Quahog Grow-out (Plus a few other clams)

Transcription

1 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 mm (1.5 inch) What technology should I use? Dependent on location and species Categorize according to location in environment In Bottom Quahog & other infaunal clams On Bottom Suspended Floating Only real decisions Intertidal Subtidal 1

2 In Bottom Process Define planting bed Prepare bed Plant seed Cover Maintain Harvest Cover Netting 2

3 INTERNET Netting 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: clams/ft 2 Start at low density and build up Can plant smaller seed at higher density (500 clams/ft 2 ) if plan to thin out after first year. Example Wish to plant 100,000 seed at 75/ft 2 100,000/75/ft 2 = 1,333 ft 2 required 1,333/12 = 111 ft of mesh or ~ 100 foot net Mark out plot 3

4 Bed Preparation Another option? Hydraulic Option 4

5 Plant the seed Seed Prices Seed Prices 5

6 75 clams/ft 2 Covering the crop Anchoring the net 6

7 Anchoring materials Sand tubes Rebar Lead line Anchoring the Net The completed plot 7

8 Net Maintenance Damaged nets Mending 8

9 Improper site maintenance!!! Winter management Results of ice damage 9

10 One solution Other culture techniques Bottom bag culture 10

11 Other culture techniques SC bottom cages for clams Other culture techniques Florida Soft Bags Rolls of soft bag arrays with wire 11

12 Cedar Key hard clam farm Florida clam boat 12

13 Harvest 13

14 Hydraulic Dredge The Dredge and Pump Setup Pump Outtake Hose Intake Hose Working The Dredge 14

15 Grading clams Quahog grading 15

16 Speed Rack aka Culling Box Tumbling grader Clam Roller 16

17 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 17

18 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) 18

19 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 20 th 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 19

20 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@downeastin stitute.org. Salem State University Cat Cove Lab Salem, MA Scott Weston contact person scott.weston@salemstate.edu 20

21 Soft Shell Clam seed Another source of seed: Collecting Natural Set 21

22 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 22

23 Field plant under nets individuals per ft 2 Maintenance Harvest Relatively deep burrower Intertidal Hand digging Hydraulic harvester Subtidal Hand harvest (fanning) Power assisted (air or hydraulic) 23

24 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 24

25 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 25

26 Stimpson s Surf Clam (Mactromeris polynyma) Stimpson s Surf Clam (Mactromeris polynyma) However. 26

27 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 27

28 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 28

29 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 29

30 Culture technology Experimentally grown in Soft (Florida) bags ADPI bags infiltrated with substrate (on-bottom) Planted at 50/ft 2 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 30

31 The End 31