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Quahog Grow-out (Plus a few other clams)

Dale Leavitt

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

• Subtidal

Quahog & other infaunal clams

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In Bottom

Process

• Define planting bed

• Prepare bed

• Plant seed

• Cover

• Maintain

• Harvest

Cover Netting

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Netting

INT

ER

NE

T

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

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Bed Preparation

Another option?

Hydraulic Option

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Plant the seed

Seed Prices

Seed Prices

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75 clams/ft2

Covering the crop

Anchoring the net

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Anchoring materials

Rebar

Sand tubes

Lead line

Anchoring the Net

The completed plot

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Net Maintenance

Damaged nets

Mending

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Improper site maintenance!!!

Winter management

Results of ice damage

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One solution

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

Bottom bag culture

Other culture techniques

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SC bottom cages for clams

Other culture techniques

Florida Soft Bags

Other culture techniques

Rolls of soft bag arrays with wire

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Cedar Key hard clam farm

Florida clam boat

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Harvest

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Hydraulic Dredge

The Dredge and Pump Setup

Intake Hose

Outtake Hose

Pump

Working The Dredge

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Grading clams

Quahog grading

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Speed Rack aka Culling Box

Tumbling grader

Clam Roller

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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

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Selecting alternative species

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

• Marketing

• Biology

• Adaptability of the organism

Selection Factors

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

• Biology • Growth rate • Packing tolerance & Feed availability • Seed production • Hardiness

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

Potential alternative 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)

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Soft shell clam (Mya arenaria)

• 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

Strong history of culture

• Started in beginning of the 20th century

• Manipulated sediment surface to attract natural set

• Directed attempts to farm in 1940’s

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

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

• Provides seed to municipalities and also to private growers

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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

• Beals Island, ME

• Kyle Pepperman– contact person kyle.pepperman@downeastinstitute.org.

• Salem State University – Cat Cove Lab

• Salem, MA

• Scott Weston – contact person scott.weston@salemstate.edu

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Soft Shell Clam seed

Another source of seed: Collecting Natural Set

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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

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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)

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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)

• Infaunal bivalve

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

• “Cold water” species

• 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

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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

• “Cold water” species • 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

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Stimpson’s Surf Clam (Mactromeris polynyma)

Stimpson’s Surf Clam (Mactromeris polynyma)

However….

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Razor Clam (Ensis directus)

• Infaunal bivalve

• 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

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 study to look at improving seed production in the hatchery • Started Summer 2012

Razor Clam Technology

• Hatchery

• successful with typical protocols

• Setting

• Set okay in downwellers

• Set on sediment?

• Nursery

• All traditional technologies worked

• Had problem with protozoan contamination during early post-set

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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

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

Blood Ark (Anadara ovalis)

• Infaunal bivalve

• 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

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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

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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

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The End