Sydney Rock Oysters (monoculture) to investigate whether the habitat value differed between the two garden types. After one year of growth, polyculture cages supported higher abundances and species richness of both invertebrates and fish compared to the monoculture gardens. Our study showed that oyster gardening can provide habitat for a range of invertebrate and fish species in the highly modified coastal environment of a canal estate. Further studies are needed to discern whether these oyster gardens would also support larger and mobile fauna, such as species with commercial and recreational importance.
This document has been prepared in cooperation with Federal, Indigenous, and State malacologists (mollusk scientists), environmental toxicologists, restoration specialists, and other subject matter experts to provide best practices for freshwater mussel injury determination, early identification of restoration
opportunities, injury quantification and damages determination (also referred to as claim development), and restoration planning, implementation, and monitoring. The experts address the effects of hazardous substance releases and oil spills on freshwater mussels’ complex life histories and essential ecological roles, and offer solutions that will lead to the restoration, recovery, and protection of these organisms that provide important ecosystem services.
Restoration of mussels typically focuses on either subtidal or intertidal habitats, although it is important to consider the full historical range of a species. However, it remains unclear how environmental changes can impact the ability of mussels to survive in tidal heights where they occurred historically. Additionally, there is limited research on the viability of reducing mussel stock size for restoration purposes. In this study, green-lipped mussels Perna canaliculus of 2 size classes (80 and 60 mm) were assessed when transplanted as a single size class or as mixed cohorts in 9 m ² plots at 3 shore heights (i.e. neap low tide, spring low tide, and subtidal). The mussels were sampled over a 1 yr period to understand the effect that shore height and size class had on mussel metrics, such as survival, growth, and condition. The results revealed that shore height had a greater effect than size class on mussel survival, with a total loss of mussels transplanted into areas that were exposed at neap tides in contrast to 39% mussel survival transplanted into areas that were only exposed on spring low tides. Further, mussels transplanted in the adjacent subtidal had higher overall survival (74%). This suggests that aerial exposure time determines the upper vertical limit for restoration by transplantation of mussels sourced from aquaculture, despite their historical distribution. The results of this study also support the use of smaller mussels (~60 mm) for transplantation for mussel reef restoration, as a 25% reduction in size resulted in 50% more mussels being deployed.
1. Ecological restoration includes specific technical phases over the course of an ecosystem recovery process. In the marine environment and for oyster reef restoration, the installation and implementation of pilot reefs close the gap between feasibility studies with small-scale experiments and designated upscaling for marine conservation measures.
2. Against this background, this study presents the design, planning and installation of the first pilot oyster reef in offshore sublittoral regions of the North Sea. The work was conducted as part of marine protected area management in the Natura 2000 site Borkum Reef Ground in the German Bight, in the area of historical offshore oyster grounds.
3. It includes logistical considerations, material selection, methodology for reef base construction and deployment of European flat oysters Ostrea edulis as spat-on-shell, young and adult single seed oysters, and spat-on-reef, as well as the development of an efficient monitoring approach for reef-associated biodiversity.
4. Native Oyster Restoration Alliance monitoring methodologies, such as underwater visual census and seabed images were selected, tested and successfully adapted for the pilot oyster reef and study site. The evaluation and optimization of offshore sublittoral oyster reef monitoring are presented here, and biodiversity metrics are put into perspective with data from recent and historical studies.
5. Results show a few mobile fauna species (e.g., fish and decapods) as first colonizers after reef construction. One year later, biodiversity increased due to a larger number of invertebrate and fish species. However, the pilot oyster reef community still represents an early recolonization stage, with lower biodiversity than historical records.
6. This study presents a proof of concept for the design, planning and construction of an offshore oyster reef and indicates stages in the recovery process. Strategies to optimize and to complement reef-monitoring in challenging environments are discussed, emphasizing additional molecular and functional analyses for future assessments.
Fisheries managers, seafood harvesters, and other commercial fishing stakeholders are increasingly seeking information regarding the regional economic impacts resulting from fisheries management decisions. This project contributes to addressing this need by generating estimates of key economic measures associated with the commercial fishing industry - and connected industries - of the Choptank River System. This project is a Regional Economic Impact Analysis, which accounts for changes in spending and the resulting changes in regional economic activity.
https://spo.nmfs.noaa.gov/content/tech-memo/estimating-ecological-benefits-and-socio-economic-impacts-oyster-reef-restoration
Ecological restoration, when implemented effectively and
sustainably, contributes to protecting biodiversity; improving
human health and wellbeing; increasing food and water security;
delivering goods, services, and economic prosperity; and
supporting climate change mitigation, resilience, and adaptation.
It is a solutions-based approach that engages communities,
scientists, policymakers, and land managers to repair ecological
damage and rebuild a healthier relationship between people
and the rest of nature. When combined with conservation and
sustainable use, ecological restoration is the link needed to
move local, regional, and global environmental conditions
from a state of continued degradation, to one of net positive
improvement. The second edition of the International Principles
and Standards for the Practice of Ecological Restoration
(the Standards) presents a robust framework for restoration
projects to achieve intended goals, while addressing challenges
including effective design and implementation, accounting
for complex ecosystem dynamics (especially in the context of
climate change), and navigating trade-offs associated with land
management priorities and decisions.
Ecological restoration, when implemented effectively and sustainably, contributes to protecting biodiversity; improving human health and wellbeing; increasing food and water security; delivering goods, services, and economic prosperity; and supporting climate change mitigation, resilience, and adaptation. It is a solutions-based approach that engages communities, scientists, policymakers, and land managers to repair ecological damage and rebuild a healthier relationship between people and the rest of nature. When combined with conservation and sustainable use, ecological restoration is the link needed to move local, regional, and global environmental conditions from a state of continued degradation, to one of net positive improvement. The second edition of the International Principles and Standards for the Practice of Ecological Restoration (the Standards) presents a robust framework for restoration projects to achieve intended goals, while addressing challenges including effective design and implementation, accounting for complex ecosystem dynamics (especially in the context of climate change), and navigating trade-offs associated with land management priorities and decisions.
There is a growing body of science to suggest that there is a mutualistic relationship between habitat restoration projects and community volunteers and participation. Restoration projects and programs benefit from community participation via an added labor force and by fostering community investment and support, which is critical for project success and future restoration investments. Community participants gain physically and psychologically rewarding experiences from being a part of restoration projects, while fostering an environmental ethos. Oyster restoration serves as particularly ideal opportunities for engaging community volunteers and participation. These additional values provided to a community where oyster restoration is taking place is an important additive benefit that oyster restoration provides. The nature by which many oyster restoration projects are implemented offers satisfying opportunities for community members to participate in physically rewarding, hands-on work. Many oyster restoration programs are also ideal for incorporating student or citizen science, or broad-scale education and outreach. Despite the growing science to support the value of volunteer and community participation, coupled with increased oyster restoration, there is a paucity of information for project managers to turn-to for guidance as to how community participation can be built into oyster restoration projects and programs. This chapter presents five cases from the United States to demonstrate the broad, and often unique, opportunities to incorporate community and volunteer participation into oyster restoration.
Coastal ecosystem restoration is accelerating globally as a means of enhancing shoreline protection, carbon storage, water quality, fisheries, and biodiversity. Among the most substantial of these efforts have been those focused on re‐establishing oyster reefs across the US Atlantic and Gulf coasts. Despite considerable investment, it is unclear how the scale of and approaches toward oyster restoration have evolved. A synthesis of 1768 projects undertaken since 1964 reveals that oyster substrate restoration efforts have primarily been concentrated in the Chesapeake Bay and the Gulf Coast, have been heavily reliant on oyster shell, and have re‐established 4.5% of the reef area that has been lost across all regions. By comparing costs to ecosystem service benefits, we discovered that the return‐on‐investment of oyster restoration varies widely, but generally increases with project size. To facilitate the recovery of coastal ecosystems and their services, scientists and resource managers must adopt a new restoration paradigm prioritizing investment in sites that maximize economic and ecological benefits and minimize construction costs.
Management actions to protect endangered species and conserve ecosystem function may not always be in precise alignment. Efforts to recover the California Ridgway’s Rail (Rallus obsoletus obsoletus; hereafter, California rail), a federally and state-listed species, and restoration of tidal marsh ecosystems in the San Francisco Bay estuary provide a prime example of habitat restoration that has conflicted with species conservation. On the brink of extinction from habitat loss and degradation, and non-native predators in the 1990s, California rail populations responded positively to introduction of a non-native plant, Atlantic cordgrass (Spartina alterniflora). California rail populations were in substantial decline when the non-native Spartina was initially introduced as part of efforts to recover tidal marshes. Subsequent hybridization with the native Pacific cordgrass (Spartina foliosa) boosted California rail populations by providing greater cover and increased habitat area. The hybrid cordgrass (S. alterniflora × S. foliosa) readily invaded tidal mudflats and channels, and both crowded out native tidal marsh plants and increased sediment accretion in the marsh plain. This resulted in modification of tidal marsh geomorphology, hydrology, productivity, and species composition. Our results show that denser California rail populations occur in invasive Spartina than in native Spartina in San Francisco Bay. Herbicide treatment between 2005 and 2012 removed invasive Spartina from open intertidal mud and preserved foraging habitat for shorebirds. However, removal of invasive Spartina caused substantial decreases in California rail populations. Unknown facets of California rail ecology, undesirable interim stages of tidal marsh restoration, and competing management objectives among stakeholders resulted in management planning for endangered species or ecosystem restoration that favored one goal over the other. We have examined this perceived conflict and propose strategies for moderating harmful effects of restoration while meeting the needs of both endangered species and the imperiled native marsh ecosystem.
As part of an applied research project, an engineering design and structure deployment study was conducted to investigate the feasibility of performing in-situ larval set of Crassostrea virginica within a temporarily deployed containment barrier. The intent of the barrier was to contain free-swimming larvae to maximize set on emplaced shell substrate. The project site was located in the Chesapeake Bay waters of Maryland (USA) in a tidal tributary adjacent to the Patuxent River. The project included a practical ocean engineering approach to specify barrier and mooring system components by investigating environmental design criteria, applying computational fluid dynamic techniques, and characterizing the barrier and mooring leg shape and tension with catenary equations. Following analysis and component specification, both the barrier and mooring system components were deployed. The structure consisted of two, 15 m length sections of Type-III turbidity curtain with a skirt depth of 4.57 meters, but adjustable with furling lines. The structure enclosed an area of about 65 m2 with clean oyster shell substrate and was held vertically in the water column with ∼0.3 meter floats at the surface and chain at the bottom of the skirt. It was deployed with an 8-point spread mooring configuration to maintain its shape in a 0.51 m/s current and 0.75 meter waves. After deployment, larvae were introduced into the enclosed volume and allowed three days to set before removing the barrier. A companion biological field study demonstrated that the technique could add over 180 juvenile oysters/m2 to the site with clean cultch. Recommendations for a potential scaled-up version are also discussed.
Horse mussel (Modiolus modiolus) shellfish reefs are a threatened and declining habitat in the North East Atlantic and support high levels of biodiversity. Shellfish can influence the surrounding water column and modify the quality of material that reaches the seabed by filtering water, actively depositing particles and changing the benthic boundary layer due to surface roughness. In the present study M. modiolus biodeposition was measured in a field location for the first time. The results show that M. modiolus enhance sedimentation and contribute to the downward flux of material to the seabed. Approximately 30% of the total sediment deposition was attributed to active filter feeding and overall, the presence of horse mussels enhanced deposition two fold. The results are discussed in terms of the potential for horse mussel reefs to provide ecosystem services to society, through functions such as benthopelagic coupling and sediment stabilisation. Highlighting the societal benefits supplied by marine habitats can help prioritise conservation efforts and feed into the sustainable management of coastal water bodies.
Victoria has lost vast areas (>95%) of native flat oyster (Ostrea angasi, Sowerby 1871) and blue mussel (Mytilus edulis galloprovinicialis, Lamarck 1819) reefs from estuarine and coastal waters since European settlement. We document the decline of these reefs by examining indigenous use of shellfish, the decimation of oyster reefs by dredge fishing in early colonial days (1840s–1860s) and later removal of mussel reefs by the mussel and scallop dredging industry (1960s‒1990s). Review of current scientific information reveals no notable areas of continuous oyster reef in Victoria and we consider this habitat to be functionally extinct. While the large-scale removal and destructive fishing practices that drove the rapid declines have not occurred since the mid-1990s, a natural recovery has not occurred. Recovery has likely been hampered historically by a host of factors, including water quality and sedimentation, lack of shell substrate for settlement, chemical pollution impacts, disease of native flat oysters (Bonamia), and more recently introduced species that compete with or prey on shellfish. However, research in the United States has demonstrated that, by strategic selection of appropriate sites and provision of suitable settlement substrates, outplanting of aquaculture-reared oysters and mussels can re-establish shellfish reefs. While a long-term sustained and structured approach is required, there is potential to re-establish shellfish reefs as a functioning ecological community in Victoria’s coastal environment.
The eastern oyster (Crassostrea virginica) remains at historically low levels throughout the Chesapeake Bay. Recent efforts to restore oysters in the bay have focused on establishing a series of sanctuaries, or no-take zones, to increase oyster broodstock in selected tributaries. Oyster parasites continue to affect the rate of recovery in these tributaries; however, innovative management strategies, advances in aquaculture technology, and the availability of disease-tolerant broodstock from the lower Chesapeake Bay are providing ways to involve the public directly in restoration of this resource. A 1996 management decision to transplant large wild-caught oysters onto an oyster broodstock sanctuary reef in the Great Wicomico River, Virginia, was followed by greatly increased abundance of juvenile oysters throughout that river in 1997. Using that result as a model for strategic oyster reef restoration, citizens and school students have been enlisted to grow large numbers of hatchery-produced native oysters for restocking other sanctuary reefs throughout Chesapeake Bay. Efforts to supplement natural oyster populations in Hampton Roads, Virginia, began in May 1998, with the transplanting of 65,000 hatchery-produced oysters grown by school students. The oysters were transplanted onto strategically located sanctuary reefs constructed in the Lynnhaven and Elizabeth rivers. Surveys of these reefs following the oysters' spawning season have revealed order-of-magnitude increases in the abundance of juvenile oysters on both reefs, and correspondingly high spat settlement rates on oyster grounds surrounding the reefs. These results demonstrate that stocking strategically located broodstock reefs with hatchery-produced oysters grown by citizens can be an effective strategy for oyster restoration in the Chesapeake Bay.