The support

and expanse of marketing network and advancement of

preservation technologies solved long standing problems

marketing in domestic as well as international market. In view

of its high demand in internal and international market, more

and more entrepreneurs are getting interested in the farming of

food fishes. Innovations in cage culture technology and its success

has drawn the attention of policy makers into giving thrust on

food fish culture. Those who have invested huge amount in

shrimp culture installations along the coastal areas are also

showing interest in switching over to food fish farming following

these developments and setback in shrimp culture

Dineshbabu, A P

CMFRI Digital Repository

Handbook on Open Sea Cage Culture137CAGE FARMING OFFINFISHES IN ESTUARIESA.P. DineshbabuThe importance and popularity of culture of food fishes isincreasing rapidly in coastal states of India. The supportand expanse of marketing network and advancement ofpreservation technologies solved long standing problemsmarketing in domestic as well as international market. In viewof its high demand in internal and international market, moreand more entrepreneurs are getting interested in the farming offood fishes. Innovations in cage culture technology and its successhas drawn the attention of policy makers into giving thrust onfood fish culture. Those who have invested huge amount inshrimp culture installations along the coastal areas are alsoshowing interest in switching over to food fish farming followingthese developments and setback in shrimp culture. In estuariescage culture is the most viable technique to rear fin fishes. Theindigenous technology is developed in cage culture of food fishesXV138Handbook on Open Sea Cage Culturein India. There are two general types of cages, floating andstationary. A floating cage is made up of a floating unit fromwhich a single or a series of netcages are suspended. Some ofthem are mobile and can be easily towed away. A stationary cage,on the other hand, is tied to fixed poles at their corners. In Asia,finfish like grouper (Epinephelus tauvina), seabass (Lates calcarifer),snapper (Lutjanus spp.) and siganid (Siganus spp.) are culturedin commercial scales in tropical countries such as Singapore,Thailand, Malaysia, Philippines, Indonesia and Hong Kong.Fishing and aquaculture are in the past have tended to betreated as distinct and isolated sectors. ‘capture-based aquaculture’is form of overlap between fisheries and aquaculture which isbeing propagated in many parts of the world successfully. Thefishing is put at the service of aquaculture or aquaculture ispracticed to avoid the loss of fishery due to juvenile exploitation.Capture-based aquaculture is the practice of collecting "seed"material – from early life stages to adults - from the wild, and itssubsequent on-growing in captivity to marketable size, usingaquaculture techniques.Capture Based Aquaculture (CBA) is a global activity buthas specific characteristics that depend on geographical locationand the species being cultured. The species groups used incapture-based aquaculture include molluscs (e.g. oysters, mussels,scallops), crustaceans (e.g. shrimps, crabs) and finfish (e.g. eels,grey mullets, milkfish, yellowtails, groupers, rabbitfish, tunas).In world wide CBA is practiced in many species following aresome of the species, with the countries where it is practiced.y Shrimp (Penaeidae) in South America and South-East Asia;y Milkfish (Chanos chanos) in the Philippines, Sri Lanka, PacificIslands and Indonesia;y Eels (Anguilla spp.) in Asia, Europe, Australia and NorthAmerica, mainly in China, Japan, Taiwan Province of China,The Netherlands, Denmark and Italy;Handbook on Open Sea Cage Culture139y Yellowtails (Seriola spp.), mainly in Japan, Taiwan Provinceof China, Viet Nam, Hong Kong, Italy, Spain, Australia andNew Zealand;y Tunas (Thunnus spp.) in Australia, Japan, Canada, Spain,Mexico, Croatia, Italy, Malta, Morocco and Turkeyy Groupers (Epinephelus spp.), which is now widespread inIndonesia, Malaysia,Philippines, Taiwan Province of China,Thailand, Hong Kong, People’s Republic of China, and VietNam, and in other parts of the tropics, for example insoutheasternUSA and Caribbean. Grouper culture is also on-going in India, Sri Lanka, Saudi Arabia, Republic of Koreaand Australia.These species are caught and farmed using various techniquesand systems, depending on different cultural, economic andethnical traditions. In some areas this is typically artisanal, ratherthan industrial in nature. Economic considerations are the keydrivers for capture-based aquaculture. The selection of speciesfor culture reflects their acceptability and demand in local orinternational markets. Market requirements are determinedprimarily by people’s tastes and customs. As capture-basedaquaculture potentially generates higher profits than otheraquaculture systems, the market demand for the products andspecies cultured is high and it is likely that efforts to promotethis activity will significantly increase. This development will becapable of causing a number of very important and diverse effects,not all of them beneficial.Cage based aquaculture is getting adopted rapidly in manyparts of the country. When it is being practiced in high intensitysome of the scientific factors has to be taken care.The number of cages should be according to the carryingcapacity of the water body and the number of cages exceeds itscarrying capacity, it will effect fish growth and survival.There is a strong need for better data on the biology and140Handbook on Open Sea Cage Culturefisheries of the species. Accumulation of uneaten feed and fishexcreta under the cage can become an environmental problem,but this can be avoided by selecting a site with good waterexchange to install the cage. Capture-based aquaculture providessignificant positive returns in areas with depressed and marginaleconomies, and an alternative livelihood for coastal communities.However, the difficulties of marketing fresh fish and supplyingmarkets that demand live fish (e.g. groupers), and the need toexpand markets limit its potential. Skill gaps are evident in thesector, including specific knowledge on economics andmanagement, the suitability of individual (new) species forculture, information on their biology and dietary requirements,and marketing. Capture-based aquaculture is labour intensivein its farming and processing operations, and can contribute topoverty alleviation in developing countries.Legal and security issuesWe will have to envisage some difficulties in future developmentof capture based aquaculture. Security of the cages is the majorissue. For leasing the inland waters and estuaries, the provisionswere made in the 73rd and 74th amendments to the Constitutionof India empower the panchayats to perform functionsmentioned in the eleventh schedule of the Constitution in 29subjects including fisheries. However, due to lack of legal claritythis has not been implemented in any panchayat. Leases policiesshould be guided by a set of rules and principles relevant topublic trust responsibilities and should specify the size of farm,duration of farming and other terms of lease. Rents thus collectedshould be used for development of coastal areas.Food safety issues The success of cage culture depends on maintaining good waterquality around the fish cages and so it is in the farmer’s best intereststo minimize environmental impacts. Size and intensity of theprocess should fit to the size of the water body and water exchangeHandbook on Open Sea Cage Culture141rate. It may facilitate to overcome adverse impacts on water andsediment quality. In common with other types of aquaculture,careful choice of aquafeed ingredients and on-growing sites, inaddition to good management practices, are necessary to avoidthe accumulation of chemical and antibiotic residues, in order toensure the continued safety of farmed products. Capture-basedaquaculture provides other opportunities to reduce the risksassociated with food safety.Demonstration experiments byCentral Marine Fisheries Research InstituteCentral Marine Fisheries Research Institute is one of the pioneerResearch Centres in transferring mariculture technologies in theState of Karnataka. The participatory approach gave exposure tothe local fishers on the finfish rearing aspects besides creatingawareness on this lucrative farming technique. Encouraged by thissuccess many fishermen group evinced interest in rearing finfishin suitable farming areas near their backyard.Karnataka state has 8,000 hectares of unpolluted brackish watersand estuarine areas, which are highly suitable for capture basedaquaculture. The local fishermen use dragnets, castnets and gillnetsin estuarine and coastal waters, which harvest juveniles ofcommercially important cultivable finfishes. These juveniles fishesthough live at harvest are invariably discarded due to low marketdemand. The juvenile of commercially important species such asredsnapper, pearlspot, mullets, seabass etc are available in theinshore waters of Karnataka for CBA.Seed survey for cultivable finfishesDetailed survey of the estuaries and coastal waters were donefrom Mangalore Research centre to study the availability of fishseed along the coast. The gears operated during the monsoonseason were hand trawls, cast nets and gillnets. It was observedthat during the monsoon season lots of juveniles of economicallyimportant species are also caught along with the market size142Handbook on Open Sea Cage Culturefishes. Etroplus and Gerres juveniles are caught in large quantityin Netravathi and Gangoli estuary. Usually these are discardedand efforts are made to collect these fishes and grow them in thecages as a part of CBA programme. Cages of netlon materialwas designed with inner nylon net to grow the juveniles discardedin fishery. Specially designed netlon cages fabricated locally withthe participation of the fishermen were used for farming. Thedimensions of the cages 2.5x2.5 m with a depth of 1.5 mProvisons were made to withstand water level changes duringhigh tide and low tide.Demonstration experiments in Karnataka The concept of CBA was introduced in this village bycollection of Lutjanus argentimaculatus, Etroplus suratensis and Latescalcarifer fingerlings and stocking in floating cages of 2.5 m x 2.5m x 2 m, made of Netlon (mesh of 30 mm) lined with nylon net.It was envisaged to use local seeds for culture, in addition to assuregood production seeds for Lates calcarifer was supplemented byCMFRI. The netlon cages was designed and fabricated by CMFRIwith the participation of local fishermen. Five cages were providedto the fishermen for stocking the fingerlings. The technology envisages the utilization of juveniles whichwere otherwise discarded due to small size, but if there is a highdemand for the seeds for cage culture, this exploitation may leadto stock reduction in estuaries and also lead to social conflictbetween capture fisheries and culture fisheries. The developmentof seed production in hatcheries on an economically viablecommercial scale, and the refinement of grow-out technologyto ensure that the fattening phase is environmentally acceptableare the critical issues for the future. Failure to address these matterssuccessfully would have severe consequences for both aquacultureand capture fisheries. So attempts are being made to complementthe CBA cages with hatchery reared finishes which may be a viableoption in the future.Handbook on Open Sea Cage Culture143Species Mean size Mean weight Numbers Harvestwt.(kg)Amount(Rs)Husbandry:The red snapper and pearlspot fingerlings were continuouslystocked by fishermen and the fishermen community was engagedin the cage setting, cage cleaning, feed sourcing, feed preparationand feeding. Feeding was done with locally available trash fishand also fish waste from fish processing areas/plants.Production and Harvest:Altogether five cages were installed and three of the cages werepartially harvested as and when the fishes were grown to marketablesize, to meet day to day needs of the fishermen. Two cages werespared for final harvest to demonstrate total production possiblefrom these cages.Theses cages were harvested during July, 2011, when themechanized fishing is banned. The Lutjanus sps attained an averageweight of 755 ± 415 g ranging from 105 to 1,914 g. The pearlspotranged from 37-222 g (96 ± 35g). About 255 numbers of seabassof average weight 1819 ± 540 g was harvested. The total productionfrom the cages including seabass, red snapper and pearlspot wasaround ~400 kg realizing a farm gate price of ~ Rs 75,000 per cage.Table 1.Harvest details (2 cages)350 ± 70 mm 755 ± 415gRed snapper (190-500 mm) (105-1914g) 105 150  27,000158 ± 17 mm 96 ± 35gPearlspot (115-205 mm) (37-222g) 988 150  22,500510 ± 50 mm 1819 ± 540gSeabass (310-620 mm) (262-3049g) 255 450  99,000 Total 1348 750  1,48,500Production per cage   375  74,250144Handbook on Open Sea Cage Culture The fishermen view this as an alternative source of fish whenadverse climatic conditions prevent them from venturing intothe sea. This concept could be popularized along the coast ofKarnataka and sustainable use of the finfish resources to augmentthe fish production could be done. Demonstration of thismethodology encouraged the fishermen to install cages of similartype in the estuary and at present many cages stocked withfingerlings of L. argentimaculatus, E. suratensis and L. calcariferare found in the village. Thus this concept of CBA was adoptedby the fishermen and the diffusion of the technology in thisvillage has been phenomenal. This concept could be popularizedalong the coastal Karnataka and sustainable use of the finfishresources to augment the fish production could be done. Thepopularization and adoption of the concept of CBA by thefishermen would generate alternate livelihood, income andcontribute to fish production of the region.

Cage farming of finfishes in estuaries

http://eprints.cmfri.org.in/9179/1/15_Dineshbabu.pdf

Cage farming of finfishes in estuaries

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