GROW YOUR OWN OYSTERS!!!

PROGRAM OVERVIEWClass visit 1: Introduction and biology of

oystersExcursion 1: Tour of local estuary and oyster

processing facilityClass visit 2: Oyster productionExcursion 2: The business of oyster farmingClass Visit 3: Improving operationsExcursion 3: Harvesting and marketing

Today . . . . .The importance of aquaculture

Various cultivation methods used to farm oysters

The oyster growing process

Aquaculture Aquaculture is the

rearing or cultivation of aquatic animals or plants for food in natural or controlled environments e.g. oysters, mussels, salmon, tuna

Mariculture refers specifically to the culture of marine organisms

So why farm seafood?

Increasing pressure on wild fish stocks means aquaculture is a growing industry

Increasing demand for high quality seafood that can’t be met with wild stocks

Relieve pressures on wild fisheries

How are oysters grown?Oyster farming operations can be broadly

divided into three stages:Spat collectionOn-growingHarvesting

Spat collection

Wild larvae previously caught on tarred wooden sticks

Sticks placed in areas where spatfall (settling of spat) most reliable

Sticks often moved to low spatfall areas to reduce ‘overcatch’

Oysters then knocked off these sticks around 6 months of age

Plastic catching slats used today

On-growingVariety of techniques used to grow oysters

Broadly grouped into two groupsTray cultureLongline system

Tray culture Some form of container or tray that sits on

supporting rackTrays typically 1.8 x 0.9mTimber frame with plastic mesh bottoms,

placed on timber racksMain advantage: allow precise stocking

densities

Longline or floating culturePlastic systems have been developed to

reduce the amount of tarred timber used in cultivation

Baskets, bags and tumblers are usedSome oysters grown subtidally on rafts or on

floating culture Floating culture: gear moves through the

water column with the tide

Husbandry requirementsFilter feeders - require clean waterWater testing and meat testing conductedOysters need to be graded – sorted into

similar-sized groupsDrying oysters

Strengthen the adductor muscleKill off overcatchReduce risk of mudworm (parasite)

A timeline of operationsCatch slats put out for oysters to settle on

(Feb)Spat stripped from catch slats, graded and

put into nursery lease in fine mesh bags (Nov)Grading and thinning occurs every 3-6

monthsOysters that are continually in the water

need to be dried outFor harvest: clean mud off oysters, remove

dead oysters, grade, bag up

Any questions???Next excursion: the business of oyster

farming