The most productive areas are the Kalbadevi estuary and

Bhatia creek in Ratnagiri District. Torkarli creek south of Malwan is also important. Clams are collected by men, women and children at low ntide by hand picking . Canoes and rake nets are also use

Narasimham, K A

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• i . • • REFERENCE 0 Nly SUI-IMER INSTITUTE IN \ CULTTIRE OF rnIBLE MOLLUSCS HELD AT TurrCCRIN RESEARCH CENTRE OF CENTP.AL l-I.ARINE FISHERIES RESEARCH INsrITUTE trom 26 May to 24 June 1980 ,. , . ~ Centr a l ~!arinc Fis her ies Research Institut e P .B . 1912, COGHill - 682018 , I NDIA " Indian Council of Agri cult1Z'al Resoarch September' , 1980 \.If \ .. 1 , FISHE1L AilD BI OLOGY OF CLAi£ AND COCKLES K • NA.1i!.SIMHAM a) 11eretrix meretrix (Linnaeus) Exploitation and fishery: Rai (1 932 ) estimated the prowction of this species and ¥.atelysia cmima :in t he erstwhile Bombay Presidmcy approxi-mat ely at 8818 tonnes . Ranade (1 964) stated that fran Thana to Ratnagiri District aboUt 3708 tonnes of the above t wo species are landed annually from 34 creeks . The r.ost productive areas are the Kalbadevi estuary and Bhatia cr eek :in Ratna.g:i.r i District . Torkarli creek south of Malwan is also important . Clams are collected by men, \~anen and children at low tide by hand picking . Canoes and rake nets are also used . Women market the clams at Bombay, Ratnagiri and Malwan and the last two places are impcrtant market centres for l:!.. mercrtrix (Alagarswami and Narasimham, 1973) • In Goa, Tiracol, Chapora, Sal, Mandovi and Zuari riVErS are imp<I'tant for clams in that <I'dar. This species is mainly fished at Siridao, Siolim and Ribandar . About 400 to 500 pErsons are engaged :in clam digging in Goa and fis h:ing is throughout year except the monsoon (Alagarswami and NarasimJ,lam, 1973 . Panaj i and Mapura are impcrtant 1llBl'ke-ting centr es • In the North Kanara District Kalinadi estuary has rich clam beds of !:1. meretrix. ImportlUlt clam fishing villages along tbe est)B"Y are Kodiba8h, Nandangadda, Sunkeri, Sadasivg~d Kanas giri. The above species is dominant on tho bank side of thJ estuary. Here 300 to 400 persons er e engaged in cl am fishing and 50 canoes are deployed for the plrpose. A chm net locally known as "Akbyn" is used. The annual output of clams from Kruinadi is about 1000 tonnes of which about 50% is by .1:1 . meretrix (Alagarswarni and Narasimhllm, 1973). othEr impOrtant centres for this species along the Ncrth Kan"z"" coast are Ankola , Moorba, Wadgoni creek, Mirj an, Horwada, Mudgian, Sanikatt a , Tadri and Aghanasini . Here clans are fis bed throughout the yoor with D. poak in Marc~June . Sanika-tta and Ankola ore important markcrting centres fer clams . In the exten-sive clam beds of the Sharawathi estu.:u-y l:!.. morstrix is the dominant species. On both sides of the estu,ry about 100 porsons r egularly collect the clams . • • , .; 63 -In. Tamil Nadu it is fished ori a small-scale in the estUll'ies of Adyar, Courtalayar, Vellar and Cooun (Nayar and !ohhadavan 1974). In the Kakinada Bay about 400 tonnes of this species are collected • annually (Narasimhami. 1973). It is also found in Pulicat lake ani Chilka lake. Present status of lIillity: The flesh of the clams is tasty bef<re they spawn and at this sta ge they are IDploited indiscriminately ___ _ (Nayar and Mahadevan, 1974) . Apart from their use as food the shells are used in lime making at several places like Kodibagh, Sadasiva-gsrh, S1lnkerl and Nand.md . Biology: Rai (1932) repcrted that the principal breeding season of !:!. meretrix on the Bombay coast lasts from March to June ani under favourable conditions it may continue yoor rOlIDd except. during monsoon. (h the east coast this clam spawns about the beginning of September and again in M9.y (Iarnell 1922 ) . M. meretrix can withs-tand low salinity of 10.5% 1IDder labarat<ry conditions when the change is effected suddenly. (h acclimatization to low salinity it can stand 5.0%. salinity (Ranade and Kulkarni 1973) and this helps the cl.a to survive' the l ow salinities prevhlent during the monsoon . b)- Meretrix casta (Chemnitz) , -Exploitation and fishery: -In South Kanara this species is imp<rtant in Coondapur, Silanadi, Malpe, Mulki, GtrpU' ani Netrllvati rivers (Alagsrswami and Narasim~ 1973). In t he Mulki river canoes are ~oyed to'ttranspart the women divers t o pick the clams whiCh are emptied into 'madi' (a piece of cloth folded like a oog) er- ;in a bag net fastened t o the:ir waists. The cllll!B are marketed at M9.lpe, Mnlgalar e and Mulki, Along the Kerala coast !:!. casta is ,?ne of the impOrtant. clams in most of the estmries and backwaters. At Kozhikode, Beypcre, VanbanM lake and Quilon this species is fished fer local consumption , / • • , .:. 64-In tlhe east coast !:!. ~ beds occur in the estmries of Athanlarai, Pinnakayol, Vaigai, VellaI', Msror, Gooun aIXl. bore back.:. watat's. The species is !mown to exist at Pulicat lake aIXl. Ch:ilka lake also. In the Adyar estmry, Eimore estuary !l.Irl Pulicat ~e each IOn!IIl collects ~4°O clams a day and on thickly pupulated beds 2()()(}.3000 clams may be picked up and taken home in baskets (Nayar . . . am fuhadevan, 1974). The clams are not; regularly sold in the markets and they are traded by bartat' s ystem flr commodities like paddy, sljests or pulses. utility: At 1Jllal r:en.r loWlgalore avar 3000 tonnes of lime is tr0duced wlued avat' Rs. 5, 00, 000 . ' The lime is us_ed in. manuring coffee plan-tations (Ala~s....:uni and Narasirnham, 1973). in (koowth: . In the Adyar estuary it gr O\~S t o a length of 4B.7 ~about 18 months. (koowth is retarded twic e i n a year (Atraham, 1953). It attains a size of 5613 nnn in about 3 years but nearly 90% of clams are fished before t rey r each 30 nnn length. An avera ge growth of 2.9 mm/ . .~ month was reported by Harkantra (1975) fran the KaJ.i estuary dU'ing the first year and 2.7 mm/month by Parulekar & ~ ( 1973) from Goa. ll1.mensional relationships in this species w<re studied by Dlrve and Illar=aja (1965) and Parulekar et ~ (1973). Dlrve (1975) obeerved . . change in the form of the shell dut'ing growth am suggested that it is essentially genot~ic. Condition facter: The pat'centage edibility (ratio of 'meat weight to the whole weight ) of !:!. casta of Eimore backwaters wried from 7 .t~ to 15.75 (Venkatarrumn and cmri, 1951 ), crrl at Goa it ranged from 11.26 to 12.08 (Kri shna K=i et al ., 1977). Bio-chemical compositiorl: The trotein varied fran 7.98 to 12.21%, fat 0.63 to 1 .1 % (Venkataranan and cmri, 1951). The:ir data show that the clams are rich in protein and minat'als. The caloric value of M. ~ Wl).S est ilmted a s 3369 cal/g dry wt. (Sunitra Vijayaraghavan et al., 1975 ) . Gopalal<rishntm ~ al., ( 1977) observed a high ¢otein content of 18.5% and gave the caloric ,¥hlue at 4755 cal/g. r , • \ ' '. • • ,;. 65 -Maturity: This specios is reported to attain seJOJal maturity at 11 nnn length and when one month old ~Y Alraham (195) ani at 10-25 DIn length by Harkantra (1 975) . Spawning: In the Adyar estmry M. casta spawns throui,holi; the year - - . with peak activity in Jul:,o-August, CCtober-Novanber ani March-April (Abraham, 1953) . Harnell (1922) stated that this species spawns twice in a year during April-May and in S~tember. Durve ( ,1964) recarded continuous spawnbg except far a. break in late SIlIIID9I' which related t o hypersaline conditions in the marine fish farm at Maniap1m. At Goa, continuous spawning throughout the year 'Nith a sligh!; peak in March-April wus observed by Krishm Kumari & &,,(1977) . Parulekar et al . , (1973) also stated that this species at Banastrim near Goa spawns throughout the year . Harkantra (1975 )r~crted tmt it breeds throughout the year in the Kali esttnry with a possible break in the winter. Parasites: Silas and Alagarswami (1967) ani Harkantra (1975) reccrded the pea-crab Pinnothet'es sp . in !:! . ~. They dallRge the gills, mantle, digestive glani and gonad . Durve (1964) observed that . .fl. .• few • !:!. ~ were parasitized by bucephalid cercaria . c) Villcrita cyprinoides (<ray) , The black clam is small and thick walled contributing to the clam fisheries along west coast. This species cannot withstand high ' salinities . ExplOitation ani fishery: In Goa it is fished at Siridao, Savoi, Amonen and Naibag . In t he Mangnlcr e ar ea also this species is fished and sold . Along t he Kerala ' backwaters it is availAble in the Cochin area and at several places to its south (Alagarswami ani Narasimham, 1973) . Utility: , Apart fr om its value as food the shells are used in the cement manufuctlr6 . ' The Travancore Cements Ltd ., Kottayam dredge annually: about 60,000 tonnes of' shells valued at Rs . 10, 80, 000 from the subfossil • • .,. \ - 66-deposits of tho VooDanad lake . About 10,000 tonnes of ..mite oement and 40,000 tonnes of I!}'BY cemmt are mnufactured &001 these shells (Alagarswami and Naras;imhwn, W 73). Nothing is known of the biology of the species . d) Kat elysia opima (<helin) This s pooios is of considerable impcrtance in Mnharashtra State. Exploitation and fishery: This s pcci es accounts for half of clam . . II' eduction in the Ratnagiri District. It is ext ensi vely fished at the Kalbadevi creek near Ratmg:i.ri :m:i Tarkarli creck near Malwan. It is next in lmportaroe t o ~. ~ on the east coast, especially at Adyer (Hayer and Mahadevun, 1974) . It is never foun:! in the interior of backwatocs where t he snlinity is low. utility: They are generally eat en by poorer classes people and the .-' shell is Ulled in t he preparation of lime • • Ck-owth: According t o .Rao (1951) t he life span is 3 years and clams of the si j!e 26-33 .8 mm in length are aver one year old . S~,."rly 38~8 to 43 .5 mm length are t wo year old clams. crCMt~ is arrested during August-December period when there is a fall in salinity~ In the Kalbadevi . estuary it attains a lEngth of 22 mm, 31 ~ and 43 UBll by t he end of 1,2 and 3M year respectively (t-bne, 1974a) . The growth r at e is not unifcrm throughout the year and it is rapid from Sept ember t o January, moderate &cm February to M3:y ani pv<r dUI'i.ng J"Ho-S"Irl;c:mber. The retarded I!}'CMth during too monsoon is ccrrelated with l ow salinity and. 1;t", Ill,*=bo.~o d ... ____ 0" ..t. this time were mru:le we in age determimtion (Mane, 1974a) . --.- ~. futurity: In the Adynr estuary first indica.tion of sem al matlrity • is observed in 11-12 UBll clnms when they are 3 months .old (Rao 1951). In Kalbadevi it attains sexual. matUl'ity at a size of 12 mm in males and 13 mm in females {Mane, 1974 a ) • " •• • 1. - 67-• Spawning: Spawning begins in Decanber in the Adyar estuary when the river is in communication with the sea and lasts about a month (Rao 1951) . In the Kalbadevi estuary the clams spa1lXlB twice a year; major spawning takes place in Mober-November and a mine: one confined to March-April period (Mane 1975). The spawning in MobEr is attributed to salinity and tempe':'ature rise. Physiology: Ranade and Kulkarni (1973) stated that 1£. opima tolerates a low salinity of 14.0% •• illlder laboratory conditions when the trans-fer to low salinity is sIDden . On acclimatization to low salinity its tolEl'ance limit comes down to 7.5%; Comparable results on salinity tolerance were obtained by Mane (1974b). Thwacclima;tisa,-tion has SllI'vival value d1lI'ing monsoon when the estuarine salini~ ties are 'low. e) Paphia 'spp . Papma malabarica. !:,. laterisulca. !:,. t-extile and !:,. marmorata are the COOlIllOll species exploited along the Maharashtra, Goa and North Kanara coasts. ~hia OCCllI'S along the Malabar coast and east.:coast. of India but not in abilllc1an'ce . Exploitation and fishEl'Y: E. laterisulca OCCtrS in "".ahim Bay and is found in most of the estuaries along the Maharashtra coast. In Ratnagiri District about 10% of the clam production is accounted by Paphia. In Goa it occ\%'s in Siolim, Siridao and Ribander. Near Karwar :in Kalinadi P. malabarica is abillldant (Alagarswami and - . Nsrasimham 1973). It OCC1lI'S in depths upt o L, metres :in sandy mID. IAlring low tide fishermen take smill scoop nets in one hand against the ctrTent and the clams Are pushed into the net with the ctha:- hani. They are fished thr oughout the year ~1ith a peak between January and July. IAlring peak fishing each individual collects 40 kg per day and about a tonne are landed daily in each centre (thyar and Mahadevan, 1974) • • • • - 68 -Biology of P. laterisulca: ·Mane (1979) studied its biology frOOI the Kalbadevi estuary. The clam grows to a length of 23, 38, 47 and 50 mm at the end of 1,2,3 and 3.5 years respectively. The rstardation of growth in the monsoon is attributed to low salinity and monsoon checks in the farm of annwl rings are formed. These were also used in age determination. SeXlBl maturity is attained at 16-18 mm, spawriing takes-place · from Septenber to March ,lith 2 peaks in November ·am March. r) ~ spp. ~ spp. are called wedge cl.= <r bean clams and are. widely distributed along the exposed sandy shares of our coast line. Exploitation and fishtry: Q. incarnatus Qnelin is camnon alcng . . , .~ -the Bombay coast, Goa, a m.nnber of Bays aromd KarWlI' and Cochin • . , Q. cunee.tus Linnaeus and Q. faba Qnelin are widely distrib1.t.ed . both along the east arxi west coasts. Q. scrlum Linnaeus is fairly , abundant along the Palk Bay and Gulf of Ma.nnar (Alagarswami and Narasirnham, 1973). Though they are o.bun:l.ant, at present thtre is no regular fishery for these clams as food or any organised lime making industry with the result the resource is neglected (Nayar and Mlhadevan, 1974). BialogY of D. cuneo.tus: ·At Palk Bay it grows to a size of 13 .. 14 mm in 11 months. The life span is two years and it grows upto 19 mm. Ring formation due to cessation of growth in Novanber-December was observed (Nayar ~ 1 955 ). At Ratnagiri it grows to a size of 13-14=, 21-22 and 22 to 23 rom within 1,2 and 2 . 5 years respectively. Q-owth was moderat e dU'ing Decmber-January, r apid dU'ing February-June and poor in JulJ"November. Fast growth in February-June is ccrrelated with rising salinity and the retarded growth during monsoon and winter with low salinity .(Tal il<hedkar et &., 1978) . The size at sexual maturity at Palk Bay is 10..13 llIIl when the clams ar e 10 months old. They spawn for the first time from January ... - 69 -• _. .-to April wen they are one year old and do not spmm more than twice during tpeir life time (Nayar, 1955). Spawning has been repcrt ed from Decembel' to June at Madras (Rao 1%7), and Octobel' to January • > at Ratnagiri ( Nagabhushanam and Talikhedkar 1977a). The pt'ot ein content varried fr om 56 .59 to 68 .)1 %,. glyQQgel). 11 . 1.~ to .25 .85% and fat in 56 tq 7;15 % (Ilagabhushanam and Talikhedk'ar , 1977b). Biology of D. faba : It gr ows to a length of 19.5 mm in t he first year and 23 .5 nun at t he end of second yea; at t'JaIlclapam . The life Spin does not seem to exceed 3 years . The clams reach semal maturity at 1~14 mm length . Spawning is prolonged, extending from Novembel' to June with two spawning peaks in Novanbel'- December and Ma~June . The average percentage edibility values ranged from 7.25 to-11.98 during differ~t months and ~. ~ app ears to be in the best condi-tion during August-Octobel' and Harch-t13.y period (Alagarswami, 19(6) . Biology of D. incarnlltus : At Goa. spat t hat settled in April grew r apidly and continuously for 8 months r eaching 21- 22 lIIIl lengcllby Decembtr. Growth was ·. slo'. for· the next 12 months and few alams swvived to. r each this age (Ansell et al ., 1972) . The same autliors ' obtained slightly slower growth for the same, species at Cochin. Ayyappan Nair ~ al (1978) reccrded a gr owth rllt e of 2.2/ mm/month for the same speci es at Goa and observed thllt growth was influenced by availability of particulat e organic carbon and chlorophyll !! in the surf water . Bio-ch E!llical st udies on this clam from Goa showed that fat varied from 7 .08 to 11 .56%, carbohydrate 4 .43 to 14. 12% and· protein 60 . 56 to 66 .94% en dry weight basi'S (Ansell at al 1<ri3Y.- . The average caloric value given by the sD.I!le authors is 1,650 cal/g dry weight. Anadara [,r&ll:lsa (Linnaeus) Members of the genus Anadara are popularlY called a s ark shells, blood clams and cockles. !. granosa is widely distributed along the east and west coasts of our country . It grows upto 70 nm. in • ... 70 -length . It forms a fishery second only to the windowpane oyster in the Kakinada Bay. Exploitation and fishery: a; granos a thrives well in soft muddy bottan with good amount of silt . In the Ka.1dnada Bay this clam is fished in the r egion from the intertidal upto 4 m depth waters . Fishermen fr om 15 villages around Kakinada fish for the clams throughott the year with a peak in March-~y • • ArulUal production is esti nnted at 1000 t onnes vn.lued at Rs . 50,000 (Narasimham, 1973) . o _ Present status of utility: They are eaten locally to a limited extent and occassionally used as medici ne . Shells are mostly bu-nt into l ime in kilns l ocally known as batties wit h the meat in tact . Biology: It gDowsfO a length of 31 . 5 IIUIl 49 .5 DIn at the end of 1st and 2nd year of life respectively . The COIlUlleI'CiD.1. catches chiefly consisted of clams below 2 years old . It attains seXU'lJ. nntuh ty at 21 mm length when 7 months old and appears to spawn throughout the year with peak act ivity in January-Ajril period (Naras:imham, 1969) . In additioto the clams dealt in the foregoing account there are a fow other species along our coasts which are fished to a lessa!' extent or practically unexploited but with a potential, mention may be made of the follmling . Meretrix cast"1 var 2Yl!!!! (Hanley) : It grows to a length of 35- 40 0 mm and is fishedLthe J.<:crala coast . LaJ.ong Tellina I2.inguis Hn:ll ny : It i s a brackish water form ani is among the important commercial cJams on the Bombay coast . Mesodcs= glabrnt um (lanm'ck) : It is common on the coarse sandy bmches of the islands of Gulf of ~ar ani is seldom fished . C'e.frarium tumidum Roding : Nearly 5 tonnes of this cockle clam are fished annuilly at Pamban and Rameswaram (Alagarswami and Narasimham, 1973) . • - 71 -~ ~ Preston: This has camnercial importance near Ratnagiri where aver 3 tonnes valued at Rs .2000/- are annually landed. It ·~o'oll to a length of 52.5 mm at the em of first year. Spawning takes place between late Cctobcr and March. Sexual ~mat1rity is attained when the clams are 5 months old . Diatoms and detritus fcrm the bulk of its food (Rao l!i sQ.., 1962) . Cardiun spp. The true cockles belonging to the genus Cardium are not abundant in our watar- s . We have a few species like £. asiaticum. Bruguiere and £. assimile Reeve distributed at several places but they do not constitute fishery. • 

Fishery and biology of clam and cockles

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Fishery and biology of clam and cockles

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