ICAR Research Complex for GoaEla, Old Goa - 403402

Goa, India

Central Marine Fisheries Research InstituteP.O. Box: 1603

Cochin - 682014, Kerala, India

(Indian Council of Agricultural Research)October~ 2003

Technical Bulletin No.3October, 2003

MfiHUfiL 0"MUSSEL FfiRMI"G

~~ICAR

ICAR RESEARCH COMPLEX FOR GOAEla, Old Goa - 403 402

Goa, India

CENTRAL MARINE FISHERIES RESEARCH INSTITUTEP.O. Box: 1603

Cochin - 682014, Kerala, India

Published by :V. S. KorikanthimathDirectorICAR Research Complex for GoaEla, Old Goa - 403 402, India

GramsFaxPhone

Research, Velha Goa0832 - 22856490832 - 2285381, 2284678, 2284679 (0)0832 - 2284260 (R)director@icargoa.nic.in

In collaboration with:Central Marine Fisheries Research InstituteP.O. Box No. 1603,Cochin - 682014Kerala, India.

Text Prepared & Compiled by :K.K.AppukuttanP. K. AsokanSunil K. MohamedS. SubramanianK. George Joseph

Edited by :S. SubramanianP. K. Asokan

Technical Assistance:Sidharth K. MarathePranjali ThaliV.G.SurendranathanM.P. Sivadasan

Front Cover: Grown up mussels ready for harvest.Back Cover : 1. Mussel seeds in the intertidal laterite rocks.

2. Seeding of ropes.3. Mussel farming in backwaters.4. Arikadukke - traditional mussel cusuine of Malabar.

Printed at :Lokmanya ProcessCorlim, Ilhas, Goa - 403 110

1. INTRODUCTION

2. POTENTIAL FOR OYSTER AND MUSSEL CULTURE IN GOA

3. BIOLOGY OF GREEN MUSSEL

4. MUSSEL FISHERY IN INDIA

S. SITE SELECTION, SEEDING AND AVAILABILITY OF SEEDS

6. CULTURE OF MUSSEL

7. ECONOMICS OF MUSSEL CULTURE

8. DEPURATION

9. DIVERSIFIED PRODUCTS FROM MUSSEL MEAT

Chapter 1Introduction

Mussel farming has a long history that datesback to the thirteenth century. Mussels are farmedin many areas of the world with the most commonspecies cultured being the blue mussel, Mytilusedulis. The main producers of mussels are coun-tries such as China, Korea, Spain, The Netherlands,Denmark, France and New Zealand. In 1997, 1.1million tonnes of mussels were produced worldwide,with most production occurring in China (nearly400,000 tonnes). The Indian mussel industry is rela-tively small compared with world standards and in1997, the total Indian production of mussels was5937 tonnes.

In India, mussel culture is becoming popularin the Malabar area since last six years followingthe success achieved by CMFRI in rearing greenmussel in the backwaters. The simple methods em-ployed for mussel farming was transferred to pro-gressive farmers who took up mussel culture in thebackwaters. Soon they found the venture profit-able. Demands carne from new entrepreneurs fortraining and mussel farming spread from Kasaragodto Ponnani. From a total of 250 tonr.es of musselsharvested in 2000, the total harvest estimated forthe year 2002 is 800 tonnes.

Mussel culture in the backwaters of Keralawas first started in Padanna and CheruvatturPanchayats in Hosdurg Taluk of Kasaragod district.Later it was taken to Elathur in Calicut district andVallikunnu and Ponnani in Malappuram district.This has happened mainly due to the popularisationefforts by the CMFR Institute. This year thePadanna farmers go for the sixth harvest.

Initially this low cost technology of farmingwas transferred to five groups with 15 to 21 mem-bers at Cheruvattur and Valiyaparamba. Financialassistance was provided by the North MalabarGramin Bank and Cheruvattur Farmers Co-opera-tive Bank. They provided a loan of Rs.2,60,200/=for the implementation of the project with a sub-sidy component of 50% subsidy. These groups har-

vested 67.4 tonnes of mussels during May-June1997.A portion of the harvested and shucked meat(2000-Kg) was sold to the Integrated FisheriesProject, Cochin at a rate Rs.45 per Kg. The re-maining harvest was sold in the domestic market.The groups could realise Rs.3,34,555/= from theharvest with a net profit of Rs.l,04,455/= within aperiod of 6 months.

Production

The total green mussel production by capturefisheries from Malabar area was 6317 tonnes dur-ing 2001. The total production from culture was 400tonnes. This forms only 6.3 % of the total musselproduction from Malabar, which had increased from4.62 % during 1999.

The yields obtained during 1999 by thegroups and the numbers of ropes suspended aregiven below:

Sl. Hace Total No. of Yield/ropeNo. yeild ropes (Kg.)

(tonnes)1. KoyaniJram 22.75 700 32.52. Kayuthakadu 36.22 5W 40.243. KaVlillChira 25.2 5W 284. Parantharmdu 12.75 300 42.55. Badkekad 18.75 625 306. Qi 13.5 482 287. Thekkekadu 22 7(1) 29Total 151.75 4fG7 3289 (Av.)

During the year 2002, the numbers have dra-matically increased and the total production esti-mated is 750 tonnes. The total production fromMalabar is estimated at 800 tonnes. The number ofgroups and individuals engaged in mussel culturehas gone up dramatically and the total number isabout 75. An interesting to note that the number ofsingle holding has increased and most of them aremale members.

In Kasargod, the net operating profit rangedfrom Rs. 7,646/= in Kayambram to Rs. 16,413/= atBadkekad. The cost analysis of mussel culture atPadanna showed that the major cost was that ofNylon rope (34%), Bamboo (20%) and seed (20%).The other expenditres involved cloth (7%), construc-tion cost (5%), harvesting (4%), seeding (4%) andcoir rope (3%).

Constraints

1. Availability of seed

The seeds required for culture is presentlycollected from traditional fishing areas and theseare often causing conflicts between farmers andmussel fishermen. Hence it is essential that addi-tional spat collectors has to be established along thecoast to ensure supply of seeds to the farmers.

2. Marketing

The harvesting seasons of cultured mussels ismostly during April - May months and farmers areforced to sell their crop before the onset of mon-soon to avoid mass mortality of mussels due to fresh-water influx into the backwater system. At presentonly a few processing plants purchases culturedmussels from the farmers and as a result the localmarket are flooded with cultured mussels duringthese months resulting in fall in the prices andthereby affecting the profitability of the operation.

3. Depuration system

The main constraint in the export of culturedmussels is the lack of proper depuration techniques.Depuration plants are needed at regular intervalsalong the coast so as to depurate the cultured mus-sels for export processing.

4. Storage facility

If sufficient cold storage facility is provided,cultured mussels can be depurated, shucked andstored not only for export market but also for local

market throughout the year. This will increase theprofitability of the culture operation.

5. Post harvest technology

Value added products of longer shelf life needto be developed from mussel meat to increase therevenue realization from cultured mussels. Musselfry, mussel pickle etc. are some of the best examplesfor value added products. More studies are neededto develop ethnic cuisines with longer shelf life.

6. Siltation of backwaters

Some areas in the backwater system have veryhigh siltation levels especially during rainy season.This often results in mortality of mussels in thefarms. Hence scientific feasibility studies are re-quired to demarcate potential culture sites.

1. Backwater mussel culture is a recent phenom-enon along the Malabar coast and opens immensepotential for resource and employment generationamong coastal communities especially women liv-ing below poverty line.

2. Mussel culture is a low investment activity withvery good returns. If promoted properly, musselfarming can be used as a tool for women empow-erment in the coastal areas and can stimulate ahealthy socio-economic development in the area.

3. Better post harvest technologies can develop at-tractive value added products. Since very good ex-port markets are available for mussels, they can betaken up as a challenging opportunity by techniciansand scientists.

In the western countries, mussel is consideredas poor man's oyster. But in India, mussel can beconsidered as tool for the upliftment of the poorpeople living in the coastal areas especially alongthe Malabar Coast.

Manual on Mussel Farming

Chapter 2Potential for oyster and mussel culture in Goa

IntroductionGoa is a small maritime state and has a rea-

sonable scope for fisheries production, mainly frommarine capture and inland culture resources. It hasan equally good potential for production of fisher-ies processed products for both internal and ex-port markets. More than 90 per cent of the popu-lation are fish eaters. Though Goa's coastline of105 km forms only 1.25 per cent of the country'stotal of 8192 km, its recorded marine fish landingcontribution to the country's total ranges from 2.2to 3.8 per cent, over the last four years. Similarly,the quantity of fisheries exported from Goa is morethan 2.0 per cent of the total fisheries exported byIndia, contributing about Rs.35.00 crore (0.43%)to country's foreign exchange. However, there is alarge scope to increase the production and exportthrough scientific and planned strategy. The percapita fish consumption of Goa is 7.4 kg/day com-pared to the national average of 5.4 kg, as againstthe recommended average of 11.0 kg. Present lo-cal fish utilization pattern includes 81 percent fresh,9 percent dried, 5 per cent salted and 5 per centmanured. Due to the state's increasing tourism, fishprocessing industry and the fact that 90 per centof the population are fish eaters, Goa has a defi-nite export and internal markets, for fish and shell-fish varieties. The fish production of the Goa dur-ing the year 2000 is given below:

Fish Goa production Indian total % ofcatch (ton) (ton) total

Marine 62,113 28,33,848 2.19Inland 3,509 28,22,701 0.12Total 65.622 56,56,549 1.16

Water resource of GoaRivers

The nine rivers of Goa are Terekhol, Chapora,

Baga, Mandovi, Zuari, Sal, Saleri, Talpona andGaljibag of which Mandovi and Zuari are the mainones. The river courses add upto a total distanceof 250 km and with its tributaries, canals andcreeks form a network of 555 km of riverine sys-tem.

EstuariesThe tidal influence and seawater ingress es-

tablish long estuarine system in many rivers ofGoa. The total estuarine area is 13,157 ha. Ex-cepting June to September, when there is a heavyfreshwater discharge into the sea due to monsoonrains, salinity and tidal effects are very much pro-nounced and they can be felt as interior as 40 kmfrom the river mouth as in the case of Zuari river.In Chapora river, salinity intrusion o,ccurs up to _about 20 km. Mondovi has an estuary 5 km wideat the mouth region and 0.5 km upstream.Mandovi estuary is mostly sandy or muddy. Ma-jority of Mandovi riverine network is brackish.Zuari river has the largest estuarine mouth (7 kmwide) and mostly rocky substratum.

Based on the salinity gradient, substratum andwave action, the estuaries of Goa can be dividedinto: 1) Euryhaline zone towards the river mouthwith high salinity (30 - 35 ppt), strong wave ac-tion and rocky or sandy subs-tratum. 2) Polyhalinezone with moderate salinity (18 - 30 ppt), lesswave action, sandy or clayey substratum and man-grove vegetation and 3) Mesohaline zone in theinterior region with low salinity (5 - 18 ppt) andsilty clay substratum.

Mangrove, brackish waters and 'Khazan' inun-dations

Mangoves of Goa are associated mostly withriverine estuaries especially Mandovi, Zuari andthe Cumbarjua canal. Several tributaries of

Mandovi, viz. Mapusa, Nanora and Goa have intheir network, islands such as Chorao and Diwarand marshy swamps like Pilerne <;wamps. Manymudflats are also formed on ei ther side of the ri vercanals.

Brakishwater areas of Goa come to about 3500ha and they are closely associated with estuariesand mangroves. 'Khazan' lands are low-lying paddyfields along the rivers up to the high tide mark.Many of the Khazan lands are the reclaimed bedsof Mandovi and Zuari estuaries, protected fromthe rivers by embankments and water entry is regu-lated through sluice gates. There are about 18,500ha of Khazan lands in Goa. In about 12,000 ha,Kharifrice is cultivated during June to October.During the remaining period, they are inundatedwith saline water, rendering them unsuitable for ricecultivation when only fishery activities can be un-dertaken.

About 1000 tonnes of clams, mussels andoysters are harvested annually from the creeks,estuaries and backwaters of Goa. Dense clambeds of Meretrix casta occur in estuaries of Goa,especially in Zuari estuary. Meat of clams, musseland oysters, is available throughout the year and itis in great demand in the markets of Goa. Thewedge clam, Donax cuneata is abundant in thesandy backwaters especially near Colva and Baga.Of late, there is an abundant settlement of Pernaviridis in the rocky bottoms of estuaries and back-waters and thereby a rich natural fishery existsduring October to January.

About 20,000 fishermen are engaged in ma-rine fishing, who are di.)tt :buted in 3.380 house-holds situated in 61 villages of the five coastaltalukas of the state. Goa has about 50 landingcenters. About 25 per cent of the marine catchcome from traditional fishing while landings of threetalukas namely Marmugao, Salcete and Bardezcontribute 75 per cent of the total catch. A size-able number of fishermen hand pick the clams, oys-ters and mussel and sell them in the roadside andmarket. Farm produGed oysters and mussels can

have three types of markets. Goa being an impor-tant tourist destination and having a predominantlyfish eating population, the internal market for oys-ters and mussels will be sizeable. Goa has the lo-gistic advantage of being nearer to cosmopolitancities like Bombay, Pune and Bangalore and theintake capacity of the live oysters and mussels inthese cities, is enormous if properly promoted. Ifregula! availability of sizeable quantities of depu-rated oysters and mussels are ensured, the exportmarket demand can also be taken advantage of.

Export from Goa constitutes 2.01 per centof the national fisheries export total. Goa exportedaround lO,OOO ton, valued at Rs.35 crore, overthe last three years. Details of the export during1998 to 2000 are furnished below:

Aspect of 1998 1999 2000 % onexport Indian

total

Quantity 9,658 8,849 11,206 2.01(ton)

Value 36.55 27.92 34.91 0.43(Rs. in crore)

The above export from Goa can be furtherenhanced through diversified brackish water aquac-ulture production comprising of oyster, mussel,mud crab, etc.

Oyster and mussel culture will give these fish-ermen a lucrative self-employment opportunityparticularly during lean periods. Aquaculture inGoa is predominantly shrimp based. Oysters andmussels being the highest biomass producing spe-cies with good export markets and relatively dis-ease free, can be potential candidates for exportoriented aquaculture in Goa. As Goa is having manyshallow sea incursion, vast areas of estuaries, man-groves and about 100 shrimp farms, oyster andmussel culture can be taken up as an ecofriendlyactivity without adversely affecting the environ-ment or as biopurifiers in shrimp farms. Successof oyster and mussel culture in estuarine areas, ex-perienced in Kerala, Karnataka and Mahat:a'shfracan be emulated in Goa as well.

Chapter 3Biology of green mussel

PhylumClassOrderFamily

MolluscaBivalviaMytiloidaMytiloidae

Common name

Green mussel, Green lipped mussel, Greenmussel, Asian green mussel, sea mussel.

Distinguishing features

P. viridis is distinguished from the other twospecies of Perna, P.indica and P. canaliculus, byfew physical features Perna viridis begins its lifeas a juvenile with a green and blue-green shell thatdevelops brown patches as an adult Internally, theexhalent siphon and the inner surfaces of theinhalant aperture are outlined with a stripe darkerthan the variably patterned dark brown mantle ThisMytiloid is distinguished from all others of thegenus by having 30 instead of 28 diploidchromosomes. The native range of the green mus-sel is along the Indian coast and throughout theIndo-Pacific. Perna indica is distinguished from P.viridis and P. canaliculus by mantle margins linedwith enlarged sensory papillae. Young P.canaliculus has light colored zigzag markings onthe outer shell and is found only in New Zealand.

Distribution

Perna viridis occurs naturally and is widelydistributed along the intertidal coasts of India Thegreen mussel is also local to Malaysia. P. viridis isbroadly distributed in the Indo-Pacific where itranges west from the Persian Gulf and east to NewGuinea and Japan and New Guinea for north andsouth ranges, respectively.

To adjust to the high sediment content in thewater the mussel has adopted an efficient way tofilter out the sediments using only the finest food

particles for energy requirements.

This advantage is gained through the use oflabial palps that extend through half of the mantlecavity and capable of producing strong ciliarycurrents. The ability of the mussel to dispose of thesedimentary particles is directly related to thecopious amounts of mucous produced by themussel. P. viridis to have a high organic retentionefficiency that may be related to the internalmorphology of the bi val ve.

Reproduction and growth

Sexes in this species is separate and thefertilization is external. Spawning is closely relatedto the monsoon seasons and occurs twice a yearduring March and April and October andNovember. It is most prevalent during southwestmonsoon rainfall. However, green mussels locatedin Thailand and in the Philippines exhibitcontinuous breeding throughout the year. Sexualmaturity typically occurs at 15-30 mm shell length(corresponding to 2-3 months). The life span ofP.viridis is typically 2-3 years. Growth rates areinfluenced by environmental factors such astemperature, food availability and watermovements. First year growth rates vary betweenlocations and range from 49.7 mm/yr in Honk Kongto 120 mm/yr in India. Average growth rate permonth for P.viridis ranges from 2.3 mm reportedfrom Hong Kong to 10.6 mm from Singapore.

Larval development

Spawning is initiated by either sex of the greenmussel with each releasing two streams of gametesinto the water. Spawning has also been induced bythe presence of other spawning individuals in thearea and a drop in salinity. Females release about 5lakh eggs. Seven to eight hours after fertilization,the zygote is completely transformed into mobile,trochophore larvae. After 16 to 19 hours theveliger larval stage is reached with the larval shellcovering the internal body parts and developing a

strong ciliated velum. The straight hinge D shapedlarvae metamorphoses to pediveliger with a pedalorgan, the functional foot and clescends to thebottom. The larvae completely metamorphosize ineight to twelve days. In 10-12 days the larvaesecrete the initial byssal threads and attachesitself. Changes in organ system takes place and thepost larvae with characteristics of adult musselcalled spat are formed. The mussel starts lookingfor a suitable foundation to attach itself to. The larvaexamines the different surfaces it meets and whenit finds a suitable surface, it attaches itself with afew byssus threads. This method of anchoring issecreted from a byssus gland and is used the wholeof its life span. The more the mussel is exposed towaves and currents, the more byssus threads itdevelops. If the mussel should need to move, it cutsoff its threads and develops new later. Pernaviridis has the greatest growth rate of the musselsstudied to date. Maximum growth of the greenmussel occurs 2m below the surface because of theincreased productivity of the water at that depthand a narrow area of temperature and salinityfluctuation.

Feeding

Perna viridis is a ciliary-mucoid filter feeder.This species is an efficient filter feeder, feeding

on small zooplankton, phytoplankton and othersuspended fine organic material. The four rows ofgills serve both as respiratory organs and filterfeeding apparatus.

Parasite

An unidentified adult digenetic trematode, ofthe genus Gorgoderina, has been found in thismussel.

Salinity tolerance

The high growth rate of the green mussel isrelated to high salinity and an abundance ofphytoplankton. Mussel has a 50% salinity tolerancebetween 24 and 80 ppt. The green mussel has ahigh tolerance for reduced salinities, increasedsurvival during atmospheric exposure, and highsurvival rates in turbid water. Salinity below 5 pptis lethal to Perna viridis if exposure exceeds 2days.

Temperature tolerance

The growth is significantly affected by tem-perature. 50% survival at lOoC and 35°C has beenreported.

Chapter 4Mussel fishery in India

The green mussel Perna viridis and brownmussel Perna indica are available in India. Greenmussel is widely distributed and found extensivelyaround Kollam, Alapuzha, Kozhikode, Kannur andKasargod in Kerala and in small beds in Chilka lake,Vissakhapatnam, Kakinada, Chennai, Pondicherry,Caddalore, Mangalore, Karwar, Goa, Ratnagiri andin Gulf of Kutch. Brown mussel has a restricteddistribution and is found along the southwest coastfrom Varkala to Kanyakumari and on southeast costfrom Kanyakumari to Thiruchendur.

Mussels occur in the intertidal zone attachedto rocks and other substratum. Brown mussels areseen upto a depth of 10 m while green mussel areavailable up to a depth of 15 meters. Mussels arecollected during September to May. Method offishing is simple. During low tide fishermen collectmussseis from the subtidal areas using chisel, knifeetc. They usually prefer to collect when water isclear and the day is sunny. Bags of coil' or nylonnetting are tied around their waist to stock thecollect mussels. In some places, two or threefishermen set out for mussel fishing in woodencanoes during low tide. About 60 - 160 mm is thesize range of the green mussel usually collected.

ProductionAccording to FAO of the United Nations, the

average world mussel production from 1991-1997is about 1.3 million tons. During 1997, China themajor producer landed abOl..t 400,000 MT, followedby Spain (190,000 tonnes) and Italy (124,400tonnes). The other mussel producing countries areNetherlands, Denmark and Korea Republic. Unlikeother resource, the cultured mussel far exceeds theproduction from the wild stocks and the recentproduction enhancement is mainly from mariculture.

In India, the green mussel is mainly landedfrom Malabar area. Chaliyam/South beach is thebiggest landing centre. This is followed byThalasseri, Moodadi, Kollam and Koduvalli.Seasonal fishery from Caddalore, Malpe,

Someshwar and Karwar is done mainly by mussel fisher of Mala bar areas.

Mussel fishery is a part time occupation tosome fishermen. A fairly good number of fishermenare engaged full-time in mussel fishing during thepeak season. About 520 fishermen are engagedfulltime in the mussel fishery in Trivandrum regionand about '270 fishermen are engaged part-time inthis occupation. The annual fishery here is around5000 tonnes. In the Malabar area, most of themussel pickers hail from Elathur. They migrate toother places during the season wherever thefishery exists. Some of the local fishermen also havestanco mussel picking. The total number ofmussel fishers in Malabar area is 1055. Thenumber of mussel divers in the mussel pickingcentres is given below.

Mussel fishers in the landing centres ofMalabar area.

Area Number of mussel fishersElathur 300

Chaliyam 250Chombala 100Thalasseri 80Thikkodi 75Koduvalli 55

South Beach 50Moodadi 50

Thalai 50Mahe 35

Kollam 10Total 1055---

In Chombala and Chaliyam, the mussel pick-ers use dugout canoes. Only one person uses theseboats. At Elathur plank built boats in which 4-5 per-sons go for mussel picking. They use outboard en-gines. They are the most professional among themussel pickers. Mussels are picked with the helpof a small chisel. Meshed bags of nylon are tied tothe waist for collecting the mussel.

In Elathur area, hand picking during low tideis also observed. This is practiced only forsubsistence and for a short period as long as themussels are present.

SeasonBulk of the landing takes place takes place

during October to April with peaks duringNovember and March. During the active monsoonperiod from June to August, the fishery is suspendedas the waters become turbid with low visibility andthe sea is also rough. Only handpicking in intertidalareas is done during this period.

UtilisationMussel flesh is popularly eaten, even

considered a delicious item of food by the peopleof West Coast. The mussels are mainly consumedin Malabar without depuration. The mussel aremainly cooked or fried. The mussels are sold withshell-on or shucked. The shucked meat is sold inpackets of '12 or 1 Kg. Packets. The shell on musselis sold either by weight or numbers. The cost ofshucked meat is about Rs.60 to 70 per Kg. The shellon mussel is sold at Rs 8-10 per Kg and Rs. 60-70per 100 Nos. depending upon the size.

Chapter 5Site selection, seeding and availability of seeds

Open sea and estuarine areas free from strongwaves action may be selected for sea farming.Clear seawater with high plankton production i~ideal for mussels. Moderate water current willbring the required planktonic food and wi II carryaway the waste materials. Silt wi 11 adverselyaffect mussel growth and survival. Site selectedshould be free from industrial pollution. Salinityrange of 30 - 35 ppt is ideal for both green andbrown mussel seafarming.

In shallow waters in the sea and estuary, rackand ren method can be adopted but for deeperregions in the sea, the raft method wi III be ideal

Seed collection and seeding of ropes

Healthy seeds from the natural beds are tobe collected for seeding. The site selected forcollection of seed should be free from pollutants.Seed collected from the submerged (sub tidal)areas will be healthier. After removing otherorganisms and weeds, the seeds may be washedthoroughly in seawater. Ideal size of seed is20 -25 mm. About 500 to 750 g of seed will berequired for seeding on one-meter length of rope.The length of rope is decided by considering the depthwhere the raft/rack is positioned. Whilesuspending the seeded rope on rack it must be tiedin such a way that the upper portion of the ropeshould not get exposed during low tide.

Nylon rope of 12-14 mm or 15-20 mm coirrope can be used for seeding. Old cotton net,cotton mosquito net or cheap cotton cloth etc. isused for covering the seeds around the rope.Cotton netting of required width and length isspread over it. After placing the rope over the

"eed, the net is tightly stitched in such a way thatthe seeds spread uniformly around the rope.

To avoid slipping of the mussels due togrowth, a 4 mm nylon rope is wound around the12-14mm seeded rope with knots at a distance of2S cm before seeding. Placing split bamboo pegsin the rope at intervals will also serve the purpose.Cotton net around the seed will disintegrate in aweek's time. The seed will secrete byssus threadsand will attach itself to the rope within this period.

A survey of the rich natural beds of greenmussels from intertidal to zone up to 15m depthwas conducted in the Malabar area. Spat settlementwas observed from July onwards. However, thearea becomes congenial for spat collection fromSeptember onwards. Mussel spat settlement wasobserved in granite and laterite formations alongthe entire coast lone. Granite rocks were seen inMahe. Kottikulam, and Chembarika (Kasargodedistrict) areas. The rest were laterite formations.

Estimated extent of mussel beds fromMalappuram to Kasargode district was about6,200,000 sq m (Table 1). Of the four coastaldistrict, Kozhikode has the highest seed biomassforming 68% of the total seed resource, followedby Kasargode (20.24%) and Kannur (9.8%)districts. However there was no significant seedsettlement in Malappuram district.

The total biomass estimated for Malabar areais about 8221 tonnes. In kozhikode district,Moodadi/ Thikkodi area has about 2400,000 sqm of mussel bed contributing about 66% of themussel seed in Kozhikode. About 42% of the seedin Kannur district is from Thalassery/ Thalai area.

In Kasargode, significant resource is found inChembarika and Kottikulam areas near Bekel .

Maximum spat settlement per unit area wasobserved in Kottikulam and Chembarika area,where 4.56 and 3.79 kg per sq. m was recorded.In these areas, seeds were observed in intertidalarea only. In subtidal area, maximum biomass/sqm was observed in Thikkodi followed by Elathur

area. However, the quality of seed of subtidal areais better as the seed in inter tidal area showedstunted growth.

Analysis of spat fall and spat length data showsthat monsoon conditions prevailing during themonths of July and August triggers spawning.Period starts from late July and continuous up toAugust end.

Zone Location area Estimated Average Estimated Average Number ofextend of Mussel biomass SIze of seed per kgmussel bed biomass in tonnes mussel seed(sq.m) per sq m (mm)

(g)KozhikodeChali yarn/South 800,000 820 656 16.19 2284BeachElathur/Kollam 750,000 1068 801 17.7 1314Moodadi/Thikkodi 2,400,000 1547 3712.8 20.66 1010Chombala 400,000 975 390 18.21 1381Mahe 200,000 1075 215 17.95 1328KannurThalassery/Thalai 500,000 680 340 17.7 1510Koduvally 500,000 625 312.5 18.76 1583Kadalai 250,000 575 143.75 18.34 1788KasargodeChembarika 225,000 3786 851.85 17.25 1788Kottikulam 175,000 4560 798 16.09 2325Total! Average 6,200,000 1239 8220.90 17.885 1631

Chapter 6Culture of mussel

Aquaculture originated in China over 4000years ago. Egyptian tombs dating from 2500 BCdepicted tilapia culture and by 2000 BC Japan wasrearing oysters. The first authentic study on aquac-ulture was written in 475 BC by Fan Li, entitledYang Yu Treatise on Fish Breeding, which discussescarp spawning in captivity. By the middle ages,Europe had also established farming practices. InEurope and Asia, mussel farming has had a historyof using bottom culture methods characterized byletting the mussel attach to sticks, poles, and ropes.The Dutch however, developed a bottom culturemethod much like land farming principles wheremussel seeds are dispersed on the bottom and sev-eral years later they are harvested. In Spain mus-sel farming is practiced based on suspended ropeculture techniques from rafts. Mussel farming hastwo distinct stages: spat collection and grow-out.Suitable measures that take into consideration thespecific needs of the mussels during the two stageswill result in the optimization of yield and thus bet-ter utilization of investment. A mussel farm needsan area that is pollution free as they easily absorbpoisons and pollutants. The same area should alsohave adequate protection against large waves. Evenif an area in the outer archipelagos usually means asecure source of nutrients and fewer pollutants.

Many culture techniques are used for grow-ing mussels worldwide. Some of these are describedbelow:

In Europe, mussel culture is believed to startedIn 1235, when an Irish sailor survived a shipwreckon the Atlantic coast of France. He found that thepoles he had kept for trapping birds attracted mus-sel spat settlement. This is became the basis forBouchot method which is the oldest and the mainmethod utilised in France. In this method, ropes withspat attached are wound around large vertical poles

(bouchots) in the intertidal zone. A mesh netting isused to cover the mussels to prevent them beingdetached and lost. A barrier is placed at the bottomof the pole to prevent predators such as crabs fromreaching the mussels. This method of culture re-quires large tidal ranges, in order to supply thedensely packed mussels with food.

This method is widely used in Netherland~.Denmark and Germany. The culture is based on theprinciple of transferring seeds from areas of greatabundance where growth is poor to culture plots inlower density to obtain better growth and fatteningof the mussel. The culture plots must have a firmsubstratum and less of drifting sand and silt par-ticles. In Netherlands, the seeds are dredged fromWaddenzee. The seeds are layed in intertidal ar-eas to produce mussels with thick shells and strongadductor muscle. In the subtidal areas higher meatyield and thinner shells are produced fit for pro-cessing industry. The production is about 22 tonnesper acre. The whole process is highly mechanizedfrom collection of seeds to harvesting and market-mg.

This method is becoming very successful inopen sea mussel farming. A rope is stretched hori-zontally near the water surface and maintained 1-2m from the surface with buoys. Mussels are grownon vertical ropes known as 'droppers', which hangfrom the horizontal rope for a length of 4m. Musselseeds are collected from natural beds and trans-

planted onto the ropes into a continuous sock-likentton tube, which is approximately 17.5 cm in width.Small mussels stripped from the collection ropes areinserted. This cotton sock is then wound around thedropper. The mussels grow and attach to the ropesusing their byssal threads and the cotton sock slowlydisintegrates and falls away. The droppers areplaced a minimum of 0.5 m apart and have at least4 m of free space from the bottom. In deeper wa-ters the gap between the bottom of the Ii ne and thesea floor is greater. Anchor ropes extend from eachend of the horizontal rope to anchors buried in the'llud of the bottom. As the ropes are kept taut, thereis no movement around the anchor to disturb thebottom as occurs when boats are anchored.

The density at which mussels can be culturedon long lines could be about 300 per meter, but de-pends on the food availability, which varies fromsite to site. Mussels grown on longlines can becomesmothered by naturally settling juvenile mussels andother fouling organisams . For this reason, mostfarmers prefer to position their farms away fromheavy spat settlement areas to avoid layers of spatattaching to larger mussels.

lar to long line clliture in that the mussels are sus-pended on droppers but these are suspended

from the raft instead of the long lines. The raft it-self is anchored to the seabed removing the needfor several anchoring systems. Long line culturehowever, creates less of a visual impact, and thedroppers can be spaced farther apart to maximisethe use of the available phytoplankton. Raft cultureis more suited to areas of dense phytoplankton and

to smaller operations, as there is less scope formechanical harvesting. This method of culture isused in the Galician Bays in Spain, Saldahna Bay inSouth Africa but has been abandoned by the NewZealand industry in favour of long lines.

This is the simplest of the rope-web methodused for green mussel cultivation in India and Phil-ippines. The main purpose of the pole is to supportthe structure. In between these poles, ropes aresuspended either vertically or kept horizontallywhere the depth is a limitation.

This is the simplest of the rope-web methodused for green mussel cultivation in India and Phil-ippines. The main purpose of the pole is to sup-port the structure. In between these poles, ropesare suspended either vertically or kept horizon-tally where the depth is a limitation.

Mussel (Perna)2 species

Green and Brown

Seed (1S-30 mm)Collection

N a tu r a I bed san dintertidal areas

Hatcherytechnology

Developed but notcommercial

Rope culture(C om m ercial)

S yn th etic meshtubing"

(Experim ental)

RAFTeSxSme6x6meSxSm

e4-6monthsculture

eS-12Kg/m

LON G LIN Ee 20 me4-6 months

cultureel0 kg/m

production

RACKeSxSme4-6monthseS-l0Kg/m

production

• HARVEST• DEPURATION• PROCESSING

Chapter 7Economics of mussel culture

Fisherman can take up mussel culture as anowner operated enterprise profitably. Thetechnologically practical, cost effective musselfarming is a short-term venture and can be apart-time occupation for fishermen. Managementof the farms is rather simple. Hardly any diseaseproblem is met in the cultivation of mussels.

Materials required for the culture is readilyavailable even in rural markets. Major constraint

in the enterprise is the availability of the seedthroughout the year. Though technology for seedproduction is available in India, at present farmershave to collect seed from the natural bed, limitingthe cultivation in the season just following thebreeding of mussels. The economics feature of therack method in the estu&ry and the raft method inthe open sea are presented below on the currentmarket trend.

COST ESTIMATESMussel farming by Rack and Ren method in estuary

Area of rack 5 x 5 m (0.0025 ha)No. of seeded ropes 100 NosLength of seeding in each rope 1 mCulture period Upto 7 months (Noy - May)

ExpenditureItem Quantity Rate (Rs.) Amount (R!Capital CostBamboo poles 16 nos 125 2000Rope for rack construction 0.5 Kg 110 55Seeding rope 13 Kg 110 1430

Total 3485Recurring costCotton netting material 25 m 12 300Nylon rope for attaching sinkers and mussel 2 Kg 110 220Needles 10 nos 2 20Nylon rope for stitching 0.5 g 110 55Cost of mussel seeds 200 Kg 6 1200Canoe hiring charges 15 trips 100 1500*Labour for seeding 8 mandays 150 1200*

Marketing expenses 500Transportation of poles 350Transportation of seeds 200

Total 5545

Total financial outlay 9030* RS. 2700 will go back to the farmer, hence actual recurring cost will be Rs.2845

INCOME GENERATEDTotal yield (lOOm x 8.4 Kg) 840 10.50 8820Income realized 8820Net income (Rs.8820 - 5545) 3375

COST ESTIMATESMussel Farming by Raft method in Open Sea

Area of Raft 5 x 5 m (0.0025 ha) INo. of seeded ropes 50 NosLength of seeding in each rope 4 m (depth of site more than 5m)Culture eriod Upto 7 months (Nov - May)

EXPENDITUREItem Quantity Rate (Rs.) Amount (Rs.)Capital CostBamboo poles 16 nos 100 1600Rope for raft construction, 4mm 4Kg 110 440Floats (Diesel/FRP drums, 2001 cap.) 5 nos 400 2000Rope for tying floats, 8mm 1Kg 110 110Anchors (2 grapnel each 50 Kg" 2 granite) 4 nos 3100Anchor rope, 12 mm, 60 m 4.5 Kg 110 495Seeding rope 20 Kg 110 2200

Total 9945Recurring costCotton netting material 50m 12 600Nylon rope for stitching 0.5 Kg 110 55Needles,twines,basin 200Labour for fabrication of raft 3 mandays 150 450*Cost of mussel seeds 350 Kg 6 2100Canoe hiring charges 15 trips 100 1500*Labour for seeding 8 mandays 150 1200*Raft mooring charges 3 mandays 150 450*Labour for harvesting 3 mandays 150 450*

Marketing expense (& shucking carges) 7200Transportation of poles 350Transportation of seeds 200

Total 14955

Total financial outla 24900* Rs. 4050 will go back to the farmer; hence actual recurring cost will be Rs.2845

INCOME GENERATEDTotal yield (50 nos x 4m x 10Kg)Income realizedNet income (Rs.24000 -14955)

24000240009045

Chapter 8Depuration

Introduction

Bivalve farming, especially that of mussels andedible oysters, is becoming popular among maricul-ture entrepreneurs in Kerala as the shallow watersn~ar the coast or estuaries provide good environ-mental conditions for bivalve growth. Unfortunatelythese coastal waters are also the areas often sub-jected to pollution from different sources.Bivalsesbeing filter feeders can accumulate human patho-g~nic bacteria and viruses when grown in pollutedwaters.

The main drawback to increased production islack of an appropriate price structure and assuredmarket for the produce. The product is exportableif it meets basic quality and sanitation standards.Through export to western markets the farmers canget better price for their produce, thereby, increas-ing their profit margins. However, European Unionmarkets are very stringent about the quality of bi-valve products that they import from Asian mar-kets. To ascertain and maintain the quality of bi-valve products depuration is essential. Simple depu-ration can be achieved by starving the bivalves inclean and filtered seawater/ brackishwater for acertain period of time. More effective depurationcan be achieved by using disinfected water in thedepuration process.

Even a simple and small depuration unit wi 11be beyond the capabilities of the small-scale farm-ers, and hence, it is proposed to have depurationplants where bivalve farmers are concentrated, thusenabling the farmers to use it as a common facilityfor a price to be determined later.

Depuration process

1. Requirements

(a) The basic principle for controlled purifica

tion or depuration of bi val ve involves providingclean and purified seawater in tanks, wherebythe bivalve filter and pump such water for aperiod of 24 hours or more if required.

(b) Ideally a depuration plant should be 10

cated near the least polluted source of water inthe vicinity of bivalve farms. Also the physicalcharacteristics (salinity, temperature, dissolvedoxygen etc.) of the seawater used in the depu-ration plant should not be radically different fromthat of the bival ve faiming areas. Care shouldbe taken such that the level of dissolved oxygenshould not be allowed to drop below 2 mg/1.

the dimension (total capacity 60 m3 x 2) shouldbe constructed at a level above that of thedepuration tank to facilitate gravity flow intothe depuration tank (see figure). The waterto be used will be pumped from a bore well.

(d) The choices for disinfection of seawater

are chlorination, ozonation and UV light irra-diation. The latter two are expensive, andhence chlorination (@ 3 ppm) is the methodchosen for this project. After chlorinating for12 h, the water will be dechlorinated using vig-orous aeration and / or neutralization with So-dium thiosulphate for 12 h.

(e) Most depuration plants use flow through,

once through or fill and draw principles. It isproposed here to use the batch process (filland draw), wherein seawater is drawn fromthe supply treated with predetermined amountof disinfectant to reduce bacterial levels, storedfor a time, then pumped to the tank contai ningbivalves. The process will be repeated onceto ensure complete depuration (see flowchart).

(f) Each depuration unit will consist of one

concrete tanks of the size 18 x 1 x 1 m with agradient of 3% to hold bivalves (see figure).Bivalves will be placed in perforated plastic

trays of standard size. The trays in a singletier will be raised from the tank bottom withthe help of concrete blocks. The tank will havedrain plugs at the lower end to facilitate clean-ing and flushing. Four such depuration unitsare envisaged.

two cycles with one complete flushing for bothmussels and oysters (see flow chart). The unitwill have the capacity to hold 4 tonnes of mus-sels and 1 tonne of oysters per run. The wa-ter requirement per run will be 120 m3.

RawSeawater/Brackish water

HarvestedM ussels/ 0 ysters

Culling& Jet

washing

Processing&

Marketing

Chapter 9Diversified products from mussel meat

Vast changes are being witnessed the worldover in production and utilization of seafood. Anlmprecedented growth in demand is observed forconvenience food items like ready-to-cook orready-to-serve type products processed out of avariety of fish and shellfish. Diversification ofproducts with value-addition seems to be thecatchword. So much so, processing of diversifiedproducts from fish and shellfish together with theirsuccessful marketing in overseas as well as urbandomestic markets require upgradation oftechnology and subsequent value-addition. Theconspicuous change in the consumer demands canbe due to the increase in expendable income,increase in the number of working-women,awareness of the different types of products andthe minimum standards of hygiene and sanitation,increase in the general standard of Ii ving and theconvenience aad speed in kitchen work.

Green Mussel, Perna viridis (L), found inabundance along the rocky coastal belt, is animportant item of seafood for the people of MalabarRegion. During the major harvesting season thatspreads over September to May, fishermen engagethemselves in collecting the mussels from the wild.Mussel culture by advanced technologies developedby CMFRI has been instrumental in increasing theproduction of mussels. A number of mussel culturefarms have come to exist now. However, culturedmussels constitute only a very negligible part of thetotal production. Normally, the local populatiOn usesmussels in the fresh condition for preparation ofdifferent delicacies. Mussels are exported todifferent countries in the frozen condition. They arealso airlifted in the iced condition to the gulfcountries where mussels are in great demand.

A number of different products from musselmeat have been developed over the years. CentralInstitute of Fisheries Technology has beensuccessful in the development of dried and smoked

mussel meat, marinated mussel meat, mussel meatpickle, mussel meat chutney powder, cannedmussel meat, ready-to-serve fried mussel meat etc.However, it is seen that very few mussel productsare readily available to the consumer at the retailmarket. The latest in the line is the condiment-incorporated, ready-to-eat, fried mussel meat invacuum packaging for i.he domestic and exportmarket.

The mussel shells are composed of calciumcarbonate. The shells can be commercially exploitedto make lime. The mussel meat is highly nutritiousand consumed by people of all strata of life.

MoistureProteinFatGlycogenMinerals

80.00 %13.00 %1.50 %3.50 %1.50 %

The proximate composition shows the richnessof mussel meat as an edible food item. In most ofthe developed countries, mussels form a delicacy.It is usually consumed in the raw condition incombination with a sauce for seasoning or in theblanched (partially cooked) condition.

Processing and preservation

Sedentary mussels are filter feeders and theyfeed by filtering the water and taking in thenutrients. This peculiar feeding habit results in theretention of a lot of foreign particles like mud, sand,bacteria etc. in the intestine.

The bacterial profile of the mussel meat isgreatly influenced by the quality of the water aroundthe natural beds. If the water is polluted, thecondition will be reflected in the quality of the meat.The feeding habits of the organism result inconcentrating different types of bacteria in the meat.Microorganisms like Coliforms, including E. coli, andfaecal Streptococci are indicators of faecal

pollution. The presence of these types of bacteriain the meat is an indication that pathogenic bacterialike Salmonellae, Vibrio etc. also might be present.

Therefore, the microbiological quality of themussel meat often becomes one of great publichealth significance. However, studies have shownthat the bacterial load of mussel meat is much lowerthan that of clams.

Apart from bacterial contamination, it ispossible that high residual concentrations of heavymetals and other toxic substances like pesticidesalso might be encountered in the meat if themussels have been harvested from groundssurrounded by chemically polluted water bodies.

All these unwanted particles are likely to beharmful to the consumer and hence it is necessaryto remove the same before consumption. To ensurethe safety of mussel meat, the live mussels have tobe depurated first. The process of depurationconsists of storing the live mussels in clear and cleanseawater for a continuous period of 24 hours,whereby the intestines are flushed out. Themussels can be stored in large containers or tanks,which ensure a circulation of fresh, filteredseawater. No feed or nutrient is given during thatperiod. At this stage, chlorination of the seawateris not of any added advantage since the shellsremain closed if there is available chlorine. Themussels, after this treatment (starvation for 24hours), should be put in water chlorinated to a levelof 5ppm available chlorine for 2 hours to removeany further impurities. This depuration process isfound to reduce the bacterial load of the mussel meatby 90 %.

There are two methods of removing the meatfrom the shell. Raw meat can be shucked out witha clean knife from the live shell-on mussels, or theshell-on mussels can be steamed/cooked to open outthe shell and the meat taken out. In the latterprocess, the meat gets cooked and a part of thenutrients is also lost.

Different types of products can be preparedfrom the mussel meat thus separated. The meatshould then be blanched in 5% salt solution for 5minutes. This consists of boiling the meat and ismainly to enhance the shape and retain the keepingquality of the mussel meat.

Different products from mussel meat

Dried mussel meat

The blanched mussel meat (given as above) isdried in the sun by spreading on a clean surfaceuntil a moisture level of 10% is reached. Tunneldrier (electrically operated artificial drier) or solardrier can also be used. The dried product is packedin sealed polythene covers after cooling to roomtemperature. The product can be stored for 4 - 6months. The dried mussel meat can be re-hydratedby soaking in water and used for preparation ofvarious curries etc.

The blanched mussel meat is partialJy dried inthe sun for about one hour (to a moisture level of40-45%). The partially dried meat is then smokedin a smoke kiln for 30 minutes. Coconut husk andsawdust can be used as fuel for smoking. Thesmoked mussel is again dried until the moisture levelcomes down to 10%. The finished product is packedin polythene covers for storage. The product canbe stored for 4 months. The .smoked mussel meatcan be used for preparation of different dishes asin the case of dried mussel meat.

Mu,>sels are also frozen, individually or asblocks. Thi' i<; mainly for export to EEC countries.Frozen mussel meat is packed in consumer as wellas bulk packs. The mussels are also processed as'cooked' with the meat in single shell. Frozen freshmeat has a storage life of 40 weeks while iced (upto8 days) meat when frozen has 15 weeks' storagelife.

Some attempts have been made for thecanning of mussel meat. The method adopted forcanning mussel-meat is basically the same as theone employed for other, canned fishery products.The medium used is either 2 % brine or refinedgroundnut oil. The blanched meat is packed in 8 oz.(200g) round tin containers and hot 2 % brine with0.2 % citric acid, or refined oil, as the case may be,is added to net weight. The cans are sterilized at1150C for 45 minutes.

Mussel meat marinade

The marinade can be prepared by keeping the

cleaned, washed and blanched (by boiling the meatin 3 % brine for 5 minutes) mussel meat in a bathof 3 % acetic acid and 3 % salt. The mussels canbe preserved in this liquid medium for a period offour months. The acetic acid concentration of thefinished bath should not be less than 2.5 %. 1500ml of the bath will suffice 1000 g of meat. Thefinished marinade can be stored in airtight glassbottles, preferably, out of direct sunlight.

Citric acid and tartaric acid can be used asreplacement for acetic acid, provided, the pH of themedium is maintained at the desired level.Flavoring can be effected by adding different spiceslike pepper, clove, cardamom, cinnamon etc.

Ready-to-serve mussel meat products

Mussel meat chutney powder

The dried mussel meat is ground along withother ingredients and sieved to get a moderately finepowder. This is then used after mixing with therequired quantity of oil.

Dried mussel meat

Black gram dhal

Red chilly

Coriander

Asafoetida

Refined salt

500 g

500 g75 g

50 g

5 gTo taste

The dried mussel meat is roasted in a fryingpan without adding oil until it is golden brown incolor. All the other ingredients are also roastedseparately in the same way. The ingredients,except refined salt, are then ground to amoderately fine powder. Salt is added to taste andmixed thoroughly. Allow to cool, and store in dry,airtight glass bottles or polythene covers.

Mussels of smaller size are usually used forthe preparation of pickles. Bigger ones are cut intotwo.

Recipe

Mussel meat (blanched & cleaned)

Green chilly

Ginger (skinned & grated)

Garlic

1000 g

50 g

WOg100 g

Red chilly (powdered)

Turmeric (powdered)

Mustard (ground)

Curry leaves

Refined salt

Gingellyoil

Vinegar (1.5 % acetic acid)

50 g

5g

25 g

10 g100 g300 ml600 ml

The mussels are fried in gingelly oil till goldenbrown in color. This is kept aside. Garlic, ginger,green chilly and curry leaves (cut into small pieces)are fried in the oil, drained and kept aside. Red chillypowder, turmeric powder and ground mustard arewarmed in the same frying pan. All theseingredients are then mixed thoroughly and allowedto cool. When cold, add refined salt (to taste) andvinegar, and again mixed thoroughly and set asidefor two days for maturation.

Washed and dried glass bottles are rinsed witha small quantity of vinegar and the pickletransferred into them. Care must be taken to seethat air bubbles are excluded. Add a thin layer ofwarmed gingelly oil above the pickle and securewith an airtight stopper.

Condiment-incorporated fried mussel meat

This is a very tasty convenience product. Itkeeps well for a reasonably long duration whileretaining the taste and texture. Two permitted foodpreservatives are used for its preparation. Air andvacuum packing are possible; vacuum packingprovides better storage life.

Mussel meat is fried to a golden brown color.Condiments like chilly powder, turmeric powder,salt, pepper powder, and, the preservatives, Calciumpropionate and Sorbic acid, are added in thepermitted level.

Fried mussel meat

Red chilly powder

Turmeric powder

Pepper powder

Coriander powder

Refined salt

Calcium propionate

Sorbic acid

1000 g

30 g2g

2g

7.5 g20 g

3g2g

The condiments are warmed in a frying panover a low flame. The mussel meat, which hasalready been fried and set aside, is added to thewarmed condiment mixture and thoroughly mixed.Allow to cool down and pack in polythene covers.The product keeps good for three months. Thisproduct is easy to develop, has a good shelf life,can be stored at room temperature and is veryconvenient for use. Moreover the product does notrequire any sophisticated method or machinery.

Slightly modified method has since beendeveloped for the preparation of vacuum packedready-to-eat, fried mussel meat. The shell-onmussels are washed thoroughly in potable waterchlorinated to a level of 2 ppm. They are heated ina steam chamber and the meat shucked out. Themussel meat is cleaned by removing the intestinalcavity and washed. The meat is then fried usingrefined groundnut oil in an electric fryer for 6minutes. The temperature for frying is maintainedbetween 170 -180 C. The material is cooled andkept aside. The condiments are slightly warmed andmixed thoroughly with the fried mussel meat andkept overnight for equilibration of moisture. The

fried meat is then packed in 12 plain polyesterlaminated with 118 LD-HD co-extruded pouches(size: 12 em x 15 em).

The vacuum packed fried product keeps wellfor 9 months.

The proximate composition (%) of fresh andfried mussel meat

Parameter Fresh meat Fried meat

Moisture 76.69 5.25Fat 2.57 38.86Protein 12.55 43.20Ash 2.06 4.60

Diseases / Poisoning

Mussels are said to be harmful whenconsumed during periods of red tide. This mainlyoccurs when dinoflagellates bloom, excrete and dieoff. These algae produce a neurotoxin, which findsits way into the mussels. When human beingsconsume the contaminated mussel meat, theybecome affected by paralytic shellfish poisoning.

Desanding(Depuration)

Fresh LiveEnvisaged Oysters/mussels(Envisaged)

Heat Shucking

GradingCounts 150 - 300 / kg

Packing in

1 polybags

Icing FreezingI

Canning II SmokingI

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