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The Alabama Cooperative Extension System offers educational programs, materials, and equal opportunity employment
to all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability.
William C. Walton*1,2, Julie E. Davis2, Glen I. Chaplin2, F. Scott Rikard2, Terrill R. Hanson1,2, P.J. Waters1,2,3 & D. LaDon Swann2,3
1Alabama Cooperative Extension System, 2Auburn University, 3Mississippi-Alabama Sea Grant Consortium
*Assistant Professor and Marine Fisheries Extension Specialist
July 2012
Off-bottom oyster farming is the culture of oysters
in some type of mesh container (basket, bag, cage,
etc.) that is held above the seafloor. Oysters grown
this way are typically hatchery-reared single set
oysters instead of clumps of oysters normally
found in the wild. The container provides
protection from predators and eliminates burial in
sediment. Suspending oysters in the water column
improves growth rates due to improved water
flow. Off-bottom production systems take
advantage of the availability of food (single cell
algae called phytoplankton) throughout the water
column and have the following potential
advantages over other production methods like bottom culture:
Promote faster growth;
Increase survival;
Allow control of fouling (e.g., barnacles, overset oysters, mud worms);
Improve shell shape and appearance; and
Increase product consistency.
Agriculture & Natural Resources
Figure 1. Off-bottom oyster farm in Mississippi Sound with three types of
production gear.
Timely Information: Off-Bottom Oyster Farming 2
Oysters produced using off-bottom culture
techniques are typically sold to the premium half-
shell market. Traditional on-bottom production
(from either public oyster reefs or private oyster
grounds) yields very large quantities of oysters that
tend to obtain lower prices than farm-raised oysters.
For example, the 5-year average price of Gulf Coast
oysters (from 2006-2010) was $3.17/pound (in
shell) versus the same 5-year average price of New
England oysters of $33.67/pound (National Marine
Fisheries Service). Gulf Coast oysters harvested
from the bottom are primarily intended for the
shucked meat market and can vary widely in quality
and condition. Only the best of these oysters are selected for the premium half-shell market, where oysters are
sold live in their shells to be eaten raw. These oysters are still variable enough that they are consistently valued
for much less than farm-raised oysters from the other regions of the United States.
Opportunity for the Gulf Coast
There are well-developed markets for premium farm-raised oysters elsewhere in the nation, with strong oyster
farming industries established in other regions. There are several possible reasons why oyster farming has not
become established along the Gulf Coast.
1. The very productive waters of the Gulf of Mexico pose a technical challenge. While allowing for very
rapid oyster growth, these waters also lead to very rapid fouling of the production gear by algae,
barnacles, and other fouling animals. The fouling can significantly reduce water flow and food supply to
the oysters if not regularly cleaned. Previous attempts to farm oysters off-bottom in the Gulf of Mexico
region required substantial labor costs associated with fouling control.
2. The condition of oysters decreases during the spawning season. When oysters spawn, the meats become
thin and watery. As a result, the marketability of oysters is reduced during spawning season.
3. Lack of branding oysters from the Gulf Coast makes it difficult to enter the highly competitive premium
half-shell market. Beyond the famous Apalachicola oyster, almost all other oysters harvested from the
Gulf of Mexico are labeled and sold as ‘Gulf oysters’.
Figure 2. Premium Gulf Coast off-bottom cultured oysters.
Timely Information: Off-Bottom Oyster Farming 3
Auburn University, Alabama Cooperative Extension System, Louisiana State University, Mississippi-Alabama
Sea Grant Consortium, Louisiana Sea Grant and National Sea Grant, and private farmers have partnered since
2009 to address the barriers to oyster farming. Removing the barriers will lead to the development of a new
oyster industry that will create jobs and provide a more reliable supply of oysters in Alabama, Mississippi,
Louisiana and other Gulf of Mexico States. The results of this research, Extension and industry partnership
include the following.
1. Several production methods have been
developed that allow for relatively easy control
of fouling by allowing controlled exposure to
air (forcing a simulated extended ‘low tide’) for
various durations and frequencies. Efforts by
pilot commercial operations have demonstrated
substantial market demand for branded, farm-
raised Gulf Coast oysters at a price competitive
with oysters farmed in other regions of the US.
Though a niche market, there has been demand
created throughout the southeastern US and
other regions in this specialty crop.
2. Experiments with triploid oysters have allowed
the production of non-reproductive oysters with good summer condition. Alternatively, oyster farmers can
simply choose to conduct seasonal harvests when condition is optimal.
3. Experiments with triploid oysters have allowed the production of non-reproductive oysters with good
summer condition. Alternatively, oyster farmers can simply choose to conduct seasonal harvests when
condition is optimal.
While challenges to off-bottom oyster farming in the Gulf of Mexico remain, research suggests that oyster
farming may be a viable near-shore domestic aquaculture industry that can provide an economic benefit to
coastal communities. Both producers and related supporting industries will benefit from development of this
industry. Considerable interest exists for off-bottom oyster farming within the Gulf region. This fact sheet
summarizes some challenges and considerations for prospective off-bottom oyster farmers: location, choice of
production gear, permitting, security, coastal storm preparedness, business planning and marketing.
Figure 3. Adjustable longline production culture system, with baskets on
the right set at standard depth and baskets on the left raised to increase
the duration of exposure in order to control fouling.
Timely Information: Off-Bottom Oyster Farming 4
Challenges and Considerations
In Alabama, prospective farmers are required to obtain the use of private oyster riparian rights, either through
purchase of waterfront property where oyster riparian rights can be successfully exerted or through a lease of
already obtained oyster riparian rights from another waterfront property owner. Oyster riparian rights allow a
waterfront landowner to determine who may harvest in a designated area up to 1,800 feet offshore from the
mean low tide line (subject to restrictions). The use of oyster riparian rights has been encouraged as a
mechanism for off-bottom oyster farms by state regulatory agencies. The State Lands Division of the Alabama
Department of Conservation and Natural Resources requires a minimum 10’ upland buffer be leased (along
with any oyster riparian rights) to provide an ‘upland interest’ to the lessee.
Of course, there are many other factors that
should be considered in selecting a location for an
off-bottom oyster farm. Most importantly, any
oyster farm where oysters are harvested for
market must be within waters that are, at a
minimum, classified as “conditionally approved”
for harvest by the Alabama Department of Public
Health. Furthermore, it is unlikely that permits
will be obtained in areas where submerged aquatic
vegetation (sea grasses) is present. An ideal
location should also provide conditions for rapid
oyster growth (e.g., salinities typically above 15
parts per thousand, or ppt) and high survival.
These two requirements can be assessed before final site selection, but sporadic events also need to be
considered (e.g., prolonged freshwater, low dissolved oxygen).
Beyond these critical elements in site selection, logistical considerations should be taken into account, including
protection from prevailing weather, travel distance, conflicts with other users, etc. In addition, the bottom type
(e.g., sand, mud) and the water depth should be considered because these will affect the choice of production
Figure 4. Bill Walton, Extension Specialist, has assisted prospective
farmers with site selection by assessing oyster growth and survival at
potential sites. Photograph by Katie Jackson.
Timely Information: Off-Bottom Oyster Farming 5
Choice of Production Gear
The choice of production gear should be based on a combination of
factors including investment and operating costs, profitability,
desired farm layout, availability of equipment and replacement
parts, ease of handling, durability and likelihood of surviving
severe weather. Importantly, in waters along the Gulf Coast, gear
that readily allows for the control of fouling by periodic air drying
(also called emersion) is highly recommended. Fouling has the
potential to overwhelm an oyster farmer who would incur very high
labor costs to control the fouling organisms. Pro-active control of
fouling is essential, with routine control measures taken before
fouling becomes problematic. Regular monitoring of the oysters
and gear is recommended to identify when additional fouling
control should be carried out. Additionally, gear choice should be
based on realistic expectations of available labor. For example,
some gear is best handled by at least two individuals.
Obtaining the proper permits is essential to establishing an oyster farm. Permitting is specific to each state and
subject to change. Local permitting agencies should be approached about current permitting requirements and
guidelines. In Alabama, permitting agencies involved with off-bottom oyster farming include the Marine
Resources Division (MRD) of the Alabama Department of Conservation and Natural Resources (ADCNR), the
Alabama Department of Public Health (ADPH), the Alabama Department of Environmental Management
(ADEM), State Lands Division of ADCNR, and the US Army Corps of Engineers (USACE). Additional
agencies likely will be involved in the application process (e.g., Alabama Marine Police, US Fish & Wildlife
Service, etc.). These permits are for varying durations which should be considered when planning the scope of
each permit.
Figure 5. It is highly recommended that any culture
gear selected readily allow control of fouling by periodic
air drying. These floating cages, for example, can be
flipped up on the floats periodically to expose the gear
and oysters to the air.
Timely Information: Off-Bottom Oyster Farming 6
As of this writing, establishment of an off-bottom oyster farm requires the following from an applicant:
Establish legal control of oyster riparian rights (established per MRD regulations that require a certified
survey of the bounds);
Submit a joint application to the USACE and ADEM (with an associated fee). This is then subject to
public comment and review by ADEM for consistency with the Coastal Management Plan. The
application likely will be reviewed by other state and federal agencies;
Provide a survey of submerged aquatic vegetation (SAV) during the growing season (June through
September) as required by ADEM; and
Submit Riparian Easement application to the State Lands Division of ADCNR for commercial activity
that exempts other public uses of the state-owned sea bottom. This easement will incur an annual charge
of approximately $0.15 per square foot of exempted area.
After these permits are obtained, construction may proceed with periodic renewal of the permits.
To begin operation of an off-bottom oyster farm the following is required:
Submit an operations plan to ADPH describing the farm’s facilities and operations. This is required to
obtain an aquaculture permit which is renewed annually;
Obtain an annual oyster harvester’s permit and harvest tags from MRD; and
Submit a list of people involved in working the oyster farm to MRD. Update this list frequently as
workers are added or removed. Workers will need to carry dated written permission (issued at least
monthly) to be working on the oyster farm.
Those interested in beginning an oyster farm are encouraged to check with permitting agencies for current
regulations and requirements.
Oyster farming requires an investment of time and money. Theft and vandalism could lead to significant losses
of oysters and gear. By exerting oyster riparian rights, the boundaries of oyster farms are enforced by MRD.
Additional measures may be advisable, including security cameras or some sort of regular watch. Where oyster
Timely Information: Off-Bottom Oyster Farming 7
farms are located near other oyster farms or coastal businesses, there may be opportunities for business owners
to assist each other with security.
Coastal Storm Preparedness
Any oyster farmer along the Gulf Coast must have a severe
storms preparedness plan. The implementation of the plan
should be triggered by specific levels of storm warning. Given
the limited time for preparation and the difficulty in keeping
oysters alive for lengthy durations out of the water with likely
power outages, removing oysters and gear from the water is not
a practical solution. Therefore, it is recommended that oysters
and gear be well secured at or near the sea bottom prior to a
storm’s arrival. For example, floating cages can be sunk and
longline baskets moved to the lowest clip position on support
poles. All lines and anchors should be inspected for chaffing or
other damage and reinforced where needed prior to any storm
event. As soon as practical after a storm event, the farm site
should be inspected for damage and gear returned to normal
operating condition. Significant effort should be made to locate
and remove any debris originating from the oyster farm.
Business Planning
It is strongly advised that anyone considering oyster farming put together a thorough business plan before
investing significant time or money. AgPlan is one on-line, free, business plan development site that can help
( Business planning allows:
Establishing markets;
Careful consideration and comparison of various options (e.g., location, gear);
Understanding of upfront and ongoing costs and the range of potential profits;
Identifying risks and opportunities; and
Obtaining loans or securing investment.
Figure 6. Advisor Glen Chaplin periodically inspects
lines for chaffing at the Auburn University research
Timely Information: Off-Bottom Oyster Farming 8
It is recommended that oyster farmers carefully track their costs, production and sales over time. A number of
specialized software packages exist for this purpose. These records will also be useful for potential expansion
and accounting purposes.
Oyster harvesters must sell their product to a properly licensed
wholesaler; direct sales by harvesters are prohibited. Oyster
harvesters, however, may choose to become wholesalers as well.
Farmers should contact the ADPH for current options and
requirements (with extra requirements for those wishing to ship
interstate). Harvest is currently regulated the same way as wild
harvest using the volume of oysters contained in a sack. Oyster
farmers will likely want to sell by the piece (e.g., 200 oysters per
sack). Note that each sack will require a harvest tag with
appropriate records kept of harvest (temperature, salinity, etc.),
transport and sales.
Additionally, those interested in off-bottom oyster farming should recognize that current business models
indicate that the primary market is the premium, half-shell market where oysters are sold live in their shells.
This is a specialized, niche market and oyster farmers need to be aware that many oyster dealers may not have
buyer accounts for this product form. Though not able to sell directly (unless specifically licensed), oyster
farmers may want to encourage sales by speaking directly with restaurants and fish markets about their product.
In other parts of the country, branding of oysters by location or farm name has worked well. These brands, or
appellations, are like wines or specialized beers (micro-brews), and seem to appeal to a niche audience that is
often willing to pay more for the product. Still, any oyster farmer on the Gulf Coast should recognize that this is
a developing market in the southeastern U.S.
Figure 7. Branding of oysters cultured in off-bottom
oyster farms has been a very successful marketing
... Different approaches are employed to address these challenges in the studied markets. As noted above, leasing regulations vary by state, but as one example in the Gulf of Mexico of the US (Alabama), prospective farmers obtain oyster riparian rights either through waterfront property ownership or leasing from other waterfront property owners, ensuring control over designated harvesting areas [67]. In Sweden, fishing laws regulate ownership of natural oyster stocks, with oysters belonging to land/water owners up to 200 m from the shore [52], yet harvest is only allowed in designated production areas for food safety reasons. ...
Full-text available
In the face of an increasing world population and a subsequent need for an increase in sustainable and healthy food production, low trophic species, such as oysters, emerge as a promising alternative. However, regional variations in oyster production techniques, market dynamics, and consumption patterns create challenges for both the global and local industry’s growth. In this study, a descriptive qualitative analysis of oyster markets across seven Atlantic regions was carried out. The Pacific oyster (Crassostrea gigas) was found to be farmed in most Atlantic regions except the US but is classified as invasive in Sweden and potentially invasive in South Africa. Other farmed and/or harvested species include native species (C. gasar and C. rhizophorae) in Brazil, the American cupped oyster (C. virginica) in the US, and the European flat oyster (Ostrea edulis) in France, Sweden, and the US. In Irish farms, Pacific oysters are primarily for export to European markets. The marine aquaculture sectors of Sweden, South Africa, and Namibia, as well as Brazil’s farming for C. gasar, were found to be underdeveloped. This study also observed a variation in licensing, property rights, and regulatory frameworks. Financial challenges for small businesses, ecological implications of seed production techniques, biosecurity risks, and public health considerations are emphasized as critical areas for attention. This study offers valuable insights into the selected markets and can serve as a useful resource for policymakers, aquaculture practitioners, and stakeholders in optimizing global shellfish industry strategies.
... However, off-bottom culture is becoming increasingly popular due to regulatory constraints and market trends. This method can result in a higher-quality product for the half-shell market (Walton et al. 2012) and has also been shown to reduce some impacts to eelgrass, as disturbance due to mechanical harvesting is reduced (Tallis et al. 2009, Ferriss et al. 2019. The ecological impacts of such practices, where cages, floats, rafts, lines, and supporting structures are also placed in the estuary, are less well-understood. ...
Full-text available
Estuaries are subject to diverse anthropogenic stressors, such as shellfish aquaculture, which involve extensive use of estuarine tidelands. Pacific oyster Crassostrea gigas aquaculture is a century-old practice in US West Coast estuaries that contributes significantly to the regional culture and economy. Native eelgrass Zostera marina also commonly occurs in intertidal areas where oyster aquaculture is practiced. Eelgrass is federally protected in the USA as ‘essential fish habitat’, restricting aquaculture activities within or near eelgrass. To contribute scientific information useful for management decisions, we sought to compare fish habitat use of oyster aquaculture and eelgrass, as well as the edges between these 2 habitats, in Willapa Bay, Washington, USA. Furthermore, given a recent shift towards off-bottom culture methods, in part to protect seagrasses, long-line and on-bottom oyster aquaculture habitats were compared. A combination of direct (underwater video, minnow traps) and indirect (predation tethering units, eelgrass surveys) methods were employed to characterize differences in fish habitat use. Eelgrass density declined within both aquaculture habitats but less so within long-line aquaculture. Most fish species in our study used long-line oyster aquaculture and eelgrass habitats similarly with minimal edge effects, and on-bottom aquaculture was used less than either of the other 2 habitat types. These results are consistent with previously observed positive relationships between fish abundance and vertical habitat structure, but also reveal species-specific behavior; larger mesopredators like Pacific staghorn sculpins were sighted more often in aquaculture than in interior eelgrass habitats.
Growth of the oyster aquaculture industry on the US east coast has accelerated in recent decades due to advances in breeding technologies and grow-out methods. As the industry grows, competition in the market place is likely to increase attention to product quality, for example, shell conformation and meat content. This study investigated how gear type and tidal zone location influenced shell shape and product quality of Crassostrea virginica during a four month “finishing” period at an oyster farm on Fishing Creek MD on the eastern shore of Chesapeake Bay. For these experiments, a mix of sub-market sized, triploid oysters from two local farms were deployed in four gear treatments that varied in water column location and exposure to wave action: OysterGro™ floats, a rack and bag system, a bottom cage placed in the intertidal, and a bottom cage placed subtidally, which represents the ‘control’ treatment (no change of gear type for finishing). Shell height, length, width, and weight (total and wet meat) were measured each month from August to December 2015 and an index of shell shape relative to an idealized 3-2-1 ratio of height to length to width was calculated. Overall, oysters grew well in all gear types (3.0–-4.8 mm increase in shell height per month) and experienced relatively low mortality (4–8% across treatments) – mean height of oysters from each gear treatment exceeded market size by the end of the experiment. Gear treatment had a significant effect on oyster height and weight at the end of the experiment (P < 2.0e–05) and the OysterGro™ treatment produced the largest gains in growth compared to all other treatments (2.3-2.5 fold– increase in wet or total weight). Gear type also affected shell shape (P = 0.023), with significantly lower mean 3-2-1 ratio deviations (more ideal, rounded shells) in the OysterGro™ compared to subtidal bottom cage or rack and bag gear. Shell shape improved the most between initial and final time points for the OysterGro™ treatment, while the rack and bag and bottom cage subtidal treatments showed no improvement. This study provides some of the first data on growth performance and shell shape using the OysterGro™ system in Chesapeake Bay and overall, results indicate that floating gear such as the OysterGro™ system may be a valuable method to finish oysters, facilitating good growth, and improving shape over a relatively short period of time.
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