Commercial harvesting and economy of edible clam species in Bhatye estuary, Ratnagiri (MS), India

Indian Journal of Geo Marine Sciences Vol.42 (5), September 2013, pp 665-669 Commercial harvesting and economy of edible clam species in Bhatye estuary, Ratnagiri (MS), India V. M. Lagade 1, S. S. Taware & D.V. Muley Department of Zoology, Shivaji University, Kolhapur 416 004, India 1 [E-mail: vmlagade47@rediffmail.com ] Received;2 January 2012 revised 6 August 2012 Present study consists the annual harvesting and economics of commercially important edible clam species from Bhatye estuary, Ratnagiri (M.S.). Data collected by field and household survey and results were interpreted in two periods viz. July-Dec, 2008 and Jan-June, 2009. In Bhatye estuary, K. opima, M. meretrix, M. casta, P. laterisulca and P. textile are 05 edible clam species dominantly occurred while these species are commercially harvested on large scale by fishers of Bhatye village. Out of 350 families in village; 15.14% (53) families with 63 individuals engaged in clam fishing. Among this male individual s contribution was maximum than females. Annually 60.354 tones of catch were harvested by fishers. Maximum catch was harvested during Jan-June rather than Aug-Dec. In species wise catch, the Meretrix sps. were highly exploited than Paphia and Katelysia sp. respectively. Higher income was received from the above during Jan-June period. Meretrix clam received maximum income respect to other species. [Keywords: Edible clam species, Fishers, Harvesting and economy]. Introduction Estuaries are the connecting point where land meets the sea, where human influences on the terrestrial land-scape and on aquatic food webs interconnect. Both nutrient over-enrichment 1,2 and declining populations of species targeted by fishers 3,4 are common consequences of human influence on these coastal systems. Estuaries are particular targets for their historical importance as sources of nutrition and as places for disposal of human waste 5. Molluscs constitute a natural valuable resource of great extent in many parts of the world. Their range of distribution and abundance are varying with space and time and it covers the coastal habitats likes backwater, estuary, mangrove and sea grass beds. Molluscan resources include mainly, clam, oyster, mussel and chank. These resources have good food value due to its chief source of protein; as well as many industries like cement, calcium carbide, textile, paper etc. Manufacturer of lime based chemicals depends on lime shells, while some of the species showed medicinal importance 6,7. Removal of suspension feeders from temperate estuaries is thought to have reduced the capability of these systems to process nutrients 8. Harvesting suspension-feeder biomass has also been suggested as a tool to eliminate the consumed excess primary production and buffer coastal systems against nutrient enrichment effects 9. Molluscs species have been for long time a very important food source for human kind. Therefore, in bulk of commercial clam species are exploited throughout world and India as well. Among the exploited bivalve resources of India, clams are by far the most widely distributed and abundant. Several species belonging to a number of families constitute the clam resources and they are exploited all along the Indian coast 10. These resources provides livelihood to costal community, hence the fishers are massively participated in clam harvesting. Fishers showed less attention towards gastropod species due to its less food value. Molluscan resources of Bhatye estuary was earlier examined by researchers 11. Productivity and potentiality of molluscan resources at Bhatye estuary was astonishing and these resources on large scale were exploited by the fishers of Bhatye village throughout year for their local consumption and livelihood purpose. Data and literature on taxonomy, biology and eco-physiology of these mollusks is available, but less attention is given towards the molluscan fishery point of view. Therefore, the present work has been undertaken to study the harvesting and

666 INDIAN J. MAR. SCI., VOL 42, NO. 5, SEPTEMBER 2013 market value of commercially important edible clam species of Bhatye estuary. Materials and Methods The Bhatye estuary is located, on west coast, (16 51 N, 73 15 E) near Ratnagiri, Maharashtra. Bhatye estuary is one of the major and productive estuaries in Ratnagiri district and it formed by merging Kajali River to Arabain Sea, near Ratnagiri. Kajali river is perennial which originates from Sahyadri mountain ranges near Amba reserved forest. This estuary consists of an extensive swampy ground with scattered and diversified mangrove species. About 18 hectors of the area is situated near the mouth of Bhatye estuary. In present study, the survey was undertaken during July, 2008 to June, 2009. The survey was made on both way i.e. household and field observation. During low tide, the survey was performed at harvesting site, to study the distribution and abundance of edible clams and to collect the information on harvesting. Survey also made from households of Bhatye village, to collect the information on clam fishery. The information was collected by direct questionnaire and interview of fishers at site and from household on harvesting of edible clam species. Along with these surveys, the visits to local market at Rajiwada and Major fish market at Ratnagiri were carried out and contact with clam dealers, for collecting the economic assessment of harvested edible clam. During low tide, group of fishers, both men and women were engaged in harvesting the commercially important edible clam species at fishing ground. Fishers at Bhatye estuary harvest the clams by traditional hand picking method with digging by knife or besides this they used the clam fishing net. Mechanical or hand operated dredge were not used by fisher. The clam fishing net is semi-circular in shape with wooden or iron frame with nylon net having 30 mm mesh size, the local people called it as Yend. Both men and women operate this net to harvest the clam species during low tide but some of the women s were engaged in knife dinging and hand picking method. Fisher also used the small nonmechanized boat i.e. Dingi or dugout canoe during fishing for transport purpose. Female fishers likes to fishing in shallow water, while male fishers fishing at 3-4 feet deep water. During low tide, in shallow water the fishers are engaged 3-4 hours for clam harvesting. Fishers, simply turn over the sandy bottom with their feet to feel the presence of clams bed, after that they remove the sand by feet over the bed and drag out the buried clam in to net by feet and finally they collect in to nylon bag tied around waist or store in dugout canoe. The data collected during study period, on harvesting and economy of clam species was interpreted in two phase, July-December, 2008 and January-June, 2009. Clams were harvested by fishers was measured in kg, for data analysis it is converted in to tones and their incomes measured in rupees (Rs.). Results The edible clam species was widely distributed and found abundantly at Bhatye estuary. Total 05 clam species were dominantly observed from 03 genera of single Veneridea familiy. The species are Katelysia opima, Meretrix meretrix, Meretrix casta, Paphia laterisulca and Paphia textile. These 05 species have more commercial importantce due to its high edible value. Katelysia and Meretrix sp. were found in intertidal region during low tide from low water mark to mid water mark and their habitat was less sandy with more muddy flats. The bed of these species in Bhatye estuary was extended about 3½ km from Bhatye village to the interior part of estuary. Katelysia sp. and Meretrix sp. was found at depth of 8-10 cm. deep in soil. The Paphia sp. bed extended about 2 km. in interior part of estuary and it found at the depth of 10-12 cm. deep in soil. Paphia species was observed in deep water from shallow water to mid water mark and it also found in less sand and more mud habitat with empty and dead shell (Table 1). Both way survey was conducted, from household survey of Bhatye village and field observation, the total 350 household (HH) families were identified in village and out of this 15.14% (53) of families are clam fisher household families (CFHH). Among, those only 63 clam fishers (CF) were recorded, in which 57.14% (36) of male fisher and 42.85% (27) of female fishers were extensively engaged in clam fishing (Table 2). In total fishers, the maximum numbers of fishers from younger generation (age group 20-35 years) than old fishers (above 35 and below 50 ages) and child fishers (age group 10-20 years). The information on harvesting of clam species was collected from fishers during study period July, 2008 to June, 2009. Harvested clam species by fisher was

LAGADE et al.: CLAM SPECIES IN BHATYE ESTUARY 667 documented in two periods, July-Dec. and Jan-June. Fishers dominantly harvest 05 clam species from Veneridea family. Total 59 days during July-Dec and 67 days during Jan-June, the fishers were engaged for clam harvesting. Individual fishers showed distinct difference in species catch, i.e. Katelysia sp. about 5 kg and Meretrix sp. 10 kg while Paphia sp. is 7 kg were harvested per day (Table 3). The total clams harvested in Bhatye estuary was 60.354 tones, in which Meretrix sp. was maximum (32.760 tones) and is followed by Paphia and Katelysia sp. 14.994 and 12.600 tons respectively. Maximum harvested catch was observed in Jan-June period (32.093 tones) than July-Dec (28.261 tones) 12. The 1,100 tones catch of commercially important clam species were recorded from Thane to Ratnagiri region. In gender-wise catch of clam species, the male was dominantly engaged in exploiting the clam resource from Bhatye estuary rather than female. Total catch harvested by male fishers was 36.414 tones, out of them 17.051 and 19.363 tones clams were harvested during July-Dec, 2008 and Jan-June, 2009 periods respectively. Annually 23.940 tons of catch was harvested by female fisher. Female fisher harvested 11.210 and 12.730 tones of clams during July-Dec and Jan-June periods respectively. Maximum individuals of female fisher were engaged in Katelysia harvesting while males were busy in Meretrix and Paphia sp. (Table 4). Harvested clams by fishers were sold in the local and main markets of Ratnagiri while they sale catch directly to clam dealers. Fisher received 10, 15 and 20 rupees per kg for Katelysia, Meretrix and Paphia sp. respectively. In markets Paphia species have more demand due to its nutritive and delicious nature. Therefore the fisher got maximum benefits in less catch from this species. Total average income generated by clam fishing to the fisher was Rs. 9, 17,280, out of this; the fisher received more income during Jan-June (Rs. 4, 87,760) than July-Dec (Rs. 4, 29,520) respectively (Table 3). The gender-wise income of fishers showed that the male fisher was generating higher income (Rs. 5, 77,080) than female (Rs. 3,40,200). In both periods, the male fisher got maximum income (Rs. 2, 70,220 and Rs. 3, 06,860) than female (Rs. 1,59, 300 and Rs. 1,80,900) during July-Dec and Jan-June respectively. Maximum income was received by female fisher from Katelysia sp. Rs. 81,900 than male fishers (Rs. 44,100). While male fishers got maximum returns from Meretrix and Paphia sp. than female, (Rs 3,21,300 and 2,11,680 than 1,70,100 and 88,200) respectively (Table 5). By traditional way the fishers were extensive engaged in harvest of the edible clam resource from Bhatye estuary. The fisher used the semi-circular wooden or iron frame, clam fishing net of 30 mm. mesh size. Majority of female fisher was followed the digging by knife and hand picking method. Fisher also utilized the small non-mechanized boat or dugout canoe during fishing. Out of total 63 fishers, the 6.34% of fishers fishing with non-mechanized boat and 84.12% without non-mechanized boat while 9.52% of fishers followed knife digging and hand picking method. Maximum, 50.79% of male and minimum, 33.33% female fishers were fishing without non-mechanized boat and only 6.34% male fisher used the non-mechanized boat during fishing. 9.52% of female fishers were engaged in digging and hand picking method, the male fisher never followed this method (Table 6). Discussion There is limited demand for clams as food as they continue to remain as non-conventional item of food. There is need to develop acceptable products out of clam meat and a rigorous extension drive should be launched to expand the consumer market and explore the foreign markets. Such a step would result in increased production and also better market price 10. According to our observation in the field and earlier reference taken in to consideration, the edible clam resource was abundantly distributed in Bhatye estuary, and these resources were commercially exploited by local fisher for their livelihood and food purpose. Total 15 species of clams, from 08 genera, were observed at Bhatye estuary 11. But only 05 species of clams, of 03 genera, mainly from Veneridae family were exploited commercially by the local fisher. High edible value and ornamental usage, as well as the dry shells of clams are used in smallscale industries to manufacture the lime or cement. Therefore, the fishers of coastal community are commercially harvesting this resource throughout the year. Present work has been undertaken to acquaint with clam fishery, regarding harvesting and marketing of edible clam resource at Bhatye estuary. Detail account on fishery of Baby clam (Katelysia opima) from Ashtamudi backwater was studied 13. Survey was conducted in Bhatye village and at harvesting site and the information collected from

668 INDIAN J. MAR. SCI., VOL 42, NO. 5, SEPTEMBER 2013 Grampanchayat, Bhatye. Total 350 household families were living in village, out of them 15.14% (53) of the families were interested in fishing. 63 individual of clam fisher were identified, out of them 57.14% (36) are male and 42.85% (27) are female fisher. These fishers were extensively engaged in harvesting of edible clam resource of Bhatye estuary. Worldwide the clams have good food value therefore, it dominantly harvested from many parts of world in large magnitude. In Bhatye estuary, annually 60.354 tons of edible clam species were harvested. About 4,200 tones of oyster catch were exploited from Gulf of Kutch 14. Of all the maritime states, clam production of Karnataka State was intensively studied 15,16,17,18,19 & 20 the annual catch of clams are considerable fluctuates. In Bhatye estuary there was fluctuation in catch was observed during two periods of the year, the maximum catch of the harvested clam was reported during Jan-June period than the July-Dec. In species wise catch, the Meretrix species was abundantly harvested from site followed by Paphia and Katelysia species. In general, to identify which individuals actively participate in fishing in the estuary and received good returns from catch therefore, the gender wise estimation was made. In Bhatye estuary maximum catch of clams was harvested by male rather than female fisher. Maximum female individuals were involved in Katelysia sp. harvesting while the maximum males were engaged in Meretrix sp. The clams are marketed near the production centers either by numbers/volume. In Karnataka, P. malabaricus fetches the maximum price of shell-on weight, while M. casta, A. granosa and V. cyprinoides at Rs. 1.000, 500 and 200-400/t respectively 20. In this study, the market value for Paphia clam also high than Meretrix and Ketelysia sp. The total income generated from total harvested clam was Rs. 9, 17,280, out of that the maximum return from clam was found during Jan-June. Male fisher was received more benefit rather than female throughout the year. Female fishers only received maximum return from catch of Ketelysia sp. The live clams are collected by all age groups at low tides in shallow waters as well as in the intertidal zone. They are taken either by hand-picking or by using hand-operated scoop or rake nets 21. In Bhatye estuary, the maximum individuals were engaged in fishing without non-mechanized boat; only 6.34% of fishers used the small non-mechanized boat for transport of the clams. 9.52% of the female fisher followed digging and hand picking method. Those fishers fishing without boats, some of them used wooden planks or thermocol sheets for propulsions. The total edible clam resources exploited in Bhatye estuary received good returns in minor and major markets; the fisher also got many benefits in neighboring markets. Due to its good edibility and high market value 05 species of clams were irregularly harvested at estuary during every year. These resources fulfill the major requirements of coastal community like food, employment and livelihood. Therefore, the molluscan resource was exploited on large scale from different platforms like backwater, creek and estuary 22. The molluscan resource from Aghanshini estuary, west coast of Karnataka are exploited on large scale. To complete our needs, the humankind was irregularly exploiting this valuable resource and such uncontrolled activities could lead to deplete these resource. Thus, the present work was undertaken to collect accurate knowledge on harvesting of commercially important clam species in Bhatye estuary, and to estimate the actual harvested catch by local fisher and this information will helpful to predict the stock availability, potentiality and productivity of the estuary. Small sized clams were collected in considerable quantities both in the Ashtamudi and Vembanad Lakes 13,23. Such a practice would have adverse effect on the stock availability. In Bhatye estuary, net used for clams harvesting is less than 30 mm in size. Due to this, small clams were captured along with medium and larger clams, the fishers were used to store the small harvested clam in nylon net at shallow water. Conclusion In Bhatye estuary, there are no mechanical devices like dredgers is used for harvesting clam resources however, the fishers were capturing small size or nonmature clam and stores in shallow water due to this activity the clams resource/stock will affect. Fishers should utilize this resource at optimum level and sustainable fishery supposed to be required. Some governmental and non-governmental agency need to work in this sector and regularly monitor over these resource and harvester strictly. There must be develop the strict laws/rules in molluscan fishery, the local, state and central non-government or government agencies develop some ban period (during reproduction and development of clam). There is also

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