The technique of raft culture of mussels developed and

practised in Spain and followed by other European nations is a stimulating example of the higher efficiency of resource use, technically feasible to achieve several-fold increase over the level of natural bed  production

Nayar, K Nagappan

CMFRI Digital Repository

CMFRI WORKSHOP ON MUSSEL FARMING 25 - 27 SEPTEMBER, 1980 MADRAS CENTRE OF ADVANCED STUDIES IN MARICULTURE CENTRAL MARINE FISHERIES RESEARCH INSTITUTE P. B. No. 1912, COCHIN-682 018, INDIA CENTRAL MARINE FISHERIES RESEARCH H£TITUTE COCHIN - 682 018 CENTHE OF ADVANCED STUDIES IN l".ARICULTURE WORKSHOP ON MUSSEL FARMING HADP.AS 25-27 SEPTEi'IBER 1980 --------------------------------------,----------------------, TECHNICAL SESSION I P~CSEl'JT STATUS OF, Ct'!FRI-CAS/NF/80/BP -3 I'lUSSEI, cumURE ' , -------------------------------------------------------------:PRESENT STATUS OF NUSSEL CULTUH.E IN I NDIA K. NAGAPFAN NAYAR Central Harine Fisheries Research Institute, Cochin - 18 INTRODUCTION The technique of raft culture of mussels developed and practised in Spain and followed by other European nations is a stimulating example of the higher efficiency of resource use, technically feasible to achieve several-fold increase over the level of natural bed ' production. This liiotivatod the efforts in India too to develop mussel production in a manner quite diffe-rent from the convent ional path in which we have I1iOved so far. This was all the more made easy since all along our coastal reg ions there are large unexploi ted or not yet fully ut ilised mussel population. Further, the I1lOst promising way of conver-tint'> iliarine phytoplankton into animal protein is to =lture shellfishes as they feed on products which are only one step ' down in the food chain. The great resilence, rallid growth and easy harvesting of nlUssels together with the additional plus factors in our waters with reg~rdsLabsence of pollution and Lto - 2 -high productivity of waters warranted the maricu1ture attempts on mussels. This culture attempt by CHFRI cot1l4enced less than a decade ago, in 1971 at Vizhinjam where seeds of the brown mussel Perna indica were collec-ted from nearby natural beds and seeded on to ropes of different lengths and suEp ended from rafts. Success was achieved by obtaining a five-fold greater production, in a shorter duration when compared to natural bed yield. This paved. way for extending the rap e cul tlire technique !for green mussel culture at Calicut and ;'1adras too' so as to evolve apjJropriate technique of culture depending on re -spective local conditions. The effort at Calicut was by and large a great success since the yield of gTeen mussel here was as much as eight times the seed weight in a very short period of 150 days. Several obstacles encountered -here and there during the course of farming experiments ar~ be ing studied and solved so that standardisation of techpiques . in all _,aspects can be done in a few years time from now. In addition to the work that is being done by CHFRI, attempts are also being made to study the various problems connecte'd wi til mussel culture by the Konkan Krishi Vigya"t peeth at hatnagiri and also by 'the National Institute of Oceano~ra"hY at Goa. The success obtai ned at Vizhinjam on mussel I culture helped the Fisheries Department of the Governnlent of Kerala to take up a Pilot Project on mussel culture at Vi~hinjam in 1975. JillVIEW OF Tl'E NUSSE[, CUI,TURE W CRK IN THS 'dEST A ~ID EAST cnAST I. West coast: a) Vizhinjam; Culture of the brown mussel 1"81'na iudicaat .... 3. - 3 -Vizh injam is a semi -culture in t he sense the seeds are collected from the na tural setting grounds and grown on floating r afts till they attain narketab l e size. The initia l experiments were conduct ed inside the bay area, wh ich is well ~rotected from the strong wave action during the monsoon s eason. Seeded ropes suspended from the rafts sho 'ded very bood growth. Based on int eresting preliminary results obta ined, a ttempts were made from 1978 onwares to carry out mussel cul ture in the open sea. RElfts of different . . sizes , r anging fl;'om 6 x 6 m Ito 10 x 10 m were fabrica ted with t eak and bamboo poles Iashed together by coir or nylon rope swerE! tried. Oil barrels of 200 litrecapacity treated with anticorrosive ~aint, were used as floats to give the requireq buoyancy for the rafts. The' r a fts were indivi-dua lly moored by anchors using the r equired length of anchor chain. In the bay area it was possible to keep the r aft in posit ion throughout the year, but in the open sea it was possible only during December to Hay when the sea is fairly calm. The experiments in tile open sea were carried out 1-2 kill away frcm shore at a depth of about 20 m. The brown mussel a t Vizhinjam area normally spawns during the month of Nay, prol ong:i.n€; t ill September. As it was found that s eed mussels of 20-35 mm size are better suited for seeding purposes, the collect ion of seed from the natural rocley ··be'ds i s best d one during September-Novelab c;r pe riod. Different types of Sp2. t collectors were also. . tried. ,inside the bay for . t he collection of spat. SpTii';~pes suspended from the r a fts gave good results. Seeding technique: The seeds were wrapped around coir or nylon rope and secured by cotton netting or bandae;e cloth. It was observed . ... 4 .. - 4 -that as the. seed attach well and grow on nylon ropes it will be more economical to use nylon ropes. For seeding purposes 1.4 to 2 kg of seed were used per meter len~th of ro~e . In the open s ea about 10 m. long rope were seeded depending on depth of the water. The seeded mussels suspended from the raft attach very soon to the rope and the outer cloth used for keeping them in position disintegrate. In the Bay area it was observed that the mussel s reach marketab le, size of 55-60 mm in a period of 8 months showing a rate of growth of 2.9 to 3 .5 rum fer month giving a meat value of 41~ at the time of harvest. In the open sea, 60-65 rum size was atta ined in 5 months and the rate of Isrowth was about 5.5 rum per month. It was also seen that the production was 10-12 kg of mussel per metre length of rope in the bay area in 7 months, whereas in the open sea it was 15 kg for a 5 month-period. (b) Calicut: L.ussel culture work is being done at Calicut for the past 5 years . The t echnology of culture of the green !hussel g.viridis that was being tried was basically the same as that of Vizhinjam with slight modifications to suit the local conditions . Hafts of surface area of 275 sq. meters were cloated in the open sea at a depth of 8 metres. hussei seed ( 10 to 20 nun size) collected from the local natural mussel beds were used for seeding ropes. These s eeded ropes were suspended from each raft and 750 gm~ of sfied were used p" r length of rope. Usua lly 7 ·nietre of rope was seeded since the depth where the rafts were moored was only 8 m. The mussels grew at the rate of 14 mID per month and attained a size of 85.5 mm in a period of 5 months. The rate of growth of the mussels- in the natural bed was slower being only 6.5nm per month. The initial average . .. ... 5. - 5 -weight of .85 gm/per mussel increased to 29 g . during this period. \Jhile harvestinb, an average weight of 8 2 kg of mussel was achieved on single rope thus showing an average production rate of 12.3 kg of mussel per metre of rope. Instead of each raft being separately anchored, a few of them were serially connected for easy management . Follow-ing the success of the experiments, a demonstration project was started in 1978. c) Goa: Work was initiated by the National Institute of Oceanography at Goa in April 1974 (Qasam et 13.1, 1977) and the raft method of culture was followed. Based on the eXr:eriments conducted it was observed that a raft of 2.5 x 2 .5 m could accommodate 40-60 DlUfJsel ropes of 3 m length with 2.5 ill seeded portion . The seeded mussels grew to a size of 85 mm in al l month period recording an average growth of 8 rom/month. In the natural bed at Goa it was observed to be only 5 mm/month . In the farm the haryestable size of 60-64 mID was attained in 5 months time. Based on the observation carried out for a ~iod of. 1 year from 2 rafts having about 120 ropes of mussels the economics have been worked out (Qasim et a l,op.cit) which gives a return of 181% of the capital amount within a period of one year . As most of the materials could be used again for another one or two years with slight expenditure on maintenance of the raft, it was assumed tha t the yield for the next two years would be much higher although the same has not been ment io-ned by them. Rao et 13.1 (1976) carried out experiments on spawning, fertiliza tion and larva l development of the green mussel at Goa . They were able to study the early develo:flIllenta 1 stages only up to the setting stage. Efforts .toaehieve COlilplete •••••• 6 • - 5 -weight of.85 gm/per mussel increased to 29 g. during this period. While harvestine;, an average weight of 82 kg of mussel was achieved on single rope thus showing an average production rate of 12.3 kg of mussel per metre of rope. Instead of each raft be ing separately anchored, a few. of them were serially connected for easy management. Follow-ill{;, the success of the experiments, a demonstration project was started in 1978. I c) Goa: Work was initiated by the National Institute of Oceanography at Goa in April 1974 (Qasam et aI, 1977) and the raft method of culture was followed. Based on the ex}'eriments conducted it was observed that a raft of 2.5 x 2 .5 m could accommodate 40-60 mU!Jsel ropes of 3 m length with 2.5 m seeded portion. 'The seeded mussels grew to a size of 85 mm in all month period recording an average growth of 8 mm/month. In the natural bed at Goa it was observed to be only 5 mm/month . In the farm the harvestable size of , . 60-64 mm was attained in 5 months time . Based on the observation carried out for a V" iod of 1 year from 2 refts having about 120 ropes of mussels the economics have been worked out (Qasim et ~l,op . cit) which gives a return of 181% of the capital amount within a period of one year. As most of the materials could be used again for another . one or two years with slight expenditure on maintenance of the raft, it was assumed that the yield for the next two years would be much higher although the same has not been ment io-ned by them. Rao et al (1976) ca rried out experiments on spawning, fertilization and larval development of the green mussel at Goa. They were able to s tudy the early developmental stages only up to the sett ing stage . Efforts tn aehieve complete ...... 6. - 6 -success up to spat settling stage and spat growth are ; a , necessary to evolve_sound seed production techniQue under controlled eondit ions. Attempts are be in::., made at ;fI' esent at Vadras am Vizhinjam by the CHFRI to perfect the hatchery techniQue vlhere some initial success has been achieved but the technology is yet to be po rfected. II. East coast : a) Hadras:' At Madras also the technology of green mussel culture is more or less the same as done at Calicut and Vizhinjam. This work was initiated by CMFRI in January 1973 at Znnore estuary Where the depth ' of water was about 2 m. Being a shallow area fixed rafts were constructed by means of wooden poles and mussel seed colEcted from the nearby natural beds were used in preparing the usual t)Te of mussel ropes and were suspended from the raft. Although the mussel seed got attached to the ropes and grow very well , within a short period the silting in that area appeared to 'be very heavy gradually reS\llting in tota l mortality of mussels in the farm, A growth r a te of 9 mID per month was observed. As the site ap~eared to be unsuitable for mussel culture, the work was shifted to Kovalam bay where the candi t ions appeared to be more favourable. At Kovalam instead of having fixed raft system the rafts were floated, by means of suitabl e oil barrels and moored by ?~chors and ~nchor chains. Seed were collected frolJl Kovalam natural beds and also from Ennore. The rate- ,of, growth at Kova 1B.lll appeared to be rapid and within a period of 4 months the mussels attained a J'llarketable size of 70-75 mm, registering a growth rate of 13 rnm/month. A raft with 50 ropes of 6 TIl length each gave a 2 ton production within a period of - 7 -4 months. As Madras coastal zone is a cyclone-prone area 'affecting the coast during Hay-June and or October-December, it was felt necessary to evolve a stable raft system like submersible rafts. Such r~fts with conical floa ts ere at present being tried, so that the rafts could withstand any type of rough s ea . , An atteLTpt was also 'ma de at Kovalam, Madras to follow ' BQuchot' method of Imussel culture (Stake culture on intertidal flats). But this method had to be abandoned as the posts could not be kept in position in the sea bed on account of wave action and int ense fouling. b) '4altair: Although attelll:;,..ts to culture green ulUssels were made a t 'daltair they did not give any encouraging results. The rafts which wer e floated there could not withstand the strong wave action most of the months with the result that there ha s been always difficulty in mooring the rafts in position. c) Tuticorin : During 1975 and 1976 experimental culture of mussels brought from Gape GOLlorin and Guddalore was attempted in the Harbour basin at Tuticorin by suspending se~ded ropes from 5 x 5 m r aft_ The growth wa s' poor and the seed ,falling off the ropes was one of the ma in problems . Even after 9-10 months the mussels did not attain sexua l ma turity and the meat content was very low '. It was thought the general paucity of , phytoplankton might be one of the controlling factors. The experiments ha d, to be discontinued as the area was considered unsuitable. Transplanting s eeds on granite boulders also met with little success since the lxerlation by perches like Gaterin sp. Teuthis_spp wiped out the stock • • • • • 8." Although different methods ',like bottom culture, bouchot culture, raft culture, rack culture and pole culture are being followed in different countries only 'raft culture' teChnique was tried in India considering the high yield known from this three d ilil,ens ionsl culture environment. In France, it takes 2 years for cultured mussels to reach the marketable size of 40-50 mIT!. In YUgoslavia it takes 15-18 months for the harvest size of 70 nun to be attained. ,Culture experiments at Calicut and Vizhinjam have shown that the green mussels reach 75 Illlt, size in less than 6 months and the brown mussels grow to 55-60 Illlll in 8 months. Comparatively t"is is a very rapid growth. The spanish raft systeJil cab yield 50-60 tons (Andrew, 1968) per raft which is a J1eery good produc-tion rate. But under Indian environmental conditions the indications are that the production may over-reach the achievement recorded in Spain. Per hectare production has been calculated to be as high as 450 tons at Caiicut. Heighed against these advontages Sallie of the difficulties and bottlenecks encountered during the course of experim'illts remain to be satisfacl;orily solved before culture industry can be, established on l~ofitable lines. The first of these concerns fabrication of an all~weather .- . . proof raft to stand aga:inst the furyofthelllOnsoon ,windS and wavee during June-AuguBt in the weBt coaBt and November-December in the east coast. Year after year rafts had been lost alongwith the growing stock of mussel because of this factor. To overcome this difficulty attempts are being made ..... 9. - 9 .-at Madras to find out the suitability of a sumbersible raft system floated at sub Slrface level. This can minimise the stress on the raft. An alternate method which is being thought of is the use of synthetic pliable poles for the raft frame work which will offer very littie resist€lnce to riding waves and swells • . Long-line cultUre, as is done for oysters in Japan , might also help to solve -the problem. But this reg.uires selection and identification of areas ylear of navigation and traditional fishing activities . This is yet to be a ttempted in India. I Problems of sewago.and industrial contamination in the coastal areas do not at present hold out serious prob-lems. But this has to be kept in view while future expan-sion is planned. Honitoring the environmental conditions and studying the physico-chemical characteristics of the. farm areas is a bsolutely essential to keep track of the changes in the CJ.Uality of water. liiussels can accumula.te fairly high concentration of metals like z,inc, copperf'B~rcury in the tissue. Though these are not l etha lto . the mussels, human consumptiol;l of ffiUl'"sel ne at in wh ich these are stored might , have serio1,ls·._ conseCJ.uences. Very often mussel seed f alloff the ropes due to some unknown reasons and studying the interaction of inviron-mental variabfes, mussel physiology and behaviour thus seems desirable to devise methods to avoid this. Problems of processing technology. and marketing are also to be properly studied and standardised; Pur.ifjc~{on of mussels after harvest appears fecs ible to reduce the . bacteria l iload. It is known tha t SOIlle bacterie- in 1he flesh ...•.. 10. i I , . - 10 -can survive prolonged refrigeration and under normal storage conditions may multiply also. The usual cooking methods may destroy some of the bacteria but thorough studies are needed to gain precise knowledge on the above aspects. I Sanitary control of mussel farr" area is aJ. so desirable for which regulations and norms are to be stipulated based on the above studies. Unlike oyster meat, mussel meat enjoys popularity amongst different sec·tions of Indian IS ople. Consumer preferencl" and deillands should be a scertained through 1I"!l.rket surveys. Extemion \'i"ing remains to be developed to populari-se mussel fnrming techniques among f isheruen and mussel eatinb habit among people who are not aware of the nutritio-nal richness of its meat. Creating a stable internal and export market depends on the standardisation of the quality of products end the cheapness of the lilateria l offered to the market. Priority attention should be given to efforts to achis"\I:e the above obj') cti ves . Althougb our culture experiments have established the feasibility of farl.d ing, the above problems are to be satisfactorily solved to put industry on economically viable lines. REFERENCES ANDREU, B. 1968. . Fishery and culture of mussels and oysters in Spain. Proc. ~. r101. 3: 835-46~ QASm, S.Z., A.H. PARULEKAR, S.N. HARKANTRA, Z.A. ANSARI AND AYYA}')"AN NAIR, 1977. Aquaculture of Green liussel Mytilus viridis L.: Cultivation on ro~es from floating rafts. Indian Journal of I'larine Soiences, .Y2J. • .Q, June 19TT: pp.15-g.--- -VlRABHADRA RAO, f., L. KlUSHNA KUMAR I AND S.Z. QASIH, 1976. Aquaculture of Green Mussel Mytilus viridis L.: Spawning, Fertilization and I,arval Development. Ind ian Journal of Marine Sciences Vol. 5, June, 1976; pp. 113-116. --..... 

Present status of mussel culture in India

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Present status of mussel culture in India

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