European Oyster (farmed)

Ostrea edulis

Sometimes known as European Flat Oyster.

This species is farm-raised.

Criterion	Points
Inherent Operational Risks	2.50
Feed	3.75
Pollution	4.00
Risk to Other Species	2.25
Ecological Effects	2.25
Final Score (average of criteria)	2.95
Color

Final Score	Color
2.60 - 4.00
2.20 - 2.59
1.80 - 2.19
1.40 - 1.79
0.00 - 1.39

Last updated January 9, 2006.

Inherent Operational Risks

Core Points (only one selection allowed)

General System Design:

An aquaculture system's design is a good overall proxy measure for the likely effect of the operation on the environment. For example, open systems (e.g., net pens and net cages) are more likely to have pollution, disease, and escape issues than closed systems (e.g., recirculating tanks). With shellfish, which don’t require supplemental food input, the more important question is whether they are harvested on or off of the bottom.

1.00

This species is raised in a high risk system (e.g., net pens; net cages).

2.00

This species is raised in a moderate risk system (e.g., most ponds; raceways; bottom culture of mollusks).

Most of the oyster production in the United States comes from American and Pacific Oysters. However, the U.N. Food and Agriculture Organization (FAO) reports that 36 mt of farmed European Oysters were produced in the U.S. in 2002 (FAO Stats 2002). European Oysters are farmed primarily in Maine and Washington (NMFS 2004). These oysters are generally cultivated both on bottom and in suspension systems. For the first growing season, the oysters are raised in floating trays; the following season they are held in lantern nets that are suspended from surface longlines, and in the last year, they are placed on the bottom to improve their shape (Matthiessen 2001).

There are no reported imports of any oyster species from any European country (NMFS 2004). Populations of European Oysters in Europe have been devastated in recent years due to overfishing, pollution and disease (Matthiessen 2001). NMFS (2004) reports significant imports of unspecified oysters from Canada. European Oysters are cultivated there, so we assume that some make it into the U.S. market, and therefore consider Canada in this evaluation.

3.00

This species is raised in a low risk system (e.g., re-circulating closed system; suspended culture of mollusks; zero-discharge ponds).

Points of Adjustment (multiple selections allowed)

-0.25	Species is raised at a high stocking density; OR there is a high density of sites in the geographic region, with evidence of environmental impact.
-0.25	Operations do not incorporate best-available, cost-effective technology to reduce environmental impact.
-0.25	There are no effective zoning or permitting practices for siting of facilities.
-0.25	Government programs encourage expansion of high-impact systems.

+0.25	Species is raised at a low stocking density OR there is a low density of sites in the geographic region, which results in minimal impact to the natural ecosystem. Oysters are not grown at high densities, and there are relatively small numbers of sites in Maine and Washington (Matthiessen 2001).
+0.25	Operations incorporate innovative culture methods that limit environmental impacts (e.g., polyculture).
+0.25	There are effective zoning or permitting practices for siting and operation of facilities (e.g., mandatory consideration of hydrographic characteristics; requirements for site rotation). In Washington, most tidelands are privately owned, but aquatic farms must be registered through the Department of Fish and Wildlife. All states’ shellfish farms are certified through a registered Shellfish Authority, which is usually the state's department of health or agriculture. Depending upon culture operations, shellfish farms may require various shoreline development or use permits through local county ordinances. Most shellfish aquaculture activities are permitted through the Army Corps of Engineers Nation Wide Permit 4 (Downey 2004). In Maine, the Department of Marine Resources grants aquaculture leases for up to 10 years and up to 200 acres per lease. Lease proposals are subject to an adjudicatory hearing, which considers the impact of an aquaculture operation on navigation, fishing, access for riparian owners and coastal zoning statutes. Some environmental impacts that are taken into consideration are: displacement of rooted or attached marine vegetation, alteration of current flow, increased rates of sedimentation or sediment resuspension and disruption of fish migration (Maine DMR 2003). In Canada, the provinces and territories are responsible for the majority of site approvals and for overseeing the industry’s day-to-day operations. The federal role involves such areas as research, technology transfer, training and development, access to financing and environmental sustainability relating to the industry. Federal regulations are applied by a number of departments, including Fisheries and Oceans Canada (DFO), Agriculture and Agri-Food Canada, Environment Canada, Health Canada, and by bodies such as the Pest Management Regulatory Agency, the Canadian Food Inspection Agency and others (DFO 2004). The regulations require that sites undergo environmental assessments, under the Canadian Environmental Assessment Act (CEAA), are accessed for the possibility of a harmful alteration, disruption or destruction (HADD) of fish habitat under section 35 of the Fisheries Act, or interfere with native rights and land claims, migratory birds, utilization by other groups, and shellfish food safety (DFO 2004). Both U.S. and Canadian permitting practices thoroughly consider adverse effects of siting.
+0.25	Government programs preferentially encourage the expansion of low-impact systems over high impact systems.

2.50	Points for Inherent Operational Risks

Feed

Core Points (only one selection allowed)

Ecological Footprint of Feed:

"Trash" fish, frequently used in developing countries, is an industry term used to refer to whole fish or fish parts fed to farmed fish without being processed into fish meal and fish oil.

Twenty percent was selected as a cut-off because carnivorous species (e.g., salmon; eel; tuna; cobia; etc.) generally consume greater than twenty percent fish products (fishmeal, fish oil, or trash fish), while omnivorous or herbivorous species (e.g., catfish; tilapia; carps; etc.) consume less than twenty percent fish products.

1.00	Typical aquaculture feed includes high levels of fishmeal, fish oil, or "trash" fish (i.e., >20% of the feed; e.g., salmonid feeds).
2.00	Typical aquaculture feed includes moderate levels of fishmeal, fish oil, or "trash" fish (i.e., <20% of the feed; e.g., tilapia and catfish feeds).
3.00	No feed is used (e.g., mollusks and seaweeds) or typical aquaculture feed includes no fishmeal, fish oil, or "trash" fish (e.g., paddlefish; filter-feeding carps). No feed is used to farm European Oysters, as they are filterfeeders and get their nutrients directly from the surrounding water (Matthiessen 2001).

Points of Adjustment (multiple selections allowed)

-0.25	When fish products are used, the major sources score low on the Wild-Caught Fisheries Ranking System.
-0.25	Feed contains greater than 10% of fish products and public or private sectors are not working to reduce fish content in feed.
-0.25	Feed conversion ratio (FCR) is high (i.e., >2.0; e.g., eel).
-0.25	Government policy promotes research, development and commercialization of carnivorous or other highly fishmeal-dependent species.

+0.25	When fish products are used, the major sources score high on the Wild-Caught Fisheries Ranking System; OR the source is innovative and ecologically sound (e.g., fisheries byproducts); OR no feed is used. No feed is used (Matthiessen 2001).
+0.25	Feed contains less than 10% of fish products OR public and private sectors are working to reduce the fish content in feed; OR no feed is used. No feed is used (Matthiessen 2001).
+0.25	Feed conversion ratio (FCR) is low (i.e., <1.3; e.g., salmon); OR no feed is used. No feed is used (Matthiessen 2001).
+0.25	Government policy promotes research, development and commercialization of herbivorous species or other species not highly dependent on fishmeal.

3.75	Points for Feed

Pollution

Core Points (only one selection allowed)

Typical effluent treatment procedures:

1.00	Effluent is not treated before discharge (e.g., salmon net pens).
2.00	Effluent is partially treated before discharge (e.g., infrequently discharged effluent from catfish ponds).
3.00	Effluent is substantially treated before discharge (e.g., recirculating shrimp systems; settling ponds; reconstructed wetlands); OR treatment is not necessary because supplemental feed is not used (e.g., molluscs or seaweeds). Treatment of effluent is not necessary because supplemental feed is not used to farm European Oysters.

Points of Adjustment (multiple selections allowed)

-0.25	Operations have demonstrated negative impacts on water quality or sediment/benthic characteristics (e.g., elevated nutrient levels; algal blooms; altered benthic communities).
-0.25	Pollutants (e.g., pesticides; parasiticides; antibiotics; plastic; nets; dead fish) are frequently discharged into the environment or otherwise not appropriately discarded.
-0.25	Effluent regulations do not exist, are lax, or are poorly enforced, which allows for degradation of the aquatic environment.
-0.25	Available technologies and practices to reduce or recycle waste (e.g., feed sensors; low-pollution feeds) are not used.

+0.25	Operations generally improve water quality or sediment/benthic characteristics (e.g., oyster farms). Oysters improve water quality by filtering out algae and other plankton, reducing levels of nitrogen, phosphorous and other nutrients (Downey, pers. comm. 2004).
+0.25	Chemicals (e.g., pesticides; parasiticides; antibiotics) are rarely or never used. Chemicals are not used.
+0.25	Robust water quality regulations exist (e.g., permits required; discharge caps; strong enforcement), and regular monitoring occurs. In general, no controls are necessary for effluent from European Oyster operations, as the oysters are biofilters, contributing to control of excess nutrients in the water column. However, water quality is monitored by the National Shellfish Sanitation Program, and in the event of contamination from harmful algal blooms (such as red tides), or bacteria, growing areas are closed to harvest to protect public health (Downey 2004).
+0.25	Innovative methods and practices to reduce or recycle wastes are used (e.g., integrated systems; effluent and solid wastes used as terrestrial fertilizer); OR innovative methods and practices are not needed because raising this species does not create waste. Farming this species does not create waste.

4.00	Points for Pollution

Risk to Other Species

Core Points (only one selection allowed)

Frequency and Impact of Escapes:

1.00	Farmed species regularly or intermittently escape into the wild AND escapes are non-native to the area or otherwise pose a risk to native populations or ecosystems (e.g., most non-native fish raised in outdoor facilities).
2.00	Escape frequency is not known OR farmed species is native to the area where it is raised and poses minimal risk to native populations or ecosystems (e.g., channel catfish in the US; most native mollusks). The European Oyster's native range is in the Mediterranean Sea and along the coasts of Western Europe and the United Kingdom (Matthiessen 2001). They were introduced in the U.S. in the 1950s. The oysters only survive in limited areas, because they are highly sensitive to salinity and temperature, and they do not seem to be causing ecological damage (Glidden Point 2004; Sea Grant 2004).
3.00	Farmed species never (or virtually never) escape to the wild (e.g., species is raised in bio-secure facilities).

Points of Adjustment (multiple selections allowed)

-0.25	This farmed species has been known to survive in the surrounding ecosystem if it escapes; OR would likely survive given its physiological requirements. European Oysters are farmed in the open water, so "escape" is common. In some cases, farmed European Oysters do not spawn, or their offspring do not survive, in the surrounding ecosytem (Glidden Point Sea Farm 2004).
-0.25	This farmed species is known or is likely to compete with wild species for food or habitat if it escapes; OR this species is known or is likely to compromise the genetic integrity of the wild species (e.g., through spawning disruption, genetic introgression or establishment of feral stocks) if it escapes.
-0.25	This farmed species is known or is likely to amplify and transmit disease or parasites to wild populations (e.g., infectious salmon anemia or sea lice infestations) if it escapes.
-0.25	Regulatory authorities are not adequately addressing the risks of escape or spread of disease associated with farming this species.

+0.25	This farmed species has not been known to survive in the surrounding ecosystem if it escapes; OR would not likely survive given its physiological requirements; OR farmed species is a native mollusc.
+0.25	Operations employ management protocols and techniques to limit the ecological impacts of escaped farmed fish (e.g., triploidy; sterilization); OR it’s unlikely that escaped individuals will either compete with wild species for resources, or compromise the genetic integrity of wild species. It is unlikely that escaped individuals will compete with wild species for resources or compromise the genetic integrity of wild species, because native oyster populations, especially on the East Coast, have suffered severe declines, and farmed oysters may help to fill an ecosytem role that is missing.
+0.25	Operations employ effective disease and parasite management protocols (e.g., fallowing of pens; retaining water when disease outbreak occurs); OR incidence of disease or risk of retransmitting disease is low.
+0.25	Regulatory authorities are addressing the risks of escape and spread of disease associated with farming this species. In the U.S., states' departments of health or agriculture oversee the transfer of shellfish between states under The National Shellfish Sanitation Program (NSSP) (Kraeuter and Castagna 2001). States' departments of fish and wildlife or fish and game oversee the transfer of live animals intended for replanting (such as planting out seed from hathceries to growing areas). A high health program, developed by the Pacific Shellfish Institute, provides stringent guidelines for hatcheries to assure disease-free seed is supplied to industry for grow-out (Downey, pers. comm. 2004).

2.25	Points for Risk to Other Species

Ecological Effects

Core Points (only one selection allowed)

Ecological sensitivity of site used for operations:

1.00	Operations are generally located in areas of high ecological sensitivity (e.g., coastal wetlands; mangroves).
2.00	Operations are generally located in areas of moderate ecological sensitivity (e.g., coastal and nearshore waters; rocky intertidal or subtidal zones; river or stream shorelines). European Oysters are generally raised in intertidal and subtidal zones.
3.00	Operations are generally located in areas of low ecological sensitivity (e.g., land that is less susceptible to degradation such as land formerly used for agriculture or land previously developed).

Points of Adjustment (multiple selections allowed)

-0.25	Farming this species causes substantial damage to surrounding habitat, ecosystem or other resources (e.g., groundwater depletion; stream diversion; saltwater intrusion; soil salinization; loss of habitat for juvenile fish; loss of flood control; dredging hard bottoms; etc.).
-0.25	Harmful or lethal predator deterrents are used (e.g., bird/seal shootings; acoustic deterrent devices); OR operation otherwise harms wildlife (e.g., dolphin/seal entanglement; disrupting migration routes; bird/animal shooting).
-0.25	If seed is collected from wild sources, the intensity of collection is high enough to result in depletion of brood stock, wild juveniles, or associated non-target organisms (e.g., collection of postlarvae shrimp).
-0.25	Government policy encourages aquaculture operations to locate or expand in areas of high ecological sensitivity.

+0.25	Operations enhance habitat structure or function (e.g., constructed wetlands). Oysters improve water quality by filtering out algae and other plankton, reducing levels of nitrogen, phosphorous and other nutrients (Downey, pers. comm. 2004).
+0.25	Predator deterrents are not used OR predator deterrents are used but are not harmful or lethal (e.g., predator exclusion nets), AND operation does not otherwise harm wildlife.
+0.25	Seed comes predominantly from hatcheries or on-farm sites (e.g., seed for trout); OR if seed is collected from the wild, it does not deplete brood stock, wild juveniles, or associated non-target organisms (e.g., collection of oyster or mussel spat).
+0.25	Government policy encourages the growth of aquaculture operations in areas of low ecological sensitivity; OR protects sensitive habitats from aquaculture operations (e.g., prohibitions on cutting mangroves).

2.25	Points for Ecological Effects

References

FAO Statistics. 2002. Aquaculture Production through 2002 and Capture Procution through 2002. Fisheries Department, Fishery Information. Data and Statistics Unit.

Department of Fisheries and Oceans Canada (DFO). 2004. Office of the Commissioner for Aquaculture Development. Regulation and Support for Aquaculture in Canada. Available online at: http://ocad-bcda.gc.ca/eregulationandsupport.html. Accessed 24 June 2004.

Downey, R., Executive Director, Pacific Coast Shellfish Growers Association. Personal Communication. 18 May 2004, and 27 September 2004.

Glidden Point Sea Farm. Available online at: http://www.oysterfarm.com. Accessed 28 September 2004.

Kraeuter, J.N. and M. Castagna, Eds. Biology of the Hard Clam. Developments in Aquaculture and Fisheries Science – 31. Elsevier. Amsterdam, The Netherlands.

Maine Department of Marine Resources. 2003. Chapter 2: Aquaculture Lease Regulations. Available online at: http://www.maine.gov/dmr/aquaculture/Chapter02.pdf. Accessed 29 July 2004.

Matthiessen, George C. Oyster Culture. Fishing News Books, Blackwell Science Ltd. Great Britain. 2001.

National Marine Fisheries Service. Fisheries Statistics & Economics Division. Trade Data. Available online at: http://www.st.nmfs.gov/st1/index.html. Accessed 23 September 2004.

Sea Grant. Marine Bioinvasions Fact Sheet: New England Marine Bioinvaders. Available online at: http://massbay.mit.edu/resources/pdf/case-studies.pdf. Accessed 28 September 2004.