Shellfishery(Shellfish Culturing)

By

Nida SajjadSubject : Economic Zoology

Mphil Zoology University of Sargodha

An introduction to Shellfish & Shellfishery

• Shellfishery is the industry and commerce of catching, processing, and selling shellfish; raising shellfish for commercial purposes.

Why do we need to culture shellfish???Shellfish is mainly cultured for nutritional values as it is rich in

proteins, vitamins(A,B,D) and low in fats. It contains many minerals.

Marine molluscs enjoyed as a food source by humans include many species of clams, mussels, oysters and scallops.

Some crustaceans commonly eaten are shrimp, lobster, crayfish, and crabs.

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There are three types that are commonly eaten:Bivalves have a pair of hinged shells (like clams,oyster,mussels and

scallop)Univalves have a single shell (like conch,abalone)Cephalopods have a single thin internal shell called a cuttlebone

(like octopus,squids,cuttlefish)

Shellfish(Molluscs)

Those with one shell are known as Gastropods.

Conch clamsoctopus

Cephalopod

Molluscs Cultivation

• It includes cultivation of following groupsMussel CultivationScallop CultivationAbalone CultivationClam CultivationOyster Cultivation

Scallops

Oysters

MUSSEL CULTIVATION• The majority of culture takes place in temperate

climates and in Europe. Spain, the Netherlands, Denmark and Italy the leading producers, along with China. • Primary Species being culturedBlue musselMediterranean mussel Green mussels

Methods to Cultivate Molluscs (An Overview)

1.Bottom Culturing (Type 2 Production system)• Culturing on the seabed and promoting enhanced fishery.• It is two-dimensional production system.2.Suspended Culturing(Type 1 Production System)• It is Three-dimensional production system.• include following structures.Long lineRaftsPoles

Bottom Cultivation(Type 2 production system)

It is cultivation of mussels on the seabed in intertidal(littoral) zone.

Steps for bottom cultivation1.Spat collectionSpat are collected at an age of 1 year old, when they measure

between 10-30mm shell length (SL). 2.HarvestingBottom cultured mussels can be harvested by many methods like

mechanized dredging, simple hand-collection or hand-raking(Shovel like equipment).

Suspended culture. A. Longline cultivation(Structure)Its arrangement consists of a series of horizontal ropes that are held in the top 3m of the water column by floats.From the headlines series of dropper ropes hanged, which carry the mussels.

B. Pole culture (Bouchot method)

is a shallow water technique.StructureBouchots are vertical, made of

wood or plastics pushed into the ground parallel, around which ropes made of fibers used to grow the mussels are tied in a spiral.

For this method the spat are collected on poles.

C.Raft CulturingThe use of rafts is popular and is utilized by

many countries including Australia, Chile, USA, Ireland, Scotland, Singapore and Venezuela.

StructureWooden beams are supported by plastic foam-

filled floats. synthetic ropes are spaced along the beams.

SCALLOP CULTIVATION

It started in the 1930 s in Japan.Only 33 species are viewed as

commercially important.Culturing method can be classified as a

type 2 production system.Longline method is used for spat collection

ABALONE(Herbivore gastropod) CULTIVATIONAbalones are gastropod molluscsCulturingBarrels and cages are suspended from longlines

for the growout of abalone.Diet: They feed on algae and benthic diatoms

by scraping away the layers with their radula.

Clam CulturingCalifornia is a leading supplier of clam seed

worldwide.Clams include cockles, razor-clams, manila

clams, and quahogs among others.Broodstock Clams in Closed System Raceways

Economic Importance

Clams are cutured for lime production.Oyster and mussel shells are used as poultry or fish meal.Oyster shells are used to make homeopathic medicines as shell

extracts.Shells of bivalve are used to make decoration pieces and jewelries.