Quahog Grow-out - Applied Shellfish Farming

Quahog Grow-out (Plus a few other clams)

Dale Leavitt

Quahog Environment

Growing Quahogs

• Obligate infaunal clam • What does that mean?

• Needs to be in sediment at some point in their life.

• Usually planted sometime after they get to 8 mm (1/3 inch) • Normally can rear up to 15 mm (>1/2 inch) over the first summer

(in nursery)

• Have been planted under growout nets as small as 3 mm (1/8 inch)

• If held out of sediment much beyond 20 mm (3/4 inch) then get • Deformed shells

• Increased mortality

• Need to be protected through much of their life • Size refuge at 35-40 mm (1.5 inch)

What technology should I use?

• Dependent on location and species

• Categorize according to location in environment

• In Bottom

• On Bottom

• Suspended

• Floating

• Only real decisions

• Intertidal

• Shallow subtidal

Quahog & other infaunal clams

In Bottom

Process

• Define planting bed

• Prepare bed

• Plant seed

• Cover

• Maintain

• Harvest

Cover Netting

Netting IN

TE

RN

ET

Define planting bed

• Bed size dependent on multiple factors • Covering material

• Mostly 14’ wide with farmer defined lengths

• Number of seed that you are planting

• Target: 50-100 clams/ft2

• Start at low density and build up

• Can plant smaller seed at higher density (500 clams/ft2) if plan to thin out after first year.

• Example • Wish to plant 100,000 seed at 75/ft2

• 100,000/75/ft2 = 1,333 ft2 required

• 1,333/12 = 111 ft of mesh or ~ 100 foot net

Mark out plot

Bed Preparation

Another option?

Hydraulic Option

Plant the seed

Seed Prices

75 clams/ft2

Covering the crop

Anchoring materials

Rebar

Sand tubes

Lead line

Anchoring the net

Anchoring the Net

The completed plot

Net Maintenance

Damaged nets

Mending

Improper site maintenance!!!

Winter management

Results of ice damage

http://www.deq.state.va.us/Portals/0/DEQ/CoastalZoneManagement/task11-07-04a.pdf

One solution

Bottom bag culture

Other culture techniques

SC bottom cages for clams


Florida Soft Bags


Rolls of soft bag arrays with wire

Cedar Key hard clam farm

Florida clam boat

Harvest

Hydraulic Dredge

The Dredge and Pump Setup

Intake Hose

Outtake Hose

Pump

Working The Dredge

Maryland Clam Dredge

Grading clams

Quahog grading

Speed Rack aka Culling Box

Tumbling grader

Clam Roller

Hydroponic pumice

Alternative Shellfish Species

for Farming in the Northeast U.S.

Dale Leavitt Professor Marine Biology &

Aquaculture Extension Specialist

It is risky to put all of your eggs in one basket! • Need to diversify crop

• Economic

• Disease

• There is a continual effort to identify alternate species for culture and to develop technologies to culture them commercially

Selecting alternative species

• The criteria for the selection of aquatic animals suitable for large-scale production may fall into three major categories:

• Marketing

• Biology

• Operations

Selection Factors

• Marketing • Demand • Taste and Flavor • Appearance • Texture • Market behavior • Processing considerations

• Biology • Growth rate • Packing tolerance & Shelf life • Seed production • Hardiness

• Operations • Available sites • Culture technologies • Management systems • Financial requirements

Potential alternative species (infaunal species) • Soft shell clam (Mya arenaria)

• Surf clam (Spisula soldissima)

• Razor clam (Ensis directus)

• Blood ark (Anadara ovalis)

• Bay scallop (Argopecten irradians)

• Sea scallop (Placopecten magellanicus)

• Mussel (Mytilus edulis)

• Green sea urchin (Strongylocentrotus droebachiensis)

• Sugar kelp (Saccharina latissima)

Soft shell clam (Mya arenaria)

• AKA

• Steamer clam

• Pisser clam

• Long-neck clam

• Infaunal bivalve

• Prefers sand to sandy mud

• “Cold water” species

• Digs deep – predator avoidance

• Relatively static once established

• The traditional steamer clam in the northeast

• Market well established and strong

Soft Shell Clam Environment

Strong history of culture

• Started in beginning of the 20th century

• Manipulated sediment surface to attract natural set

• Moved large blocks of peat and Spartina grass

• Directed attempts to farm in 1940’s

• Moved beds of high density seed clams to alternative sites

Modern era - soft shell clam culture

• Mid-1980’s – Beals Island Regional Shellfish Hatchery (BIRSH)(ME)

• Focus on public enhancement

• Also supplied seed for private aquaculture attempts

• Now called the Downeast Institute with a shellfish hatchery on the premises

• Late 1990’s – Salem State University (MA) established a soft shell clam culture program

• Provides seed to municipalities and also to private growers

Public Aquaculture

• Large effort in enhancement of soft shell clam stocks

• Throughout northeast region

• Subsidizes the hatchery production of seed for development of private farms

Current status of soft shell clam culture • In the past 10

years, soft shell clams have made the transition from experimental to commercial

• Supported primarily by catching wild seed - using some variation of the clam tent

• Hatchery seed now being used in areas where wild seed harvest not successful

Seed Sources

• Hatchery

• Downeast Institute for Applied Marine Research & Education - http://downeastinstitute.org/

• Beals Island, ME

• Kyle Pepperman – contact person [email protected].

• Salem State University – Cat Cove Lab

• Salem, MA

• Scott Weston – contact person [email protected]

mailto:[email protected]



Downeast Institute Clam Seed Price

Soft Shell Clam seed

Another source of seed: Collecting Natural Set

Clam Tents

Some things you need to know:

• Grown in the intertidal

• No good technology for subtidal

• We currently have a grower in RI trying it subtidally

• Obligate infaunal clam

• Once it achieves a size of ~3/4” (20 mm) it must be in sediment

• Uses similar nursery/growout technology as quahog culture

• Upweller nursery

• Growout under netted raceways

Clam Caps

• Semi-rigid cap for placing over small raceways of clams

• Constructed from Vexar (Tenax)

• Configured as 3’ x 6’ caps

• Can be handled by one individual

• Plant seed then place cap over the top

• Hold to substrate with wire staples

Field plant under nets

20-50 individuals per ft2

Maintenance

Harvest

• Relatively deep burrower

• Intertidal

• Hand digging

• Hydraulic harvester

• Subtidal

• Hand harvest (fanning)

• Power assisted (air or hydraulic)

Bottlenecks – Soft shell clam

• This one seems to have made it over the commercial scale production hump

• Hatcheries can supply seed

• Technology to growout is available

• Market is relatively strong – particularly in summer

• Currently have both public and private culture activities ongoing

Biggest problem (in Mass) is political friction between wild harvesters and farmers

Surf Clam (Spisula solidissima)


• Largest bivalve along the east coast (6 - 8”)


• Lives in high energy sand to deepwater habitats

• Shallow burrower

• Dynamic and mobile

• Traditional harvest for the chopped clam market

• New product - 2” “steamer”

History

• Interest developed for farming surf clams in the 1980’s • at the NMFS Milford Lab

• Commercial scale production attempted in early 1990’s on Cape Cod

• Suggested product was a 2” size for the steamer market • Marketed as “butter clams”

• Advantages • Cold hardy

• Fast growth in warm water culture conditions, i.e. near-shore

• Highly attractive product

Surf Clam Technology

• Have experimented with a number of growout technologies

• Two seemed to work

• Florida soft bags

• Square mesh “suitcases”

• Clam “required” to be in sediment by ~¾” (20mm)

Surf Clam Technology

• Most productive is growout under netted raceways

• Less effort per surface area

• Market size (2”) in 18 months

• Harvest

• Traditional hand rake

• Need to purge sand

Bottlenecks – Surf Clam


• High summer mortality if placed in the intertidal or in warm water location

• Subtidal technology needed to minimize risk of summer overheating

• Availability of seed

• No hatcheries routinely producing seed

• One in MA is currently has surf clam seed for sale

• Must purge sand prior to market

• Market for “Butter Clam” needs to be further developed

Stimpson’s Surf Clam (Mactromeris polynyma)

However…. 1 year’s

growth!!!

Razor Clam (Ensis directus)


• Lives in low intertidal to subtidal

• Another “cold water” species

• Burrows deep

• Dynamic and highly mobile

• Will leave if conditions not to its liking

• Conventional harvest

• Historically for shucked product

• More recently sold live

Razor Clam Environment

History

• Interest perked up in early 2000’s when wild harvest value jumped to $2.00/lb

• NRAC supported a preliminary study to investigate growout technology

• Finished in Dec 2003

• Distributed razor clam seed to established clam growers to try their best technology

• SEMAC contracted for another round of razor seed for grower evaluation

• NRAC has funded a new studies to look at improving seed production in the hatchery

Razor Clam Technology

• Hatchery

• successful with typical protocols

• Setting

• Set marginal in downwellers

• Set on sediment – YES!!!!!!

• Nursery

• All traditional technologies worked

• Had problem with protozoan contamination during early post-set

Razor Clam Technology - Growout

• Different growers tested technology

• The results ranged from

• complete emigration within a week

• >90% retention/survival with strong growth

• Best technology

• In situ wooden box with mesh cover

• Harvest

• Hand dig

• Salt

Our current state of knowledge

• Hatchery stage • Razors can be held and handled in a similar manner to surf

clams and other “cold-water bivalves”

• Spawning, larval culture and setting are straightforward and easy to accomplish

• Nursery stage • They grow like weeds (ADG >0.25mm/day)!!

• Early post-set juveniles are highly susceptible to microbial problems when held in conventional downwellers

• Require high maintenance with excessively clean rearing conditions

• A quick and dirty experiment indicated that immediate planting in sediment may be a viable alternative to post-set downwelling (cannot be “sharp” sand).

Our current state of knowledge

• Growout stage • The growth rate is on a par with (and potentially better than)

the growth of wild razors in the North Sea (the only growth data we could find!)

• Preliminary data suggests that planting densities should be kept below 1,000/m2 (~100/ft2)

• Razors will grow through the winter under some conditions

• Market size individuals (app. 4-inches) can be harvested in two growing seasons following “field-planting”

• Emigration and overheating of sediment (in intertidal) are two problems that need to be considered in selection of site and technology used

• Best technology includes effective containment to prevent emigration => bottom trays or boarded raceways

• Needs to be stressed!!!

• Probably cannot grow in intertidal zone from Cape Cod to south

Bottlenecks – Razor Clam

• Seed • Hatchery seed - a potential problem!

• Currently – early post-set survival unpredictable

• No economic incentive to produce seed

• Need to refine best method to growout • Optimal habitat or best containment

technology?

• Also have summer overheating problem

• Market development may be required • Market product is 4” razor clam

Considerations • Seed sources

• Hatchery seed - a potential problem! • Currently – early post-set survival unpredictable

• Availability of seed • Not often commercially spawned

• No economic incentive to produce seed (Chicken & Egg)

• Seed Fragility • Shells can’t close tightly

• Vulnerable to external environment • NO fresh water

• NO harsh handling/spraying

• Sediment • Early placement optimal

• Sediment type is important • NO mason’s sand/sharp sand

Considerations • Need to refine best method to growout

• Optimal habitat or best containment technology?

• Temperature considerations

• Vulnerable to high temps (intertidal exposure)

• Mobility

• Can and will swim/dig/escape if unhappy with current environment

• Market development may be required

• Market product is 4” razor clam

• Identification of current or future markets

• Supply and demand must be balanced

Concluding Thoughts • Razor clams are a viable

alternative species for shellfish farmers in the northeast • Good price/market • Encouraging growth rate • Relatively simple (and

common) culture technology

• Still have some bugs to work out in • Post-set nursery to

achieve adequate seed supply for growers

• Growout methods

Blood Ark (Anadara ovalis)


• Primarily subtidal

• Prefers mud to muddy sand substrate

• Features

• Pronounced periostracum

• Strong byssal attachment

• Short-lived

• 3-5 years

• Unique clam

• Has hemoglobin in blood

Blood Ark Biology

• Fast growth

• Maximum size around 50 mm (2 inches)

• Prefers salinities above 15 ppt

• No siphons so remain at sediment surface and filter by gaping

• Spawns during summer

• Post-set frequently found in upwellers and other gear during early summer

Market

• Limited harvest

• Marketed mostly in Hispanic communities

• More recently

• Asian (akagai sushi)

• African

• Demand has been increasing

• Wild harvest cannot supply demand

Culture technology

• Hatchery techniques similar to those for the quahog

• 1 -2 million eggs per spawn

• Unique setting behavior

• May require benthic diatom for pedal-feeding

• Very heavy byssal threads

• Spat clump aggressively

Culture technology

• Experimentally grown in

• Soft (Florida) bags

• ADPI bags infiltrated with substrate (on-bottom)

• Planted at 50/ft2

Growth rate in Florida

• Achieve market size in 12 months

Bottlenecks

• Setting conditions need improvement

• Culture benthic diatoms for pedal feeding

• Novelty of the species

• Narrow ethnic markets that are expanding

• Lack of familiarity of species with most dealers and consumers

• Will require large marketing effort

The End

Quahog Grow-out - Applied Shellfish Farming

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