Culture Methods of Mussels

Culture Methods of Mussels

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  Presentation On Culture Method of Mussel Presentedby Md. Tariful Islam Fuad ID. No.: 13207059 Marine Science Session: 2012-13 (2nd Year) Institute Of Marine Sciences & Fisheries, University Of Chittagong.
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  MUSSELS Mussels are oneof the member of Mollusca
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  Cultured mussels species Pernaviridis (green mussel) Mytilus edulis (blue mussel) Modiolus metcalfei (brown mussel) Perna viridis is the only species farmed commercially.
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  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
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  Bottom Culture Bottom cultureas 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.
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  Intertidal & Shallowwater 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
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  Rack Culture This isan 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
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  Hanging Method The processstarts 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.
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  Stake (Tulos) Method Thestake 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.
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  Stake (Tulos) Method Themussels 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.
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  Tray Culture Tray cultureof 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.
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  Wig-wam Culture The wig-wammethod 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.
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  Rope-web culture The rope-webmethod 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.
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  Deep Water Culture Thereare two methods followed for deep water culture- • Raft Culture • Long-line culture
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  Raft Culture Mussel raftculture 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
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  Long-line culture Long-line cultureis 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.
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  Thank you everyone.