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PRESENT STATUS OF MUSSEL CULTURE IN INDIA

mussels


Submitted by:

Kotia Tushar Jadav

M.F.Sc (Mariculture)

College of Fisheries Science,Veraval

Gujarat, India




Content



Sr. no

Title

Page no.

1

Introduction


1

2

Resources and distribution


1

3

Taxonomic classification


2

4

Biology


2

5

Growth


3

6

Reproduction


4

7

Larval development of mussels


4

8

Technology of mussel farming


4

9

Culture methods


5

10

Present status of Mussel culture in different countries


9

11

Culture of mussel in different states of India


10

12

Major areas of Mussel culture in India


11

12

Constraints


13

13

Prospects


13

14

Summary


13

15

Reference


16




1. Introduction


Culture of edible molluscs is now recognized as an effective way of enhancing food production and sea mussels among all the known cultivable organisms, give the highest production rate for two reasons: (1) they feed directly on the primary producers namely the phytoplankton and (2) it is farmed three dimensionally in the water column at the farm site. The world mussel production during 2006 was 1.89 million tons valued at 1.2 billion US dollars (FAO, 2008). The world production of Perna viridis during 2006 was 305,321 tons valued at 2.74 million US dollars. The total production of green mussels in India (2008) is about 15,000 tons (CMFRI, 2009). China ranks first in the production of cultured mussels in the world, followed by Spain, Italy, Netherlands, Denmark and France.


2. Resources and distribution


The green mussel Perna viridis and the brown mussel P. indica are the two species occurring along the Indian Coasts. The green mussel enjoys a wider distribution along the east and west coasts of India, including the Andaman Islands, whereas the brown. mussel is restricted to the southwest coast of India. Along the east coast, the green mussel is found onsmall beds in Chilka Lake, Kakinada, Madras,Pondicherry, Cuddalore and Porto Novo and alongthe west coast it forms on extensive beds aroundQuilon, Alleppey, Cochin, Calicut to Kasargod, Mangalore, Karwar, Goa, Bhatia Creek, Malvan and the Gulf of Kutch (CMFRI, 2000). Regular fishery for the green mussel exists in the region from Calicut to Kasargod and for brown mussel from Quilon to Kanyakumari along the Kerala Coast.


The green mussel perna viridishas a wider distribution occurring all along the Indian coasts. On the southwest coast of Kerala from Varkalai, South of Quilon and on the Kanyakuirari and southern Tinnevely coasts. In Maharashtra State, Ratnagiri, Malwan and Bombay has also wider distribution of P. viridis. In Mysore State, around Karwar, mussels are found in Kurmgad Islands in Karwar Bay. In the South Kanara section of Mysore coast.


It is along the Kerala coast the mussel fishery has attained a high significance because of the presence of extensive beds and the culinary preference of the people for the mussel. From Kasargod in the north to Varkalai Cliffs near Quilon in the south the green mussel is profusely distributed in all the rocky areas, the most important mussel centres being in the northern section from Cannanore to Calicut. Along the Madras Coast the brown mussel occurs from Colachel to Cape Comorin at Kodimunai, Vanikudi, Kurumpanai, Enayam, Enayam-Puthenthvrai, Ranranlhurai, Kadiapatnam, Colachel, Muttom and Kovalam (near Kanyakumari). In Andhra Pradesh, Kakinada appears to be the only Centre where mussel beds exist. In the Kakinada Upputeru for about 1.5 km along the creek mussels are observed. The green mussel is locally known as "Aalichippalu". In Orissa and West Bengal States no mussel fishery has been reported as the coast is sandy for the most part.


3. Taxonomic classification


Kingdom:

Animalia

Phylum:

Mollusca

Class:

Bivalvia

Subclass:

Pteriomorphia

Order:

Mytiloida

Family:

Mytilidae

Genus:

Perna

Species:

viridis


4. Biology

Mussels are sedentary animals with elongate, equivalved and in equilateral shells. The two valves are hinged at the anterior end with terminal umbo. External colour of the shell is green in P.viridis and dark brown in P. indica. Interior of the shell is margaritaceous and shining, muscle scar deeply impressed. Foot is finger-shaped, thick and extensible. Byssus threads emanate from the byssus stem and threads are long, thick, strong with a well developed attachment disc at their distal end. The mussels can discard the byssus threads and secrete new ones for enabling it to change its position. Phytoplankton forms the food of mussels and like oysters they are filter feeders.


Fig. Anatomy of mussel



Identifying character of Indian green and brown mussels


Characters


P. viridis (green mussel)

P. indica (brown mussel)

External colour


Green

Dark brown

Mantle margin colour


Yellowish green

Brown

Ventral shell margin


Highly concave

Almost straight

Middle dorsal margin

accurate

A distinct dorsal angle or hump present

Anterior end of shell


Pointed beak down turned

Pointed and straight

No. and size of hinge teeth

2 small teeth on the left valve and one on the right valve

One large tooth on the left valve and a corresponding depression on the right valve




Fig. green mussel (P. viridis)





Fig. brown mussel (P. indica)


5. Growth


P. viridis grows to 63 mm in 6 months, 91.5 mm in one year 117 mm in 2 years, 129 mm in 3 years and 135 mm in 4 years at Kakinada. At Ermore Backwater, green mussels have grown to 64 mm in 8 months. At Kovalam near Madras, mussel seeds of 13.6 mm have grown to 52 mm in 3 months and 25-30 mm to 70-75 mm in 3Vi months when grown in ropes suspended from rafts. At Muthukad 26.6 mm green mussels have grown to 52.4 mm in 6 months when grown on poles and 47.9 mm when grown in nylon webbing. At Calicut 23.6 mm mussels have grown to 88.2mm in 5 months when grown in ropes suspended from rafts and 66.9 mm in the natural bed. In the Binage Bay, Karwar 17.5 mm mussels reached 62.6 mm with an 4Vi months in culture rafts. At Ratnagiri 8 mm spat have grown to 61 mm in 7 months. At Goa, in natural bed, mussels have grown to 96 mm, 132 mm and 156 mm in 1-3 years respectively. Cultured mussels reached marketable size of 60-64 mm within 5 months and in 11 months they reached 85 mm. P. indica of 20 mm have reached 55 mm in one year when grown in ropes suspended from rafts in Vizhinjam Bay. The cultured mussels usually grow faster than those in natural bed and growth is comparatively faster in the open sea when compared to the Vizhinjam Bay.


6. Reproduction


In mussels sexes are separate and reproduction and larval development are similar to that of edible oysters. The male gonad is creamy white and in females it is pink or reddish. The mussels attain maturity at very small lengths. The green mussel attains maturity at 15.5 to 28.0 mm. The peak spawning period of the green mussel at Kakinada is from January to May, at Madras and Goa year round, at Calicut August-October and at Ratnagiri June-September and February-March. At Vizhinjam brown mussel spawns from the end of May till September with peak in July-August.


7. Larval development of mussels


Release gonad material (sperm and eggs) into the water i.e external fertilization. The fertilized eggs develop into trochophore in 6-7 hrs. "D" shaped veliger in 20 hrs. Larvae are free swimming for 15-20 days. Locomotion is with the help of velum. As the larvae metamorphose, the pedal organ developes. On formation of this the pediveliger larvae look out for a suitable substratum to settle. The larvae attach to the substratum by means of the byssus. The metamorphosis takes place and the secretion begins. The young metamorphosed larvae (plantigrade) is generally called "Spat" the ability of the animal to regenerate the bysus is an advantage for transplanting the animal to new areas in mussel farming operation.


8. Technology of mussel farming


Seed collection and seeding


The major part of the seed required for farming is collected on ropes suspended from the rafts during the peak spawning period. The spat settled on ropes are allowed to grow to a length of 30-40 mm. These half grown mussels are collected and transplanted to fresh ropes to avoid overcrowding and help further rapid growth and fattening. Seed mussels are also collected from the natural mussel beds during low tide. A well experienced farmer collects up to 100 kg of seed in one tide. These seeds are wrapped around the ropes with a loosely woven synthetic netting, which is specially manufactured for Spanish mussel farming. The seeded length of the rope is 8-10 m and these ropes are suspended from rafts 60-70 cm apart. In the raft culture, the seeds reach harvestable size of 70-100 mm by 18-24 months in the temperate waters.


Mussel seeds are collected from the intertidal and submerged mussel beds after the peak spawning season (September-November). Normally an experienced person can easily collect 20- 30 kg of mussel in one hour. The average seed size for farming is 15-25 mm and 600 g seeds are required for seeding 1 m length of the rope. Synthetic and coir ropes of 15-20 mm diameter are suitable for growing mussels from the rafts. The seeds are placed around the rope and securely wraped with knitted cotton cloth. The seeded ropes are suspended from the rafts, 0.5-1 m apart, with the lower free end of the rope about 2 m above the sea bed. An optimum of 60 ropes, each having 6 m seeded length can be suspended from a raft of 6 x 6 m size. The seed mussels get attached to the ropes by means of freshly secreted byssus threads in two to three days and the cloth disintegrates in seawater within about 10 days. After the suspension of seeded ropes the mussel culture farm needs only minimum attention to see that the rafts are in good shape and the ropes with growing museels are hung properly.


spat collector nylon rope


Fig. spat collector nylon rope



spat collector pipes


Fig. spat collector pipes



Hatchery production of spat

The basic technology for production of spat of P. viridis has been developed by CMFRI at Madras and for P. indica at Vizhinjam. At Goa, the National Institute of Oceanography also has achieved spat production in the case of green mussel. So far large scale production of mussel spat in hatchery has not been tried in our country.


9. Culture methods

Methods currently used for culturing mussels in the tropical and temperate waters fall into four categories: (1) Off bottom culture, (2) On bottom culture.


  1. Off bottom culture


Mussel culture on ropes suspended from raft


This method has shown the greatest development in recent years and appears to offer the best prospects for future expansion. There are two basic types of suspended culture, fixed and floating rafts. Suspended culture from fixed rafts is usually practiced in bays or sheltered areas, where the depth is less than 4 m with very little tidal range. This method is being followed along the European Coasts of Mediterranean and Atlantic, including Spain, southern France, Yugoslavia and Italy. The fixed mussel raft or park is constructed on top of 200 concrete posts of 15 x 15 cm size and 7 m long, piled in 5 rows of 40 each, at a distance of 5 m. 2 m length of the posts are driven into the bottom, 4 m in water and 1 m above the water level. A framework is constructed on top of these posts using wooden beams of 20 x 10 cm size. Eucalyptus poles are nailed over the framework at an interval of 1-1.5 m for suspending the mussel ropes.

A commercial limit comprising 10 rafts, each measuring 8 x 8 m is considered. Each raft holds 100 ropes and the seeded portion in each rope is 6 m. The duration of the cultue is taken as six months and a single crop is envisaged during the course of a year since the sea conditions are not generally favourable for a second crop. Depreciation was calculated on annual basis and the recurring expenditure for the duration of the crop. In a three year period, the raft is operational for one-and-half years only; cheaper materials like bamboo/eucalyptus poles, and empty oil barrels instead of specially fabricated MS barrels as floats, would meet the requirement.

Mussel raft culture method


Long line culture


Longline culture of mussel is practised in shallow waters of 10-15 m depth. This method of culture can withstand the severe monsoon conditions in the west coast. A single longline consists of 60 m long horizontal HPD rope of 20 - 24 mm thickness, anchored at both the ends with 150 kg concrete blocks and a series of 100 It capacity barrels as floats fixed at 3 m intervals. Vertical lines of 6 m length seeded with mussel spat are hung at a distance of 75 cm between two floats in the main line. A longline unit of 60 x 60 m can accommodate 12 horizontal ropes and 920 to 1,000 vertical seeded ropes. The horizontal lines are intercormected using additional lines. Mussel farming trials were initiated in the Vizhinjam Bay by following the floating raft culture method in 1973 and later the experiments were shifted to the open sea. In 1975, experiments on culture of green mussel were initiated in the open sea at Calicut and Madras adopting the floating raft culture technique, which continued up to 1980. After successfully developing and demonstrating the technique and production potential at Calicut the programme was shifted to Karwar in 1980 to explore suitable sites for mussel farming, to do further developmental work and demonstrate the production potential along the Kamataka Coast. Concurrent to the above developments, the National Institute of Oceanography developed a research programme on mussel culture in Goa. The Konkan Krishi Vidyapeeth implemented a project on mussel culture at Ratnagiri. Several short term experiments on mussel culture have been carried out by some University departments also.


  1. On bottom culture


Sea bottom culture

This method is widely practiced in Holland, Netherlands, Denmark and Germany. The principle of sea bottom culture is the transfer of young or seed mussels from areas of great abundance, where growth is often poor owing to overcrowding, to areas of good growth and fattening. Government allows farmers to collect mussel seeds from public seed beds during certain specified periods. The wild seeds are gathered by special mechanised mussel boats, equipped with three or four powered dredges. Each dredge can be operated separately and one dredge load will bring 500-600 kg of mussel seeds. One boat can carry 5000-6000 kg mussel seeds. Seeds collected thus are transferred to private culture plots, leased to the individual farmers and allowed to grow at the bottom. The half grown mussels are later transferred to plots in deeper areas for further growth and fattening. Normally the seeds reach the harvestable size of 50-70 mm in 20-36 months.

sea bottom culture of mussel

Bouchot culture or pole culture

(Source: FAO, 1990)

Fig. sea bottom culture of mussel.


Pole culture or "Bouchot" culture

Culturing mussels on poles is mainly carried out in the extensive intertidal mud flats along the Atlantic Coast of France. Intially rows of poles called "bouchots" interwoven with branch-wood are placed in the deeper part of the intertidal zone to allow mussel spat to settle during the spawning season. When the spats grow slightly bigger they are transferred to "bouchots" placed in shallow areas in the same zone. Now-a-days "bouchot" used for collection of spat, are obsolete and forbidden since they cause silting. At present seed collection is carried on loosely woven cocoa fiber rope, 13 cm diameter and 3 m long, placed on fixed poles in the intertidal area near the natural mussel beds during spawning season. Spat settlement takes place in 2-3 weeks between rope stands. These ropes are removed and wound around oak poles, 15-20 cm thick, 5 m long and driven 2 m into the tidal flat. The mussels attain marketable size on the poles. Periodical thiiming of mussels from the poles is necessary to prevent overcrowding. The mussels attain harvestable size of 50-70 mm in 24-36 months.


sea bottom culture of mussel

(Source: FAO, 1990)

Fig. "Bouchot culture or pole culture"


Purification of mussels


Mussel is a sedentary bivalve growing attached to rocks or any other hard substratum in coastal waters by means of self secreted byssus threads. They are filter feeders and therefore at any given time their stomachs are likely to be loaded with mud/sand particles and bacteria. Hence depuration of mussels is very important. Legislation regarding sanitary requirements in marketing mussels can be classified into two groups. In most countries mussels can be marketed only when originating from clean waters, where regular analysis ensures that quality is maintained. However, in southern Europe (Spain and Italy) all mussels must be depurated, wherever they originate from. As a result there is less stringent enforcement as to water quality, where the mussels are grown. It is rather easy to purify mussels of bacterial pollution, because they cleanse themselves of this type of pollution bacteria if kept in clean filtered sea water for 24-48 hours. This treatment can also clean the mussels of mud and sand particles in the stomach.

The depuration process consists of three aspects: (1) pumping clear sea water into large storage tanks (2) sterilization of water using 2-3 ppm chlorine or 1-2 mg ozone/litre and (3)keeping mussels in sterilized water for 24-48 hours. Recently ozone is widely used for sterilization of water, as it is a powerful oxidizing agent capable of killing bacteria and viruses rapidly.


9. present status of Mussel culture in different countries


Present status of mussel culture in SPAIN

World leader of mussel culture with a production of 770,000 tonnes in 2005 (FAO, 2006). During the breeding season, April-September, seed collectors such as loosely woven and heavily tarred ropes, 12-15 cm diameter made of spart grass or nylon are lowered from the rafts used for growing mussels. 12 mm wooden spacers are used to avoid slipping down of mussels. The ropes are 10 m long and well above the bottom. In the event of failure of spat settlement seed collection from natural beds from rocky shores is resorted to. Seed mussels thus collected are tied around ropes in clumps using a fine, large-meshed rayon netting which disintegrates in a few days time leaving the mussel seed firmly attached to ropes. These ropes are then suspended from rafts floated over 'Rias' (sunken river beds). The growth here is fast. When the ropes become heavy, exceeding a certain limit, the mussels are thinned out and distributed over greater length of rope. The harvested mussels are sold to canneries or placed in purification tanks before export.


Present status of mussel Culture in NETHERLANDS

Mussel ProcessorsGovernment allows farmers to collect mussel seed from public seed beds during certain limited periods. The natural seed that settle at the bottom of the shallow sea-bed are gathered by special mechanical mussel boats with dredging arrangements. One dredge load will bring about 500 kg of mussels. At times 15,000 kg of mussel seed are landed per day. A mussel boat can hold up to 50,000 kg of seed mussels. Mussels collected thus are transferred to private plots leased out to individuals and allowed to grow at the bottom. The halfgrown mussels are later transplanted to plots for further growth and fattening. Thus the system is a semiculture. Total mussel production is about 150,000 tonnes in 2005. (FAO,2007)


Present status of mussel Culture in FRANCE

Initially, rows of poles called 'Bouchots', interwoven with branch-wood are placed in the intertidal zone to allow mussel seed to settle during breeding season. When the seed grow slightly bigger they are transferred to 'bouchots' placed somewhat higher in the same zone. Nowadays 'bouchots' are obsolete and forbidden since they cause silting. At present seed collection is carried on by supporting loosely woven cocoa fibre ropes, 13 mm diameter and 3 m long in the intertidal area near natural beds during May-July. Seed settlement takes place in 2 weeks time, between the rope strands. These ropes are removed and wrapped around Oak poles, 15-20 cm thick, 4 m long and driven 2 m into the ground. The mussels attain marketable size on the poles total mussel production is about 130,000 T in 2004 (FAO, 2007).


Present status of mussel Culture in ITALY

Mussel seed is collected from natural beds as well as by employing spat collectors. Seed collection from beds is done by scraping with the aid of 'raschiette' (sharp blade). The season of collection is from April - May and about 100-1000 kg are collected per day per boat of two persons. Special spat collector ropes 'filimbindo' of 25 mm diameter are also used. This consists of 3 intertwined strings of polythene hung horizontally in parks called 'Vivai', with the help of thin ropes. For a park of 40 x 25 m, 135 m long rope is used. Seeds which settle in January are removed by April-May and restrung in ropes to be hung in the park for further growth. Formerly ropes of sparto grass were used for twisting around clustered mussels. Now 'Netlon' netting is used. The net is closed with synthetic strings and hung from a horizontal rope in the park. These are called 'Pergolari'. A park of 1000 m carries 715 pergolari. These are periodically inspected and if found heavier the nets are cut into small sections of 1 m length and mussels transferred to thick gauze nets for further growth to marketable size. Periodically the mussels are exposed for 2 hr to kill larval fouling community settling on shells.


Present status of mussel Culture in PHILIPPINES

To collect mussel seed, extensive bamboo structures are erected in places with muddy bottom. Spat collection and growing are combined since no transplantation is done once spat settle down. The mussels grow to marketable size in 6 months time. Divers pull out the planted poles, strip them clean of grown mussels on board a boat. Well graded and cleaned, the stock is transported rapidly to market. Formerly 'wigwam' method using 8 long bamboo poles in a circle of 4 m dia. around a central pole and nailed together with short horizontal bamboo braces just above low water mark was followed using central pole as pivot. Slender bamboo poles were thus kept inside the frame. This was found unsuitable resulting in overcrowding of mussel and poor growth. This has been replaced now by 'stage' system of rectangular bamboo structures. Culture is done subtidally in sheltered sites. Bardach et al., (1972) report that mussel seed already settled are removed from their natural substrates and reattached for culture. Reattaching is accomplished by placing the seed in a 2 m x 1 m tray with a quantity of cultch of oyster shells or bamboo stakes. The tray is suspended on poles, submerged in water.

Oyster shells with attached mussels are strung in groups of five on No. 10 wires. Strings of shells are above 1 ra long provided with loops and spacers and are suspended from bamboo platforms. About 1000 strings can be suspended from a platform of 1 m X 10 m. Bamboo stakes used as cultch consists of the whole tip of spiny bamboo, five cm in diameter at base and 2 m long, but are placed in the tray so that only the upper half is exposed to the mussels. After attachment the bare half of the stakes is driven into the bay floor for growth.


10. Present status of Mussel Culture in INDIA


Mussel culture is fast becoming popular in the Malabar area since 1997 following the success achieved by CMFRI in rearing green mussel by rack culture in the backwaters and popularizing through involvement of progressive farmers who took up its culture in the backwaters and found it as profitable venture. As a result demands came from new entrepreneurs for training, and mussel farming spread from Kasaragod to Ponnani. Backwaters Mussel culture in Kerala was started first in Padanna and Cheruvattur Panchayats in Hosdurg Taluk of Kasaragod district. Later it was taken to Elathur in Calicut district and Vallikunnu and Ponnani in Malappuram district. Total mussel production in India is about 20,000 tonnes in 2009-10. (CMFRI, 2009-10). Initially the low cost technology developed by CMFRI was transferred to five groups with 15 to 21 members at Cheruvattur and Valiyaparamba and provided financial assistance through North Malabar Gramin Bank and Cheruvattur Farmers Co-operative Bank. A loan of Rs.2,60,200/- was provided with a subsidy component of 50%. These groups harvested 67.4 tonnes of mussels during May-June 1997. A portion of the harvested and shucked meat (2000-Kg) was sold to the Integrated Fisheries Project, Cochin at a rate Rs.45/kg. and the rest was sold in the domestic market. The groups could realize Rs.3,34,555/= from the harvest with a net profit of Rs.1,04,455/= within a period of 6 months.


Mussel farm in Padana (Kerala)


Fig. mussel farm in Padana (Kerala)


11. Culture of mussel in different states of India


Kerala

Two species of mussels, green mussel Perna viridisand brown mussel P. indicaare available in Indian coast and are exploited on commercial basis for edible purpose. P.viridishas got a wider distribution along Kerala, Karnataka, Goa, Maharashtra and also in Andamans. P.indicahas got restricted distribution in south west coast of India from Varkala to Kanyakumari. Kerala is considered as the 'mussel fishery zone' of India since extensive natural mussel leds are available in the Malabar Coast and exploitation is done from time immemorial. The total annual mussel production varies from 18432 t of which 80% is contributed by P.viridisfrom Northern Kerala (CMFRI, 2008). In early 70's the Central Marine Fisheries Research Institute, Kochi developed simple, eco-friendly farming techniques through experiments and demonstration trials in different parts of the country in the coastal waters and estuaries. Repeated demonstration with full participation of fisher folk has proved this technology successful and the farmer groups started adopting mussel farming in estuaries and coastal waters. This has become a successful group farming activity by Self Help Groups of Malabar coast with technical support from CMFRI, BFFDA, and financial assistance from Cooperative banks and other financial institutions. Adoption of the technology was easy since it was simple, low cost, requires no additional feed, ecofriendly, short culture period of 4-6 months and good market demand. The production of green mussel through farming was 2t in 1996 and this has reached 7500tin 2006 mainly through group farming activities in Kerala (CMFRI, 2008).

Experiments in Kerala by CMFRI, adopting rope culture of the green mussel and brown mussel at Vizhinjam (Trivandrum), Anthakaranazhi (Alappuzha) and Kasargod have succeeded in producing harvestable stocks in a period of 5 months to 8 months. Floating rafts of 6 X 6 m or 8 X 8 m fabricated out of Teak pole and Bamboo poles duly buoyed and anchored firmly are used for suspending culture ropes in the coastal seas at depth ranging from 5 - 15 m. Even though the technology was standardized during middle 70's, mariculture production of mussel is not yet popular due to various reasons.


Kovalam Bay (Tamil Nadu)

Mussel seed of size range 10-20 mm were collected at Ennore from concrete piles and large iron buoys used by Madras Electricity Supply and transported to Kovalam. The seed were removed with a sharp knife, cleaned of the fouling organisms and seeded to coir ropes with the help of a strip of knitted cotton cloth about 6 m long and 20 cm wide. The cleaned seed were uniformly spread at the rate of 0.5 kg/m along the rope which was placed over the cloth, the edges of the cloth tightly rolled and stitched all along the rope.

The rafts used at Kovalam were fabricated out of casuarina poles covering an area of 25 sq. m. Each raft was buoyed up with the help of sufficient number of diesel oil drums and anchored by 25 m long tested anchor chain using stalkless anchors weighing 60 kg each. The rafts were floated at depths ranging from 8 to 10 m.


Based on the percentage edibility values, mussels of size range 75 mm to 80 mm are harvestable. In the case of Kovalam each raft accommodating 50 ropes of 6 meter length produced about 2 tonnes of mussels in a period of 4 months (i.e. when the mussel reaches 75 to 80 mm)( K. RANGARAJAN, 2000).


Kakinada (Andhra Pradesh)

The temperature of the sea water off Vakalapudi near Kakinada varies from 26.0 to 30.5°C and the salinity from 23.2 to 34.88 %. Off Vakalapudi, near Kakinada, during a period of 5 months the mussels grew from 13-25 mm (mean 21.7 mm) to 53-70 mm (mean 66.6 mm). The increase in mean size was 44.9 mm giving an average growth of 9 mm per month. In the natural bed at Kakinada, the mussels were known to attain an average length of 63 mm in 6 months, 92.2 mm in 1 year, 117 mm in 2 years, 129 mm in 3 years and 135 mm in 4 years. Mussel seeds were kept in nylon cages (CMFRI, 2005)

At Kakinada, rafts were anchored in identical fashion at slightly shallower water in the open sea (5 m depth).

Although experiments are yet to be conducted by floating rafts over vast stretches to calculate the actual yields per hectare the values obtained from the experiments conducted now are encouraging. Comparable production figures in respect of Ennore estuarine conditions and in the Kakinada Bay could not be given due to farm management difficulties encountered during the period of culture.



12. Major areas of Mussel culture in India


  1. Kasaragod district (Kerala):

The culture is done in the Padanna backwater systems in the Hosdurg Taluk. Major producing areas are Thekkekad, Badakekad, Ori, Kavunchera, Valiyaparamba, Koyambaram, Padanna kadapuram and Madakkal. The total production from this area during this year is 11,000 tons (CMFRI, 2005)


  1. Cannanore district (Kerala):

Culture is restricted to Koduvalli and Dharmadom area. The total production is 1,900 ton (CMFRI, 2005).


  1. Malappuram district (Kerala):

TTC training was given to 45 trainees at Vallikunnu panchayat during September 1999 by CMFRI. Subsequently, during January 2001, training was imparted to 60 trainees of Malappuram district under the self-help group (SHG) training programme of the State fisheries Department. This training was conducted at Balathurithi. The total production from this area during this year is 1500 tons (CMFRI, 2005).


  1. Kozhikode district (Kerala):

Mussel culture is being done in the Korapuzha estuarine system. Initially training was imparted to 20 persons under the self-help group (SHG) training programme of the State fisheries Department. The total production is about 2,000 tons (CMFRI, 2005).


13. Constraints


1. Availability of seed:


The seeds required for culture is presently collected from traditional fishing areas and these are often causing conflicts between farmers and mussel fishermen. This year has seen more conflicts than previous years. Hence it is essential that additional spat collectors have to be established along the coast to ensure supply of seeds to the farmers.


2. Marketing:


The harvesting seasons of cultured mussels is mostly during April - May months and farmers are forced to sell their crop before the onset of monsoon to avoid mass mortality of mussels due to freshwater influx into the backwater system. At present only a few processing plants purchases cultured mussels from the farmers and as a result the local market is flooded with cultured mussels during these months resulting in a fall in the prices and thereby affecting the profitability of the operation.


3. Depuration system:


The main constraint in the export of cultured mussels is the lack of proper depuration techniques. Depuration plants are needed at regular intervals along the coast so as to depurate the cultured mussels for export processing.


4. Storage facility:


If sufficient cold storage facility is provided, cultured mussels can be depurated, shucked and stored not only for export market but also for local market throughout the year. This will increase the profitability of the culture operation.


5. Post harvest technology:


Value added products of longer shelf life need to be developed from mussel meat to increase the revenue realization from cultured mussels. Mussel fry, mussel pickle etc. are some of the best examples for value added products. More studies are needed to develop ethnic cuisines with longer shelf life.


6. Siltation of backwaters:


Some areas in the backwater system have very high siltation levels especially during rainy season. This often results in mortality of mussels in the farms. Hence scientific feasibility studies are required to demarcate potential culture sites. Silting of the bottoms where culture is done may induce a problem for the benthic communities located underneath. This should be solved by strong policies directed towards correct management of the fouling and silt accumulated by the hanging ropes.


14. Prospects:


1. Backwater mussel culture is a decade old phenomenon along the Malabar coast and opens immense potential for resource and employment generation among coastal communities especially women living below poverty line.


2. Mussel culture is a low investment activity with very good returns. If promoted properly, mussel farming can be used as a tool for women empowerment in the coastal areas and can stimulate a healthy socio economic development in the area.


3. Better post harvest technologies can develop attractive value added products. Since very good export markets are available for mussels, they can be taken up as a challenging opportunity by technicians and scientists.

4. In the western countries, mussel is considered as poor man's oyster. But in India, mussel can be considered as tool for the upliftment of the poor people living in the coastal areas especially along the Malabar Coast.


Summary:

The advantage of mussel culture in our waters when compared to the temperate region is that the rate of production here is very high. In European waters the seeds attain marketable size in a period of 12-36 months. Here it takes only 5-6 months, because of the high productivity of the tropical waters. The peak spawning season of green mussel along the west coast of India is from August to October and along the east coast it is May-July. Seed collection and seeding can be made during this period. The crop will be ready within 5-6 months and subsequently due to the monsoon the culture operations cannot be continued. If suitable modifications are made in the floating raft culture system to keep the farm structures in position even in monsoon conditions or by adopting the latest method of long line culture developed for open sea rough conditions, theoretically two crops are possible.

The mussel in the farm spawns continuously 2-3 months after their initial seeding and seeds for further farming will be available from the farm itself. During the peak spawning season profuse settlement of spat takes place in the presently heavily exploited area. While exploiting the larger mussels, these seed mussels which form clusters with the grown-up mussels are also removed. The catches along with the seed are normally brought to the shore, where they are sorted and the seeds are discarded. The seeds thus destroyed will be 20-30 times the number of the marketable mussels. During one season the number of seed thus destroyed can be staggering. If these seeds are utilized for suspended culture there will be multifold increase in the production of mussels. The immediate need is for a perspective planning for the development of mussel culture as an industry with the full realization of its potential. Government support and assistance from public financing institutions with an element of risk coverage in the initial stage would help the establishment and growth of the industry. Mussel culture, should at least, to begin with be viewed as social necessity with a bias on nutritional improvement of the people and employment potential. Later, if necessary, it can be oriented for export market.


15. Reference

Aypa, S.M. 1980. Factors affecting recovery and growth rate of transplanted mussels, Perna viridis (Linneus). Master Thesis submitted to U.P.

Bardach, J.E., J.H. Ryther, W.O. McLarney. 1972. Aquaculture: The Farming and Husbandry of freshwater and marine organisms. Wiley-Interscience, John Willy & Sons, Inc., New York.

Chen, F.Y. 1977. Preliminary observation on mussel culture in Singapore. ASEAN 77 FA. Eg A/ Doc. WB17.

Davy, F.B. and M. Graham. 1982. Bivalve culture in Asia and the Pacific. Proc. of a workshop held in Singapore, Feb. 16, 1982.

Glude, J.B., M.A. Steinberg and R.C. Stevens. 1982. The feasibility of oyster and mussel farming by municipal fishermen in the Philippines. Tech. Report, Seafarming-Philippines. FAO/SCSP TCP/PHI/8907(1).

Jenkins, K.J. 1976. Mussel cultivation in the Marlborough Sounds (New Zealand). N.Z. Fishing Industry Board, NZ.

Korringa, P. 1976. Economic aspects of mussel farming. Proc. FAO Tech. Conf. on Aquaculture held in Kyoto, Japan, 26 May - 2 June 1976.

Quake, D.B. 1980. Tropical Oysters: Culture and Methods, Ottawa, Ont. IDRC.

PCARR. 1977. Philippine Recommends for oysters and mussels. PCARR, Los Banos, Laguna.

Yap, W.G. 1978. Settlement preference of the brown mussel, Modiolus metcalfei and its implication on the aquaculture potential of the species. Fish. Res. Jour. of the Phil. 3(1).

SEAFDEC. 1977. Third Report of the Mussel Research Project.



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