Transcript One Hour Brief Presentation - NSW South Coast Oyster Industry

Oyster farming on the insert estuary
name here
What are oysters?
•
•
•
•
Bivalve molluscs
Filter feeders
Can filter up to 5L of water an hour
Feed on phytoplankton (microscopic plants) that they filter from
the water column using their gills
Oyster farming…
• Oysters grow wild in rivers and lakes, but….
• They are commercially farmed.
Where are oysters farmed around the world?
•
•
•
•
•
•
•
•
Australia
New Zealand
France
Ireland
USA
Japan
China
EVERYWHERE!
Three types of oysters farmed in Australia….
• Sydney Rock oysters
• Pacific oysters
• Angasi (Native) oysters
Where are oysters farmed in Australia?
Where are oysters farmed
on the NSW south coast?
Shoalhaven River
maximise their investment (Stasko, 2000). Shell beds and stones supported on poles were
used to catch and grow oysters. Over time, cultivation of oysters has evolved to the use of
rack & rail and long-line cultivation systems (see section 4.2).
History of oyster farming on the insert
estuary name here
Production levels in the estuary have varied considerably over time. Peaking in the 1980’s &
90’s, the estuary at this time was accounting for roughly half of the state’s total production of Sydney rock oysters. Although production levels of Sydney rock oysters have dropped
slightly in recent years, many farmers have been diversifying into Pacific oysters, and
production of this species is not represented in the chart below.
• First farmed in 1883 (130 years ago!)
How many oyster farmers are there?
• South coast
= 100 farmers
• Shoalhaven River
= 15 farmers
• Shoalhaven Heads
= 1 farmer
Shoalhaven Oyster Farmers…
Oyster external anatomy
 Umbo – pointed end of the oyster, is the oldest part
 Valves – the two shells of the oyster, made up of 98%
calcium carbonate
 Hinge – area formed by the joined valves
Anterior
Posterior
Mantle
• Two fleshy folds of tissue
• Cover the internal organs
• Always in contact with
the shell but not attached
• Principal role formation
of shell
Gills
• Largest organ in oyster
• Each gill consists of 2
folds of tissue
• Primary role is
respiration
• Also creates water
currents, collects food
particles and transports
them to the start of the
digestive system
Tentacles
• Small sensory organs
• Attached to edge of
mantle
• Used to detect
environmental stimuli
Adductor muscle
• Muscle responsible
for opening and
closing the valves
• The weight of this
muscle accounts for
20-40% of the soft
tissue weight of an
oyster
Digestive gland
• Produces digestive
enzymes
Other parts of the oyster
•
•
•
•
•
•
•
•
Gonad
Heart
Intestine
Visceral mass
Mouth
Oesophagus
Stomach
Anus
How are oysters farmed?
• Three main stages:
– Spat collection
– On-growing
– Harvesting
How long does it take to grow an oyster?
• Pacific Oyster –
about 18 months
• Sydney Rock Oyster –
up to 3 years!
Who buys the oysters from the farmer?
•
•
•
•
Processors
Restaurants
The public (people traveling the ‘Oyster Trail’)
Overseas (export)
Oyster farming and the environment
• Water quality is the most important thing in oyster farming.
• Why?
• Oysters are filter feeders. They eat whatever’s in the water.
Good…
Bad…
How oyster farmers keep the water clean
•
•
•
•
Use cleaner equipment
Encourage others to do the right thing
Work to fence off areas from cattle
Monitor! All the time!
How oyster farmers keep the water clean
• Environmental Management System (or ‘EMS’)
– We know the issues
– We have actions in place to address the issues
How you can help the oyster industry
•
•
•
•
Keep the river clean
Tell others to keep the river clean
Report incidents (www.oystercoast.com.au)
Buy local oysters