Presentation

On

Culture Method of

MusselPresented by

Md. Tariful Islam Fuad

ID. No.: 13207059

Marine Science

Session: 2012-13 (2nd Year)

Institute Of Marine Sciences & Fisheries,

University Of Chittagong.

MUSSELSMussels are one of the member of Mollusca

Cultured mussels speciesPerna viridis (green mussel)

Mytilus edulis (blue mussel)

Modiolus metcalfei (brown mussel)

Perna viridis is the only species farmed commercially.

Culture Methods

Mussel culture, as practiced in many countries, is carried out

by using a variety of culture methods based on the prevailing

hydrographical, social and economic conditions.

Mainly there are three types of culture methods-

• Bottom culture

• Inter-tidal and shallow water culture

• Deep water culture

Bottom Culture

Bottom culture as the name implies is growing mussels directly on

the bottom. In this culture system a firm bottom is required with

adequate tidal flow to prevent silt deposition, removal of excreta

and to provide sufficient oxygen for the cultured animals.

Production of seeds is completely left to nature. If the natural

spatfall grounds are unsatisfactory for growing, the seedlings are

transferred by the farmer to safer and richer ground or to his

private growing plots, until the marketable size is attained.

Marketable mussels are fished from the plots and undergo

cleansing before being sold. This method requires a minimum

investment. Practiced in The Netherlands.

This methods has disadvantages

like heavy predation, poor

Growth & relatively low yields

Per unit culture area.

Intertidal & Shallow water

culture

The culture methods that fall under this category

are usually practiced in the intertidal zone. The

culture facilities are set in such a way that the

mussels are submerged at all times. Intertidal &

shallow water Culture methods are:

• Rack culture

• Tray culture

• Wig-wam culture

• Rope-web culture

Rack CultureThis is an off-bottom type of mussel culture. Rack

culture is predominantly practiced in the Philippines

and Italy where sea bottom is usually soft and muddy

and tidal range is narrow. The process involves setting

of artificial collectors on poles or horizontal

structures built over or near natural spawning grounds

of the shellfish. In the Philippines, this is called the

hanging method of mussel farming. The different

variations used are as follows:

• Hanging method

• Stake(Tulos) Method

Hanging Method

The process starts with the preparation of the spat collectors.

Nylon ropes or strings, are threaded with coco fiber supported

by bamboo pegs or empty oyster shells at 10 cm intervals. These

collectors are hung on horizontal bamboo poles at 0.5 m apart. A

piece of steel or stone is attached at the end of the rope to

prevent the collector to float to the surface. Setting of

collectors is timed with the spawning season of the mussels.

Spats collected are allowed to grow on the collectors until

marketable size. Mussels are harvested by taking out from the

water the ropes or strings and bringing them to the shore on a

banca. The same collectors can be re-used after being cleaned

of fouling organisms.

Stake (Tulos) MethodThe stake method is midway between the rack and bottom

methods. Bamboo poles, 4–6 m in length are staked firmly at the

bottom in rows, 0.5–1 m apart during low tide in areas about 3.0

m deep and above.

In areas where water current is strong, bamboo poles are kept in

place by nailing long horizontal bamboo supports between rows.

Since mussels need to be submerged at all times, it is not

necessary that the tip of the poles protrude above the low water

level after staking. However, boundary poles should extend

above the high water level. In staking, enough space between

plots is allowed for the passage of the farmer's banca during

maintenance.

Collected spats are allowed to grow in-situ until marketable size,

5–10 cm after 6–10 months. It has been observed, that about

2,000–3,000 seeds attach on 1 metre of stake, 1–2 m below low

water level.

Stake (Tulos) MethodThe mussels are harvested by pulling out the poles

and bringing them ashore on a banca. Some poles

may still be sturdy and can be re-used during the

next season.

Tray CultureTray culture of mussels is limited to detached

clusters of mussels. Bamboo or metal trays, 1.5 m ×

1 m × 15 cm sidings are used. The tray is either

hang between poles like the hanging or stake

methods or suspended on four bamboo posts.

Wig-wam CultureThe wig-wam method requires a central bamboo pole serving as

the pivot from which 8 full-length bamboo poles are made to

radiate by firmly staking the butt ends into the bottom and

nailing the ends to the central pole, in a wigwam fashion. The

stakes are driven 1.5 m apart and 2 m away from the pivot. To

further support the structure, horizontal bamboo braces are

nailed to the outside frame above the low tide mark. Spats

settle on the bamboos and are allowed to grow to the

marketable size in 8–10 months.

Mussels are harvested by taking the poles out of water, or in

cases that there are plenty of undersized bivalves, marketable

mussels are detached by divers.

Rope-web cultureThe rope-web method of mussel culture was first tried in Sapian Bay,

Capiz, in 1975 by a private company. It is an expensive type of culture

utilizing synthetic nylon ropes, 12 mm in diameter. The ropes are

made into webs tied vertically to bamboo poles. A web consists of two

parallel ropes with a length of 5 m each and positioned 2 m apart.

They are connected to each other by a 40 m long rope tied or fastened

in a zigzag fashion at an interval of 40 cm between knots along each of

the parallel ropes. Bamboo pegs, 20 cm in length and 1 cm width are

inserted into the rope at 40 cm interval to prevent sliding of the crop

as it grows bigger.

In harvesting, the rope webs are untied and the clusters of mussels are

detached.

Deep Water Culture

There are two methods followed for deep

water culture-

• Raft Culture

• Long-line culture

Raft CultureMussel raft culture has been practiced in Spain for a long time. Mussel seeds

that settle freely on rocks or on rope collectors are suspended from a raft.

When the weight of the bivalves on a given rope exceeds a certain limit, the

rope is taken out and again distributed over a greater length until marketable

size. It is a continuous thinning of the mussel stock to provide ample space to

grow.

The raft may be an old wooden boat with a system of outrigger built around

it. Other kinds of rafts could be a catamaran-type boat carrying some 1000

rope hangings, or just an ordinary plain wooden raft with floats and anchors.

Floats can be made of plastic, wood, oil drums, etc. The raft are transferred

from one place to another using a moto-boat. Production of mussels from this

type of culture is high. From a catamaran-type raft with 1,000 rope, 6–9 m in

length, about 4,666–5,333 MT of marketable mussel can be produced

(Korringa, 1976)

Advantages : reduce predation,

utilization of planktonic food at

all levels of water & minimum siltation

Long-line culture

Long-line culture is an alternative to raft culture

in areas less protected from wave action. A long-

line supported by a series of small floats joined by

a cable or chain and anchored at the bottom on

both end is employed. Collected mussel spats on

ropes or strings are suspended on the line. The

structure is fairly flexible.

Thank you everyone.