Mollusc Aquaculture

Phylum Mollusca ~85,000 extant species

Well Represented in Fossil Record

10 classes: 3 Important in Aquaculture

Bivalvia, Cephalopoda, Gastropoda

Most Important are the Bivalves: Scallops

Oysters, Clams, Mussels etc.

Some Life Cycles have been Closed, Most

Have Not, Must Fish Young from Wild.

Mollusc Aquaculture

A Roman Form of Marine Aquaculture

Many Sessile Filter Feeders

Often Open Water Natural Habitats

with Young (Sprat) Collected Locally

Polyculture advantageous Tilapia, Shrimp

35% of Total Aquaculture Production

Scaphopods

Tusk or Tooth Shells

Native American Money

Mollusc Aquaculture

Culturing Pearls: Both FW and Marine Pearls

Oyster, Abalone, Mussel & Black Pearls

Bivalves: Oysters, Mussels, Scallops, Clams

Gastropods: Marine, FW and Terrestrial

Abalone – Valuable Dried Seafood Hong Kong

Chile has Cage Culture of California Red

Abalone (Haliotis rufescens)

Cephalopods – Thailand - Culture Squid and

Cuttlefish? Young Fished from Wild Pop’ns

Bivalve Aquaculture

Oysters Number 1 Aquacultured Bivalve

China leads world: Japan, Korea & France.

Crassostrea gigas – More Abundant

Ostrea – More Valuable – Eaten Raw

Most Grown at Higher Temperatures

Contamination with Pathogenic Bacteria

Filter Feeders – Concentrate Pathogens

Vibrio spp., Toxic Algae – PSP, etc

Bivalve Aquaculture

Simplest Culture is on the Bottom

Sow Bivalve Shell (Cultch) Larva will settle on it.

Best off Bottom: Avoid Predators, Oyster Drill Snail

Starfish – Upogebia - Burrowing Ghost Shrimp

Can Suffocate Oysters

Depurate – to Cleanse, Purify or Purge

Bivalves: Feeding Concentrates Toxins & Pathogens

Hold Harvest in Running Water Until Gut Emptied

Cornmeal - Unlikely to Remove PSP.

Paralytic Shellfish Poison (PSP)

Toxins from Marine Dinoflagellates

(Algae) in the Genus Alexandrium.

Accumulates in Filter Feeder Tissues

Can Remain for Months or Years

Most Common PSP is Saxitoxin. Acts on

Voltage-Gated Sodium Channels

Can be Fatal –Numbness, Paralysis,

Respiratory Failure

Oyster Aquaculture

Oysters Tolerate Fluctuating Water Quality

Alaska has Significant Oyster Farming

Cold Waters Improve Texture & Taste

PSP Rigorously Monitored (FDA)

Oysters are Generally Protandrous Animals

Juveniles Develop into Males,

Later These Become Females

Life Cycle with Feeding Larva – The Veliger

Modes of Oyster Culture

Provide Con-Specific Shell on Bottom

Cultch - for Spat to Settle on.

Off Bottom Systems Provide Protection

from Predators and Fouling – Can Use

Stakes & Racks

Suspended Systems – Ropes or Trays

Suspended from Long Lines or Floats

Culture of Other Bivalves

Mussel Culture often on Rafts – up to 700

ropes from each raft – 60 mt per year per raft

Scallops (China Leads the World) Drill Holes

Adjacent to Hinge, Thread Through, Tie up.

Clams: China Dominant – Malaysia, Taiwan,

Korea, Italy & US. Infaunal Culture

Geoducks: In PVC pipes – Growout takes 3 yrs.

Technology from Washington State

Obtaining Spat

1. Monitor Local Waters & Harvest from Sea

Natural Settlement on Old Bivalve Shell

2. Purchase from Shellfish Hatchery

Seward Alaska – Alutiiq Pride Hatchery

Oyster Bottom Culture

Oyster Culture Sticks

Oysters: China Oyster Racks

African Oysters in Mesh Packs

Eating Oysters

Canadian Floating Oyster Farm

Raft Mussel Culture - Galicia Spain

Oyster Cultch ~ Hanging Scallop Shell

Korean Hanging Oyster Culture

Canadian Bag Oyster Harvest

Cultured Pearls

Freshwater Pearls: Mussel Family Unionidae

Marine Pearls: Oysters in Sheltered Lagoons

Tahitian Pearls ~ 55% French Polynesia Exports

Mexican: Sea of Cortez – Rainbow Lipped Oyster

Cultured Pearls

Seed Inserted into Ovary Produces Round Pearl

Spherical Seed from Mississippi Pig Toe Clam Shell

Pearl Culture

In 2009 China Overtook Japan as Leader

In Production of Cultured Pearls

2008 World Production of Pearls 1,500 mt

Value (2008) $1.5 Billion (US)

Considerable Religious References to Pearls

in both the Bible & the Koran

Pearl Culture

Pearl Oyster Farm

Mexican Rainbow Lipped Pearl Oysters

Freshwater Pearls

Akoya Pearl Necklace

Tahitian Black Pearls

Mussel Culture

Freshwater Mussels for Pearl Culture China

China First in Production, Spain (Galicia) 2nd

Pole Culture being Supplanted by Raft Culture

Marine Mussels Cultured for Food

Blue Mussel – Mytilus edulis (Atlantic)

Important Fall Food in Belgium & Netherlands

New Zealand Green Lipped Mussel

Perna canaliculis

Hanging Mussel Culture

Floats at a Mussel Farm

Mussel Culture

Cleaning Mussel Set Line

Mussel Culture

Mytilus edulis

Aquacultured Cockles

Clam Harvest

Pre-Settlement Larval Clams

Growing Algae as Food for Clams

Geoduck Farm

Geoducks

Scallop Hanging Culture: Floats & Baskets

Molluscan Trochophore Larva

Molluscan Veliger Larva

Namibia Abalone Farm

Abalone Shell Nacre

Abalone Nacre Stiletto Handle

Octopus vulgaris (Atlantic)

Octopus Embryos I

Octopus Embryos II

Octopus Paralarvae

Terrestrial Pulmonate Snails

French National Delicacy “Escargot”

Common in Cuisines around Mediterranean

In Medieval Britain called “Wall Fish”

Pulmonate Snails are Hermaphrodites

Acquire Calcium directly from Soils

Helix pomatia, H. aspersa are top species

US Snail imports 1990 $4.5 million

Harvest at the Snail Farm

Served as Escargot

French Snail Farm

Helix pomatia

Marine Prosobranch Snails