Coastal Aquaculture and Mariculture (2+1)

Unit 1 - Shore based aquaculture and mariculture

1.2.4.Molluscs

Bivalves are a major component of aquaculture production in the Asia-Pacific region. Much of this production is based on the culture of mussel, which is a high-volume, low-value commodity. In the Asia-Pacific region, Thailand and the Philippines are the largest producers of farmed mussels primarily the green mussel (Perna viridis). At the other end of the spectrum, there has been substantial production of pearls through farming, which produces an extremely low-volume but high-value product.

Despite the fact that hatchery production technologies have been developed for many bivalves, most tropical bivalve culture still relies on collection of seed stock from the wild. Artificial settlement substrates such as bamboo poles, wooden stakes, coconut husks or lengths of frayed rope are used to collect bivalve spat at settlement. The spat may be transferred to other grow-out substrates (“relayed”), or cultured on the settlement substrate.
Molluscs - culture methods

There are two major systems commonly used for bivalve culture

• On or just above the bottom – This culture system is commonly used for culture of bivalves that tolerate intertidal exposure, such as oysters and mussels. Rows of wooden or bamboo stakes are arranged horizontally or vertically. Bivalves may also be cultured on racks above the bottom in mesh boxes, mesh baskets, trays and horizontal wooden and asbestos-cement battens.
• Surface or suspended culture – Bivalves are often cultured on ropes or in containers, suspended from floating rafts or buoyant long-lines. Management involves thinning the bivalves where culture density is too high to support optimal growth and development, checking for and controlling predators, and controlling biofouling. Tropical mussels grow to market size (about 5–7 cm shell length) in less than one year, and in many cases 6–7 months, after settlement. Production can reach 1 800 tonnes per ha annually but may be lower in some areas. With a cooked meat yield of around 20 percent, this is equivalent to 360 tonnes of cooked meat per ha per year). In Asia, farmed mussels are generally sold as whole fresh product. Some products are simply processed, e.g. shucked and sold as fresh or frozen meat. There has been some development of longer-life products, including canned and pickled mussels.

Mussel culture methods

Mussels rafts



On-bottom culture of oysters


Off-bottom culture of oysters

Cage culture of oysters



Suspended culture of oysters


Stake culture of oysters