An important but slightly challenging sector of aquaculture is oyster farming. The farming method has ancient roots and popular in France, Italy and England. Historical data can be traced to 1st century BC ancient Romans on the Italian peninsula. And the origins of modern oyster farming started with Hyacinthe Boeuf.
Interestingly oysters can live for 30 years and are sequential hermaphrodites. The business is challenging and difficult to control and there are so many variables especially theses farmed in natural condition. Here are some ideas on how to start an oyster farm.
The major challenges are environmental issues, and predators. Others include dealing with pests and certain diseases. The main predators are crabs, birds, stingrays. Others are drill snails, starfish and humans. The two major infections or diseases are MSX and Dermo.
- environmental issues
- certain diseases
Selecting the Right Species to Farm
The selection process will determine the success or failure of the farm. The criteria should be based on meat content and shell depth. Others are disease resistance, fast growth rate and adaptability to the location.
- meat content
- shell depth
- disease resistance
- fast growth rate
- adaptability to the location
- rabbit farming
Types of Growth Systems
The farming methods are diverse and interesting. The farmer needs to develop the technique and perfect a particular growing system. Common systems are the suspended culture, traditional bed and bottom culture system.
Inter Tidal Long Line System
We also have the inter-tidal long line system. This is a suspended method where baby oysters and mature ones set on them. They are then inserted into the strands of a rope.
The shells are then spaced out and rope stretched along the ground. The area should be low tide and ropes supported about above the ground. This instigates faster growth than the mud system. The major disadvantages include competition with other sea life and unpredictability of tidal waves.
The Suspended System
The suspended system is similar to inter-tidal system. However the oysters are placed in nets or trays and suspended in sub tidal waters.
The Rack and Culture System
The rack and culture system involves plastic bags supported above ground on steal racks. This is to enable water flow around the oysters. The system is very effective at preventing predators like crabs. The bottom culture is when the oysters are allowed to grow on the ground of intertidal regions.
Types of Oyster Farming Culture Systems
- bottom culture system
- rack and culture system
- suspended system
- inter-tidal long line system
To cultivate oyster the broostock should be cultivated. Broodstock provides gametes to larvae and spawning is carried out simultaneously. Prefect natural conditions for growth are blackish water or estuarine bodies.
By separating the ripe oysters the farmer can mimic ideal conditions. Farmers are able to simulated all year round spawning. To achieve this farmer needs to build a recycling system that allows the introduction of a diversity of phytoplankton.
They manipulate temperatures of heat and cold to induce spawning in ripe oysters. The water quality is tailored to particular species the farmer wants to spawn. The usual practice is to separate a large number of ripe oysters and place in the system. This is because determining the gender is slightly challenging.
Once spawning commences the sperm and eggs are fertilized through mixing. Then the fertilized larvae are the fed cultured algae. It is important maintaining clean water in the system.
They should change the water every two days to prevent foreign organisms competing with the oyster larvae. Once they develop an eyespot they are ready to set. Oysters generally attach themselves to surfaces so the farmer provides a clutch or substract.
They are put in the system, clutch and start to mature properly. They can mature naturally or the spat are placed in bags to retrieve matured oyster during cultivation.
Another method is placing the spat in a clutch or artificial maturing tank. The salinity and temperature are altered and the seed are feed prepared water for accelerated growth. This method is very effective but highly expensive.
Mud Planting Technique
The young oysters are packed in bags and placed in a cage system to bulk up the nursery. The cages rest at the bottom of the designated bay for about 3 months. Then Oysters of certain age are removed from nursery and scattered in a bay area.
They are left to grow for two years then harvested from the bottom of the lake with a rake system. The farmers then pick the big ones with well rounded shape and discard the weird looking ones.
Types of Oysters Farmed
There are five popularly farmed oysters. We have the southern mud oyster and eastern oyster. Others include Sydney rock oyster, pacific oyster and Belon oyster.
- Mud oyster
- Eastern oyster
- Sydney rock oyster
- Pacific oyster
- Belon oyster
Growing Area for Oyster Farming
There are many things that determine a suitable site for oyster farming. Apart from government zoned locations the site needs to conform to serious environmental issues.
The growing area is determined by environmental impact on oysters. Unsuitable areas locations are those that have storm water runoff, sewage or industrial pollutants.
Commercial farmers are mandated to monitor the level of bacteria contaminants, phytoplankton species and geotaxis in the location. During floods the banks should not be exposed to wave action or tidal currents.
Problematic areas are those with shifting sands because such conditions damage the oysters. The currents should supply the oyster’s adequate water and ensures rapid growth, proper nutrients.
If the farmer considers an off shore area it should be close to land facilities. Other consideration when choosing a land is accessibility to ready market or processing area.
Based on the land use criteria stipulated above the authorities would determine suitability of the area. They also have harvesting criteria and provide restrictions appropriately.
Challenges include fattening areas or spat production areas. Another determinant is the culture methods. Oyster farming is lucrative however the farmer needs lots of patience.
Pearl Oyster Farming
Pearl farming is the cultivation of oyster for the production of pearl. Although cultivated in the wild there are few local commercial small hold farmers. The process involves collection of wild pearl oysters followed by hatchery operations before seeding. The process of farming includes seeding or insertion to stimulate pearl growth.
There are different pearl oyster species farmed for pearl production. One of the most lucrative is the south sea pearls with the largest in Western Australia estimated at $80 million in 2017.
Oyster farming for pearls is very profitable and sustainable. There are many products with premium value produced in the industry. However the industry is highly specialized and requires good knowledge of commercial farming. Products include different grade pearls, white pearls, jewelry, string pearls, buttons and pearl meat.
- grade pearls
- white pearls
- string pearls
- pearl meat
Great care is given to the oyster for rapid growth and good health. This is mandatory to produce unblemished high grade pearls. The oysters are kept in stress free environment, regular cleaning to get rid of parasites and clean water. Seeding is done by a professional with great care.
Hatchery and Wild stock cultivation of pearls
There are three methods used in oyster pearl production hatchery method, wild stock gathering or a combination of both methods. Hatchery involves use of brood stock to produce juveniles.
However wild stock cultivation of pearl is very challenging, capital and labor intensive Wild stock involves divers handpick stock from ocean bed using specialized pearling-boats. On the boats the expert seed the oysters then return them to ocean bed. To safeguard the stock the oysters are placed in net panels.
On the other hand the oyster are carried to a laboratory and seeded before they are returned to the ocean bed. In the cause of 90 days the net-panels are turned regularly before they are moved to farms.
Farm technique includes floating lines placed in pristine waters for better yield. It takes 36-48 months before the pearls are harvested from the oyster. A usual practice is to re-seed the oyster and return to the farm for new pearl production.