AQ-311 - Coastal Aquaculture and Mariculture -1.pdf

COASTAL AQUACULTURE AND MARICULTURE METHODS OF COASTAL AQUACULTURE AND UNIT 3 12 AQ-311...

COASTAL AQUACULTURE AND MARICULTURE METHODS OF COASTAL AQUACULTURE AND UNIT 3 12 AQ-311 (2+1) MARICULTURE Pg. UNITS CHAPTERS 3.1. Pond culture 12 no. 3.1.1. Site Selection 12 SHORE BASED AQUACULTURE AND 1 UNIT 1 3.1.2. Criteria to locate a good coastal farm site 13 MARICULTURE 3.1.3. Design and Construction of coastal ponds 13 3.1.4. Water Supply Systems 13 1.1. Sea farming and shore based aquaculture 1 3.2. Cages 14 1.1.1. Global aquaculture production – total 1 3.3. Pens 14 1.1.4. Global aquaculture production - by environment 1 3.4. Culture methods for oyster, mussels and seaweeds 15 1.1.5. Global aquaculture production - by species groups 1 1.2.1. Marine finfish 2 1.2.2. Crustaceans – shrimps 3 UNIT 4 WATER AND SOIL QUALITY MANAGEMENT 16 1.2.3. Crustaceans - spiny lobsters 3 1.2.4.Molluscs 3 4.1. Water and soil quality management 16 1.2.4.1. Molluscs - major producers 4 4.1.1. Physical variables 16 1.2.5. Sea cucumbers 4 4.1.1.a. Temperature 16 1.2.6. Sponges 5 4.1.1.b. Salinity 16 1.2.7. Corals 5 4.1.1.c. Turbidity 16 1.2.8. Seaweeds 5 4.1.2. Chemical variables 17 1.3. Resources for Shore-based aquaculture and seafarming in india 5 4.1.2.a. Dissolved oxygen 17 1.3.1. Status of Coastal Aquaculture 6 4.1.2.b. Total alkalinity 17 1.3.2. Aquaculture Diversification Programmes 6 4.1.2.c. pH 17 1.3.4. Diversification of Coastal Aquaculture – MPEDA’s initiatives 7 4.1.2.d. Carbon dioxide 17 1.3.5. Conclusion 7 4.1.2.e. Ammonia 17 1.4. Seed resources of finfish and shellfish 8 4.1.2.f. Nitrite and Nitrate 17 1.4.1. Finfish Seed Resources 8 4.1.2.g. Hydrogen sulphide 18 1.4.2. Shellfish seed resources 8 UNIT 5 FINFISH CULTURE SYSTEMS 18 UNIT 2 TRAITS OF IMPORTANT CULTIVABLE SPECIES 9 5.1. Culture of milkfish 18 2.1. Grey Mullets 9 5.1.1. Culture systems 18 2.2. Milkfish 9 5.1.2. Fry collection 18 2.3. Pearlspot 9 5.1.3. Artificial propagation 19 2.4. Asian seabass 10 5.1.4. Grow-out 19 2.5. Groupers 10 5.1.5. Pond preparation 19 2.6. Snappers 10 5.1.6. Water management 20 2.7. Shrimps 10 5.1.7. Supplementary feeding 20 2.8. Lobsters 11 5.2. Culture of grey mullets 20 2.9. Crabs 12 5.2.1. Culture systems 20 5.2.2. Fry collection 20  5.2.3. Grow-out operations 21 5.3. Culture of asian seabass 21 5.3.1. Source of seed 22 5.3.2. Grow-out culture 22 5.4. Culture of groupers 22 5.4.1. Biology and Seed supply 22 UNIT 6 CULTURE OF CRUSTACEANS 23 6.1. Shrimp Culture 23 6.1.2. Culture systems 24 6.1.3. Characteristics of shrimp culture systems 25 6.1.4. Considerations for the choice of technology 25 6.1.5. Grow-out operations 26 6.1.5.a. Pond preparation 26 6.1.5.b. Selection of shrimp fry (post larvae) 26 6.1.5.c. Stocking 26 6.1.5.d. Feeding 26 6.1.6. Water quality management 27 6.1.7. Aeration and Harvesting 27 6.2. Mud Crab Culture 27 6.2.1. Culture methods 27 UNIT 7 CULTURE OF MOLLUSCS AND SEAWEEDS 28 7.1. Oyster Culture 28 7.1.1. Culture techniques 28 7.1.2. Oyster culture in India 29 7.2. Mussel Farming 29 7.2.1. Grow-out 29 7.2.2. Seed collection 29 7.2.3. Growth and production 30 7.3. Culture of Pearl Oysters 30 7.3.1. Biology 30 7.3.2. Culture methods 30 7.3.3. Culture of Seaweeds 31 7.3.4. Main groups of algae cultivated for food 31 7.3.5. Culture systems 31 COASTAL AQUACULTURE AND MARICULTURE (2+1) .Seawater ( in the sea and also in the ponds) accounted for 32.3 percent by quantity and 30.7 percent by value (both plants and animals). Majority of this production comes from the farming of seaweeds. While, low volumes UNIT 1 - SHORE BASED AQUACULTURE AND MARICULTURE of high value finfish, crustaceans and abalones are grown in seawater; low 1.1. Sea farming and shore based aquaculture value oysters, mussels, clams and cockles are grown in large quantity. "Aquaculture" is the farming of aquatic organisms, including fish, molluscs,  Brackish water aquaculture produced 7.7 percent of the total aquaculture crustaceans and aquatic plants. Farming implies some form of intervention in the production by quantity but a high value of 13.3 percent reflecting the rearing process to enhance production, such as regular stocking, feeding, dominance of more valued crustaceans and fin fish produced in this protection from predators, health management, genetic improvement etc. Farming environment. also implies individual or corporate ownership of the stock being cultivated (FAO definition of aquaculture). "Coastal aquaculture" is the farming of aquatic organisms in land-based facilities such as , ponds, tanks, pens etc. in the coasts using brackish or salt water. It is also known as ‘shore based aquaculture’. “Mariculture” or " sea-farming" is the term used for farming of aquatic organisms in the open sea, away from the shore, mainly in cages (fish and crustaceans) or using rafts or long-lines (for molluscs and seaweeds). 1.1.1. Global aquaculture production - total  Aquaculture is a relatively recent, fastest growing food production system.  It has grown at an annual rate of 8.3 percent between 1970 and 2008, while the world population grew at a rate of 1.6 percent during the same year.  This has resulted in annual per capita supply of food fish from a mere 0.7 kg in 1970 to 7.8 kg in 2008 through aquaculture.  The global production food fish through aquaculture stood at 52.5 million tonnes valued at 98.5 billion US dollars in 2008, accounting for 45.7 percent of the total world fish production by quantity and 51.2 % by value. 1.1.5. Global aquaculture production - by species groups  The total aquaculture production including both plants and animals was 68.3  Carps grown in freshwater dominated aquaculture production in 2008, million tonnes, valued at 106 billion US dollars. while mariculture and coastal aquaculture production comes from oysters, clams, shrimps, mussels, scallops, pecten , miscellaneous mollusks and  The output from world aquaculture has increased substantially in the last 6 salmons. decades, up form a meager 1 million tonns in 1950 to 52.5 million tonnes in 2008 and is predicted to grow further, although the rate of increase may slow  Carps contributed 20.4 million tonnes or 71.1 percent of the food fish down. production from aquaculture in 2008.  Since the fish production from capture fisheries has stagnated around 90  Oysters formed the main component of production of mollucs contributing million tonnes since the mid 1980s, aquaculture is expected to supply the ever to 31.8 percent. Other molluscs produced are clams (26.4%) mussels (12.4 increasing demand for fish. %), and scallops (10.7%). 1.1.4. Global aquaculture production - by environment  The production of high value abalones (molluscs) for luxury market grew from 2 800 tonnes in 2000 to 40 800 tonnes in 2008.  Freshwater production contributed to 59.9 percent by quantity and 56.0 % by value in 2008 1   2.4 million tonnes of crustaceans were produced in brackish waters while, Traditionally, much of their production has been of milkfish, but production is 1.9 million tonnes were produced in freshwater and 0.7 million tonnes in diversifying to include more difficult to rear species such as groupers. marine waters. At the other end of the spectrum are the large technology-dependent hatchery  Production of Atlantic salmon (1.5 million tonnes) dominated the systems that have been developed in Australia and Japan. Much of the hatchery production of diadromous fish, while 0.68 million tonnes of milkfish 0.58 technology in use in Australia has been adopted from Europe and modified to meet million tonnes of rainbow trout and 0.26 million tonnes of eels were local conditions. A major focus in developing hatchery technology in Australia in produced. particular is the need to reduce labour inputs because of high labour costs. Taiwan PC has established itself as a major seed stock production centre for the Asia-Pacific region, with around 1 000 farms involved in producing fry and juvenile marine finfish. Marine finfish production in Taiwan PC is typified by highly specialized production sectors: e.g. one farm may produce eggs from captive brood stock, a second will rear the eggs, a third may rear the juveniles through a nursery phase (to 3–6 cm TL) and a fourth will grow the fish to market size. Nursery There is substantial mortality of juvenile seed stock captured from the wild. Cannibalism among hatchery-reared juveniles is a major cause of losses in many species. Transportation of fingerlings also results in losses. Grow-out technology Grow-out technology employed in the Asia-Pacific region ranges from small floating or fixed cages used by small family-run operations, to extremely large cages (15x15x15 m) used for amberjack grow-out in Japan or 30–50 m diameter 1.2.1. Marine finfish circular cages used for southern bluefin tuna grow-out in Australia. Much of the marine finfish aquaculture production in the Asia-Pacific region Seedstock production is from small to medium-scale farms. Many farms use relatively simple Hatcheries are producing greater numbers and a wider range of marine finfish technologies, with wooden or bamboo cages and plastic barrels or polystyrene species, but the industry is still heavily reliant on capture of fingerlings for grow- blocks to provide buoyancy. However, Japan and Australia in particular use larger out, particularly for species that are difficult or costly to raise in hatcheries, such as and more sophisticated cage systems. In the case of Australia, these are based on grouper or Napoleon wrasse or for which there is no established hatchery European technologies. The traditional Asian cage system is suited to sheltered technology, such as tunas. inshore waters. In general, the availability of seed from wild sources is in decline through over- As coastal sites have become increasingly crowded, several countries have fishing and habitat destruction. Consequently, there is a need to develop begun to adopt cage designs that can withstand more open water. These offshore sustainable technologies for seed production, particularly hatchery production. cages have been based on Japanese and European designs. The ability to site farms in more open water has opened up more coastal area for farming. Hatcheries range in size and technology. In Asia there has been considerable A major issue regarding the continued proliferation of marine finfish development of small-scale or backyard hatcheries that have only a couple of aquaculture in the Asia-Pacific region is the environmental impact of such larval rearing tanks. These hatcheries use basic but effective techniques to produce operations. Although there is now a good understanding of the environmental large numbers of seed stock of a range of marine finfish species. impacts of cage aquaculture in temperate environments, there has been relatively little work done in tropical systems. 2 1.2.2. Crustaceans - shrimps In the Philippines, the preferred size at stocking is 100–300 g, and it takes 6–15 By far the greatest tonnage of farmed crustaceans are brackish water and months for the lobsters to grow to the optimum size of 0.8–1.3 kg. Survival is marine shrimps in the Asia-Pacific region. Effectively all of this production is around 90 percent, although stocking smaller lobsters (30–80 g) reduces survival undertaken in coastal ponds under extensive, semi-intensive an intensive systems. to less than 50 percent. Such is the scale of shrimp farming, that it induced significant changes in market 1.2.4.Molluscs structure and prices since the 1980s. Bivalves are a major component of aquaculture production in the Asia-Pacific An abundance of shrimps in the region. Much of this production is based on the culture of mussel, which is a high- medium size ranges (20-32g) caused volume, low-value commodity. In the Asia-Pacific region, Thailand and the a fall in prizes in south east Asia. The Philippines are the largest producers of farmed mussels primarily the green mussel decline in prizes emphasized the (Perna viridis). At the other end of the spectrum, there has been substantial vulnerability of intensive farming production of pearls through farming, which produces an extremely low-volume methods which have narrower profit but high-value product. margins than many low cost extensive farms. Production in some Despite the fact that hatchery production technologies have been developed for countries has been adversely affected many bivalves, most tropical bivalve culture still relies on collection of seed stock by a number of factors in recent from the wild. Artificial settlement substrates such as bamboo poles, wooden years, notably the outbreak of stakes, coconut husks or lengths of frayed rope are used to collect bivalve spat at diseases and fluctuation in prizes. settlement. The spat may be transferred to other grow-out substrates (“relayed”), or cultured on the settlement substrate. Seed stock is produced mainly in Molluscs - culture methods hatcheries though brood stock comes mainly from the wild in Asia. There There are two major systems commonly used for bivalve culture is a widespread shortage of wild  On or just above the bottom – brood stock (more on the status of shrimp aquaculture is presented in the chapter: Shrimp Farming). This culture system is commonly used for culture of bivalves that tolerate intertidal exposure, such as oysters and mussels. Rows of wooden or bamboo 1.2.3. Crustaceans - spiny lobsters stakes are arranged horizontally or vertically. Bivalves may also be cultured on Tropical spiny rock lobsters (Family Panuliridae), and particularly the racks above the bottom in mesh boxes, mesh baskets, trays and horizontal ornate lobster (Panulirus ornatus), are cultured in Southeast Asia, with the bulk of wooden and asbestos-cement battens. production in Vietnam and the Philippines.  Surface or suspended culture – Lobster aquaculture in Vietnam produces about 1,500 tonnes valued at around US$40 million per annum. Tropical spiny rock lobsters are cultured in cages. In Bivalves are often cultured on ropes or in containers, suspended from Vietnam, fixed, floating and submerged net cages are used, the former in shallow floating rafts or buoyant long-lines. Management involves thinning the sheltered areas where the cages can be fixed to the substrate. Submerged cages are bivalves where culture density is too high to support optimal growth and mainly used for nursing juvenile lobsters and are located in shallow water. A development, checking for and controlling predators, and controlling feeding pipe allows feed to be dropped into the cage, and limits the depth at which biofouling. this system can be used. Floating cages may be used in depths up to 20 m. Seed Tropical mussels grow to market size (about 5–7 cm shell length) in less stock is obtained from the wild. In Vietnam, coconut logs are drilled with holes to than one year, and in many cases 6–7 months, after settlement. Production can provide an artificial substrate for puerulus/juvenile settlement. Once settled, the reach 1 800 tonnes per ha annually but may be lower in some areas. With a juveniles are removed from the logs and placed in nursery cages. Lobsters are fed cooked meat yield of around 20 percent, this is equivalent to 360 tonnes of exclusively on fresh fish and shellfish, using about 70 percent fish and 30 percent cooked meat per ha per year). shellfish. In Asia, farmed mussels are generally sold as whole fresh product. Some products are simply processed, e.g. shucked and sold as fresh or frozen meat. 3  There has been some development of longer-life products, including canned Bioeconomic evaluations of mussel culture in the Philippines indicated a low and pickled mussels. return on investment for mussel farming, although farming in Thailand and Malaysia compared favourably with other forms of aquaculture. 1.2.5. Sea cucumbers  The most commonly cultured sea cucumbers are the temperate Japanese sea cucumber (Apostichopus japonicus) and the tropical sandfish (Holothuria scabra).  Aquaculture production of H. scabra is low and is generally still in the experimental phase.  However, there is substantial production of A. japonicus from both land- 1.2.4.1. Molluscs - major producers based aquaculture and mariculture in China and Japan. Estimated Chinese China and Japan are the largest producers of cultured scallops, with the bulk of production of A. japonicus in 2003 is 6 335 tonnes, of which 5 865 tonnes production being the yesso scallop (Pecten yessoensis). Production in 2003 (93 percent) were from cultured production and only 470 tonnes from the exceeded 1.1 million tonnes of yesso scallop. Preferred harvest size (>10 cm shell wild fishery. length) is reached in 2–3 years. Giant clams (Family Tridacnidae) have been  Farming of A. japonicus is well established in northern China. Most cultured in many Pacific Island countries. Their relatively slow growth rates make production is from earthen ponds, but there is also some mariculture using tridacnid clams suitable only for extensive aquaculture or stock enhancement. sea cages on the substrate or suspended below rafts. Much of the tridacnid aquaculture production is sold to the marine ornamental market, which provides higher and more rapid returns.  The sea cucumbers are fed Sargassum and other macro-algae. In contrast, sea cucumber farming in southern China is only beginning and is likely to Pearl oysters are farmed in Japan, China, Australia, Indonesia and in several utilize the species Holothuria scabra, H. nobilis and H. fuscogilva. Pacific Island nations, notably French Polynesia and the Cook Islands. Pearl culture is technically intensive, particularly the process of inserting a nucleus to  In Japan juveniles of A. japonicus are stocked in coastal waters to promote formation of a pearl. The period between nucleus insertion and harvest replenish local stocks or to develop new harvest fisheries. generally ranges between nine months and three years. The quality of the pearl is  In Indonesia, H. scabra is farmed in cages of 20x20 m or 40x20 m in related to the length of the culture period, but many insertions are unsuccessful, shallow (0.75–1.0 m deep) coastal areas or in coastal fish ponds. Organic resulting in the death of the pearl oyster or ejection of the nucleus. Pearl oysters material (such as rice bran and animal dust) is added at 0.2–0.5 kg per m2 are usually grown out using suspended culture systems in which oysters are every two weeks. Holothuria scabra grow relatively slowly and it takes usually suspended below rafts or on long-lines. approximately six months to reach the preferred harvest weight of 200– Due to their filter-feeding nature and the environments in which they are 250 g. Seed stock supply is mostly from the wild, although there is some grown,edible bivalves are subject to a range of human health concerns, including hatchery production of juveniles. accumulation of heavy metals, retention of human health bacterial and viral Seed production technology pathogens, and accumulation of toxins responsible for a range of shellfish poisoning syndromes. One option to improve the product quality of bivalves is Seed production technology for several sea cucumber species is well established in depuration, which is commonly practiced with temperate mussels, but rarely used China. Since the 1980s approximately 6–8 billion juvenile A. japonicus have been in the tropics. produced. In 1994, 2.6 million seeds were produced in Japan. Techniques for production of H. scabra have been developed in India, Indonesia, the Solomon A major constraint to the development of tropical mussel culture is limited Islands, New Caledonia, Vietnam and Australia. Constraints to hatchery demand and low price. Although prices are higher in Australia and New Zealand, production of H. scabra in Indonesia include accessing suitable brood stock and mussels are still relatively low-priced compared with other seafood commodities. low rates of survival to juvenile. Sea cucumbers require large areas for nursery The low economic value of mussels is compensated for by their ease of culture and and grow-out phases because growth rapidly becomes limited as density increases. high productivity. For this reason, there has been considerable focus on their use for sea ranching. 4 1.2.6. Sponges  Seaweeds are grown for  Sponge aquaculture is generating considerable interest in the research Direct consumption, either as food or for medicinal purposes; production of community, but commercial production of farmed sponges in the Asia-Pacific the commercially valuable polysaccharides alginate and carrageenan; used as region is low. fertilizers; and feed for other aquaculture commodities, such as abalone and sea urchins.  There is a small commercial farm in Pohnpei (Federated States of Micronesia) and several experimental operations in Australia, New Zealand and the Production technology Solomon Islands. Because cultured seaweeds reproduce vegetatively, seed stock is obtained from cuttings. Grow-out is undertaken using natural substrates, long-lines,  Sponge aquaculture is similar to seaweed culture in that sponges can be rafts, nets, ponds or tanks. propagated vegetatively, and little infrastructure is necessary to establish farms. Production technology for seaweeds is inexpensive and requires only simple equipment. For this reason, seaweed culture is often undertaken in  The harvested product (for bath sponges) can be dried and stored and does not relatively undeveloped areas where infrastructure may limit the development require infrastructure such as refrigeration. Consequently, like seaweed of other aquaculture commodities, for example in Pacific Island atolls. culture, sponge culture may be ideal for remote communities, particularly in Existing technologies rely on tying individual plants to lines and are time- the Pacific. consuming and limit production.  However, the market acceptance and economic viability of commercial sponge Selective breeding for specific traits has been undertaken in China to farming has not yet been established. Further assessment of basic biological improve productivity, increase iodine content and increase thermal tolerance to parameters such as growth and survival, as well as development of marketing better meet market demands. More recently, modern genetic manipulation channels, is necessary before large-scale sponge aquaculture can be developed. techniques have been used to improve temperature tolerance, increase agar or 1.2.7. Corals carrageenan content and increase growth rates. Improved growth and environmental tolerance of cultured strains are generally regarded as priorities  There has been some small-scale development of coral farming in the Pacific for improving production and value of cultured seaweeds in the future. Islands. Both soft and hard corals have been cultured, primarily for the marine aquarium trade, although some hard corals are sold as curios or used for Seaweed aquaculture is well suited for small-scale, household-level restoration of degraded areas on coral reefs. business operations run by people living in rural coastal communities. Seaweed fisheries are traditionally the domain of women in many Pacific  Corals are propagated vegetatively. Small pieces of live coral are glued to Island countries, so it is a natural progression for women to be involved in bases, and these are placed on underwater “tables” fitted with galvanized wire seaweed farming mesh. Growth is reportedly rapid, with aquarium corals reaching harvestable size in 3–12 months. Because of the low level of capital investment needed 1.3. Resources for Shore-based aquaculture and seafarming in india and the relatively simple propagation methods used, coral culture is suitable  Sea farming has become a promising area of aquaculture all over the world for remote coastal communities where infrastructure may be lacking. and is one of the most important and rapidly growing components of Asian 1.2.8. Seaweeds aquaculture contributing substantially to the increased demand for high value Aquatic plants are a major production component of mariculture in the Asia- seafood items in the global market. Pacific region. About 13.5 million tonnes of aquatic plants were produced in 2003.  India has a long tradition of aquaculture from time immemorial and is a leader China is the largest producer, producing just less than 10 million tonnes. The in the world after China, contributing to about 5.2% of the total production in dominant cultured species is Japanese kelp (Laminaria japonica). 2003.  There are around 200 species of seaweed used worldwide, of which around ten  A sub continent, with seas all around on three sides, India has a long coastline species are intensively cultivated, including the brown algae L. japonica and of about 8129 km. The country’s continental shelf is estimated as 0.5 million Undaria pinnatifida, the red algae Porphyra, Eucheuma, Kappaphycus and square km, within its Exclusive Economic Zone (EEZ) that extends to 2.2 Gracilaria, and the green algae Monostrema and Enteromorpha. million square km. 5  The southern edge of the Indian peninsula extends in to the Indian Ocean, with  The shrimp farms in the country have been periodically affected by white spot the Bay of Bengal in its eastern part and the Arabian Sea in the west. The main syndrome viral disease and the farmers are adopting various management land is surrounded by groups of islands both in the east as well as the west measures to prevent crop loss and ensure sustainable production levels. coasts.  The Marine Products Export Development Authority (MPEDA) of  The Andaman and Nicobar group of Islands are located in the Bay of Bengal, Government of India has been playing a major and significant role for while the Lakshadweep group of islands are scattered in the Arabian Sea. promoting coastal shrimp and scampi cultivation in the country, as shrimps  The sea coast along the main land and around the islands provide vast scope constitute the major revenue earner in the export market. for development of sea farming, which has considerable potential to augment  The revolution in coastal shrimp culture started when MPEDA established two production of seafood for the domestic as well as export markets. modern shrimp hatcheries in the east coast, with overseas technological tie-up. 1.3.1. Status of Coastal Aquaculture Subsequently, scientific commercial shrimp farming practices were also demonstrated to farmers through pilot projects. This sector, which has  India has a coast line of 6517 Km (mainland), a continental shelf of about 40 witnessed a sudden upsurge with large-scale development, faced several million hectares and brackish water area of about 1.7 million hectares. challenges from environmentalists, lawmakers, financiers, etc. apart from in-  The east and west coast of India are productive and are suitable for house problems such as the onslaught of diseases. undertaking mariculture, while the edges of the seas offer scope for large scale  However, the situation got stabilized and now streamlined with the enactment culture of organisms such as oysters, mussels and seaweeds. of the Coastal Aquaculture Authority Act facilitating statutory and regulatory  The open seas could be used for suspending rafts and cages for the culture of control over coastal farms. Small and marginal farmers largely run the shrimp finfish and shellfish. culture sector in India. In order to empower these farmers, MPEDA has mooted the concept of forming “Aquaculture Societies” in various farming  Despite the huge potentials, the development of coastal aquaculture in India villages, through a project undertaken by MPEDA in association with the has been rather confined to brackish water shrimp culture in the maritime Network of Aquaculture Centers in Asia-Pacific (NACA), Bangkok on Shrimp states. Disease Control and Coastal Management in India.  In fact, the country has a rich tradition in shrimp culture, as various traditional  Aquaculture societies are expected to improve the socio-economic condition practices were followed in different regions to grow and harvest shrimps in its of the small scale and marginal farmers by assuring them sustainable natural habitats. production levels through adoption of Better Management Practices (BMPs) to  Taking a cue from the traditional practices, scientific systems have reduce the risk of diseases and improve production and productivity. subsequently been evolved to culture shrimps in protected and manually  The country is estimated to have about 1.2 million ha.of areas, suitable for controlled regimes. Presently, over 1,67,500 ha area is under shrimp farming undertaking brackish water aquaculture. However, the development so far, has in various coastal states, out of which as much as 50,000 ha is still adopting been only about 15% of the available area, and the scope for further expansion traditional practices. is therefore enormous.  Presently there are about 350 hatcheries in India with a built in capacity of 14  In order to regulate the development of coastal aquaculture in an billion seed per annum to supply quality seeds of both shrimp and scampi. environmentally and sustainable manner, the Coastal Aquaculture Authority Broodstock collectors, nauplii producers, nurseries, water quality analysis (CAA) has been authorized by the Government of India to license the aqua laboratories, PCR Labs etc are also functioning to support the operations. farming activity in the coastal region for which, the norms and guidelines are  Another vital sector for the sustainable development of coastal aquaculture is already framed by the CAA. This Authority, although national in character the feed and feed inputs. Over 30 domestic feed mills are supplying shrimp will be working through the state governments for the governance of coastal feed to the farmers, apart from the imported brands. Various forms of other aquaculture sector. inputs such as probiotics, immunostimulants, Zeolite, BKC etc are also 1.3.2. Aquaculture Diversification Programmes marketed to help successful crops.  As stated above, the development and progress of coastal aquaculture efforts in India have been concentrating mainly on shrimp or scampi so far 6  especially in the coastal areas on the landward side due to their economic diversification of coastal aquaculture, MPEDA has, constituted a separate Society importance, as well as the ready availability of technology and ready viz, Rajiv Gandhi Centre for Aquaculture (RGCA). RGCA has embarked upon market for the produce. Pilot or experimental trials have been attempted various missions to standardize and popularize the aquaculture of potential species for other species of commercial importance. The Indian research institutes in Indian waters, which have commercial significance. have already standardized the breeding technologies for many of the The following are some of the activities recently taken up by this organization. potential species in our waters. However, commercialisations of such a) Breeding of Asian Seabass (Lates calcarifer) efforts have not been materialized due to various reasons. The potential candidates for mariculture in Indian coast are listed in the following b) Cage culture of Asian Seabass animation. c) Fattening of Rock Lobsters  Pioneering experimental level works on breeding and rearing of various d) Breeding and culture of Mud Crabs (Scylla serrata) potential species have been carried out in India by the ICAR research e) Artemia production institutes like Central Marine Fisheries Research Institute (CMFRI) and f) Breeding and culture of Groupers others, as early as 1970s. g) Tilapia culture  These pilot scale attempts have proved that the breeding and rearing of the potential species are possible and the technology was made available for The MPEDA has also taken up few demonstration projects in the farmers’ transferring to the entrepreneurs. pond for encouraging the farmers to take up alternate culture of species such as  However, the transfer of the technology did not result in large-scale Sea bass, Mullets, Milkfish, Mud crabs, Mussels, Oysters and Clams. development of mariculture activities due to lack of policy to attract With a view to propagate mariculture in the country, a detailed feasibility investment in this sector. Hence, the coastal aquaculture remained as an study was undertaken during the 1990’s; through an overseas agency to micro infant and focused only towards shrimp culture, for nearly three decades. survey the Indian coast for studying its potential for offshore farming. The survey  However, there have been attempts by private entrepreneurs to start pond revealed that India has great potential for offshore farming, along the continental culture of finfishes such as Seabass, Milkfish, etc. Fattening projects on coast of South India and the island coasts. Mud crabs and Lobsters were also found to be feasible by the local The meteorological and hydrographical data have shown that the maximum farmers. wave and current actions are compatible with the best of offshore fish farming  Further, a major project for cultivation and processing of seaweeds has equipment. Wave conditions in the Arabian Sea seemed to be little rougher than in been recently started in the south east coast by a private company. Bay of Bengal. The water quality conditions along the coast were found to be  Although molluscs culture has been primarily at sustenance level by the stable and good except in the west coast during the south west monsoon, during local fisherman, attempts have been already made for organized culture of which upwelling is a common phenomena, creating oxygen depletion zones, mussels, oysters, clams, etc in some coastal villages. followed by algal blooms which can adversely affect farming operations. The  But such projects faced serious marketing problems due to limited availability of suitable sea and land areas, service, transport facilities etc, were production levels. Besides, so far there has been no system in India to generally found to be adequate except in remote island locations. On the basis of classify suitable water for shellfish culture on account of water quality and this survey it was concluded that about 2000 sq. km. of sea surface is ideally quarantine measures to meet international product standards. Hence, more available to take up offshore farming and a production potential of 8 million efforts are required in this direction. tonnes of high quality marine fish is harvestable through cage culture practices. 1.3.4. Diversification of Coastal Aquaculture – MPEDA’s initiatives 1.3.5. Conclusion Shrimp remains as the single largest and maximum value earner among the The contribution of aquaculture sector is expected to rise from the current seafood exported from the country. It is estimated that cultured shrimps constitute level of US $ 0.7 billion to about US $ 1.5 – 2.0 billion. There is a growing 63% of the quantity of shrimps exported from India. Therefore, in order to demand for marine finfish, and offshore fish farming can offer new vistas for India diversify the export basket, the Marine Products Export Development Authority in aquaculture not only to achieve the set target for national economic (MPEDA) has set out on an action-oriented plan during the next five years. The development but also to ensure livelihoods to many more people. This calls for a plan envisages increasing the share of non-traditional cultured varieties to about positive strategy to formulate policies conducive for development. Sustainable 50% of the total production from aquaculture. In order to concentrate on the development and progress of marine farming requires substantial building of skills 7 in health management and market diversification as key issues, in addition to Backwaters. Seed abundance has been reported during June-August in Tuticorin smooth flow of finance. Concerted efforts from all sides may lead to such and October-January in Chilka Lake. developments in the imminent future. Lobster seed resources- 1.4. Seed resources of finfish and shellfish Detailed studies on the distribution of lobster seed resources in different coastal Coastal waters such as estuaries, mangroves and backwaters serve as nursery areas are lacking. Lobsters spawn throughout the year in deeper waters. Peak grounds for a number of fish and shellfish from where seed of desirable species breeding is during November to December. can be collected using different type of gears. Abundant seeds of cultivable fish Molluscan seed resources and shellfish are seasonally available at various locations in India. Mussel seed - 1.4.1. Finfish Seed Resources The spats of green mussel Perna viridis are found both along the east and west Mullet seeds: coast of India. Gthey are found in rocky open coasts, harbours and mouth of Generally mullet fry are abundant in shallow coastal waters, estuaries, tidal creeks, estuaries where the salinity is as much as that of the seawater. They attach tidal canals and lagoons. They are available throughout in different locations in themselves to rocks, pilings and other hard objects from intertidal zone to a depth Indian coastal waters. of 15 m depth. Milfish seeds: The spats of brown mussel Perna indica have restricted distribution. They are abundant from quilon to Cape Comorin in the south west coast and from Cape The seed of milkfish are available in both the east and west coast of India. In Comorin to Tiruchendur in the south east coast of India. the east coast they are available at Vishakapatanam, east Godavari, Krishna, Guntur and Nellore in A.P, Chinglepet, Chennai, south Arcot, Tanjore, Ramnad Edible oyster seed - and Tirnelveli in T.N. In the west coast they are available from Malabar to the The spats of Crossostrea madrasensis are abundant in Deltas of Godavari and coast of D.K and Udupi dist. Krishna, Pulicat, Chennai, Porto Nov, Mandappam, Keral and Port Blair. The spat Generally they are abundant during APR–JUN and occasionally in OCT – DEC. are available in the south east coast from late September to early May. The distribution and seasonal abundance of some important cultivable species is Pearl oyster seed - shown in the following animation. The seeds of pearl oyster are very scanty and are not available in sufficient quantities. Aquaculture of this group needs to depend solely on hatchery produced 1.4.2. Shellfish seed resources seeds. Shrimp seed resources: Although 11 species of shrimps are available in India only three species namely, Penaeus monodon, P. indicus and P. semisulcatus are cultivable.These species breed in offshore waters, but their seeds enter lagoons, creeks, estuaries and backwaters from where they can be easily collected. The following table lists the occurrences and abundance of seeds of the two most important cultivable species of shrimps. Factors affecting shrimp seed abundance- Tidal amplitude, lunar phases, current, water depth, river discharges, rain, substratum, suspended matter, pollution etc. affect the availability of shrimp seed. P. monodon has wider salinity tolerance, therefore, available in a wide variety of habitats. The seed are particularly abundant during full moon and new moon night tides. Crab seed resources- The seeds of mud crab, Scylla serrata have a wider distribution in the east rather than the west coast of India. They are available in Sundarbans, Chilka lake, Vizag, Pulicat, Parangipettai and Tuticorin. In the West coast they are available in Cochin 8  UNIT 2 - TRAITS OF IMPORTANT CULTIVABLE SPECIES mullets grow quickly in ponds attaining up to 45 cm in length and 750 g in weight 2.1. Grey Mullets at the end of one year. Life span is 2-3 years with maximum growth in the first Introduction year of their life. Grey mullets are important cultivable fishes in brackish water ponds. Their culture 2.2. Milkfish dates back to ancient times. Egyptians had devised their culture methods about Introduction 2500 years ago. In Rome, mullet culture was profitably practiced since the first The milkfish, Chanos chanos is one of the most ideal fish for coastal aquaculture. century. This commercially very important fish has many traits essential for culture. They Grey mullets are suitable for farming because they are herbivores and detritivores, have fast growth rate, in the first year of its life; wide range of tolerance to feeding low in the trophic level. They require less supplementary feed. They are temperature, salinity and dissolved oxygen; feeds on algal mats at the bottom and tolerant to higher temperatures and salinities, hence can be grown in tropical and resistant to most diseases and parasites. sub-tropical areas. They are generally polycultured with other fish and shrimps. It is cultured on a large scale in Indonesia, the Philippines and Taiwan for centuries. It is much esteemed fish in the south east Asian countries. Distinctive characteristics Grey mullets belong to the family Mugilidae. They have a broad and flattened Distinctive characters head, a small and terminal mouth, two short dorsal fins and they are devoid of a Milkfish has a moderately compressed, spindle shaped elongated body covered lateral line. When alive they have blue, green or olive colorations on the back. The with small scales. Mouth is small, without teeth, snout is longer than the lower sides and belly are silvery and body has 3-9 longitudinal streaks. Among the 14 jaw, which has a small tubercle at its tip. species only some are cultivable. Mugil cephalus is the fastest growing larger sized The dorsal fin is located at about the middle point of the body; anal fin short and mullet which is very widely distributed in the tropics and the subtropics. Other situated far behind the dorsal fin base. Lateral line is present and tail fin is large important cultivable species are Liza macrolepis and Liza tade. and forked. The dorsal, anal and caudal fins have dark margins. Mugil cephalus has a robust body and fatty tissue covering most of the eye. Biology The lips are thin, the lower one having a high knob on the symphusis. There are 6- 7 indistinct brown bands down the flanks and a dark purple blotch at the base of It grows up to 180 cm in length and 20 kg in weight, but the fish caught in the sea the pectoral fin. This fish grows to a maximum size of 90 cm, but the common normally range from 70-110 mm. sizes range from 35 – 45 cm. The fry and fingerlings feed on microscopic algae. The fish grows to about 50 cm Liza macrolepis has a moderately robust body and the fatty tissue is only in in length weighing 500 – 800 g in brackish water ponds. the from of a rim around the eye. The body does not have nay bands or stripes. It In ponds milkfish feed mainly on filamentous algae at the bottom along with grows to a maximum size of 60 cm, with common sizes ranging from 25-30 cm. associated microorganisms and detritus. The fish can be fed supplementary feed In Liza tade the body is slender and elongate. The head is depressed and elongated. such as rice bran, oil cakes and other feed stuffs. In adults 5-7 indistinct longitudinal marks are present on the upper half of the 2.3. Pearlspot body. The pearlspot Etroplus suratensis is an important cichlid fish distributed in India, Sri Lanka and Pakistan. It is found in estuaries, tidal creeks, lagoons, backwaters Biology and swamps. It attains a length of more than 30 cm and weight of about 1.5 kg. Majority of grey mullets are marine, inhabiting shallow areas of the sea. Since they are highly eruyhaline and eurythermal, they ascend brackish waters, bays, creeks, Distinctive characters swamps and estuaries. Body is oblong, compressed and elevated. There are small teeth on jaws, none on the palate. The dorsal fin is single, with spinous portion greater in extent than the The adults feed on algae, diatoms, crustaceans, decaying organic matter and soft portion. Lateral line present in the upper fourth of the body. Colour light detritus found at the bottom. The post larvae, fry and juveniles feed on plankton. green, with eight oblique bands on the body. Most of the scales have central white Most species spawn in the sea, but fry form shoals along the coasts and enter pearly spots. The dorsal, caudal, ventral and anal fins are dark coloured, pectoral estuaries, lagoons and creeks from where they can be easily collected. Cultivable yellowish with a black base. Strong spines on dorsal and anal fins present. 9 Biology 2.5. Groupers It matures within one year of its life and breeds in confined waters such as ponds, Groupers are an important group of fishes for coastal aquaculture. Epinephelus almost throughout the year. Natural breeding grounds have weeds with water tauvina and E. malabaricus of the family serranidae have robust, somewhat depths ranging from 50-100 cm. A female releases up to 6,000 eggs at a time. The compressed, oval-oblong and elongated body. There are 11 spines and 14-16 soft eggs are attached to submerged objects like stones, twigs, tiles, bamboo poles etc. rays in the dorsal fin and 18-20 rays in the pectoral fin. by the female after cleaning them. The male fertilizes the eggs and the female A large blackish blotch is present at the base of the last four dorsal spines guards over them during development and hatching. extending on to the lower part of the fin in E. tauvina but absent in E. malabaricus, The early fry feed on zooplankton, the advanced fry on aquatic insect larvae. which possesses about five, more or less distinct and slightly oblique, irregular Juveniles and adults feed on filamentous algae and other weeds. Since this fish is bars on the body. Also, three dark blotches are present on the inter-opercle in E. easy to breed and a herbivore, it is one of the ideal species for coastal aquaculture. malabaricus. 2.4. Asian seabass The head and body are grayish, covered with small, dull, orange-red to dark brown The Asian sea bass Lates calcarifer is a prime value fish grown for luxury markets. spots. They grow to 50-65 cm and to 100 cm respectively. Hong Kong, Thailand, It is commonly distributed in Australia, Myanmar, India, Indonesia, Malaysia, the Singapore and Malaysia are the major producer of groupers in sea cages. Philippines, Singapore and Thailand. This fish can grow in freshwater, brackish Groupers are suitable for culture in net cages, as well as in ponds. Limited success water and marine waters. In India it forms a by catch in the traditional shrimp has been achieved in the hatchery production of groupers. Wild seed collection is filtration fields. This fish is grown in large scale in Singapore and Taiwan in sea the major source of seed for culture of groupers. cages. 2.6. Snappers Distinctive characters Lates calcarifer belongs to the family Centropomidae. It has an elongated and The snappers are also an important group of marine fish that have high value in the compressed body, with a deep caudal peduncle. Head is pointed with a concave domestic and international markets. Of the many species of snappers the Golden dorsal profile, becoming convex in front of the dorsal fin. Mouth is large, slightly snapper or red snapper are the preferred species. Lutjanus johni is culture in oblique and the lower edge of the opercle is serrated, with a strong spine. Malaysia and Singapore. The spinuous and the soft parts of the dorsal fin are separated by a deep notch. The It has a moderately deep body with a straight or slightly convex head profile. The lateral line extends on to the tail. In juveniles the colour is olive brown above with dorsal has10 spines and 13 to 14 soft rays. Longitudinal scales above the lateral silvery sides and belly, while, in adults it is greenish or bluish above and silvery line are parallel to the dorsal fin and those below the lateral line are horizontal. below. No spots or bars are present on the body. The eyes are bright pink, glowing The body has a reddish or bronze – silvery colour with a dark spot on each scale, at night. forming a series of dark streaks in the body. A large black blotch may be present Biology above the lateral line in the junction between spinuous and soft part of the dorsal. The fish has wide range of tolerance to temperature and salinity. Grows to a The fish grows to a maximum length of about 70 cm; but the common sizes are 40 maximum size of up to 200 cm. Common sizes are 25-100 cm. It is a highly – 60 cm in length. carnivorous fish, feeds on fishes and crustaceans. Fry feed on zooplankton and Red snapper feeds on invertebrates and fishes; and inhabits shallow waters and fingerlings on crustacean, worms, molluscs etc. Growth is faster in the first three mangrove areas besides the sea up to a depth of about 80 m. months of the first year. The red snapper is cultured in net cages in the sea; the methods for its culture are For breeding, fish migrate to estuaries. They spawn in different parts of India in similar to that of the Asian sea bass. different months. 2.7. Shrimps In culture ponds the Asian sea bass attains 1.5 to 3.0 kg in the first year and 5 kg in Shrimps are the most widely cultivated marine/brackish water species in India. the second year. The fish is highly cannibalistic. Therefore it is suitable for grow Among edible crustaceans, shrimp are considered as highly valuable commodity. out in floating cages with periodic size grading. They are produced mainly for export purpose although local demand in the coastal areas exists. Shrimps catches from the wild has been stagnating since 1990s. 10 Interest in the culture of shrimps started in the 1990s in India due to high export Penaeus semisulcates potential and apparent high profits of the Industry. It is commonly called green tiger shrimp. It is found in large quantities in the Gulf The shrimp Industry of India is spread over the entire coastline. At present India is of Mannar and Palk Bay. Minor fishery exists in Gujrath, Kerala and Andhra 5th in aquaculture production of shrimps in the World. Pradesh. Juveniles of this species are not found in estuaries unlike the other cultivable shrimps of India. The shrimps prefer shallow areas of the sea where Although Indian shrimp industry is supported by many species, only a few of them luxuriant growth of sea grass is found. Matures at a size of about 130 mm and are suitable for aquaculture on account of their traits suitable for aquaculture. Due breed almost throughout the year. to its large size and faster growth rate, Penaeus monodon is the most widely grown shrimp in India and south east Asia. Other suitable species for culture in India are 2.8. Lobsters P. indicus, P. merguiensis and P. semisulcatus. P.japonicus is grown in Japan Among marine crustaceans, lobsters are the most highly priced commodity of while P. vennamei is the most widely cultivated species in the south and central significant interest in many countries. Supply of lobsters to domestic and America. international market comes mainly from the capture fisheries through intensive fishing in different parts of the world. Traditional lobster stocks are heavily over Penaeus monodon fished. Therefore aquaculture of this group in a necessity. However, aquaculture of This also called as tiger shrimp. This the largest of the marine shrimps. Attains a this group is yet to take off due to very slow growth rate and difficulty in maximum length of 365 mm and 440 g in weight. Found throughout the coast of producing seed in hatcheries due to very poor survival. India. Maximum abundance in the north east coast of India. Juveniles and sub- adults are found in estuaries, backwaters and mangrove areas while mature adults Presently undersized lobsters caught by fishermen are collected by the growers and are caught from the sea. cultured in suitable enclosures to marketable size through appropriate feeding schedule and water quality management. This kind of practice is called fattening. Can tolerate very low salinity. This is the fastest growing hardy shrimp, therefore This is successfully practiced in countries like Japan, Taiwan New Zealand. suitable for aquaculture. In India currently no commercial lobster fattening or culture is being undertaken. Attains maturity at about 200 mm size. Spawning takes place at depths between 30 With the increase in prices for small and medium sized lobster, prospects for and 60 m. Fecundity is 2- 19 lakh eggs at a size range of 200 to 260 mm. lobster culture in India appear to be bright. Bigger species of lobsters such as P. Penaeus indicus homarus and P. ornatus are the suitable species for culture. Following are the traits Commonly known as Indian white shrimp. Distributed from Goa to Kanyakumari of the above species. on the west coast and throughout the east coast. Grows to maximum size of 230 Spiny lobsters are heterosexual and strictly marine throughout their life. They mm. Juveniles are caught extensively in estuaries, adults are found in the sea. attain maturity at the age of two and half years and reproduce in inshore waters. Requires higher salinity than P. monodon in culture ponds. Breeding is continuous, each species having peaks at different times in different Attains maturity at about 130 mm size. Spawning takes place in deeper waters. areas. Matures in ponds. Fecundity is 68000 to 73000 eggs per individual. The life cycle involves a prolonged metamorphic phase extending for several Penaeus merguiensis months. Fertilized eggs attach to the abdomen of the mother which is called The banana prawn P. merguiensis has a discontinuous and restricted distribution berried female. They hatch into a flat transparent phyllosoma larvae. The pelagic along the Indian coast. It is found South of Maharashtra to Goa and North larvae after a series of stages during the next 10-12 months transform in to Karnataka along the west and in Andhra Pradesh and Orissa on the west coast. characteristic post larvae called puerulus. The puerulus is tiny and transparent but resembles adults and settles to the bottom. It soon develops into a juvenile. It grows to a maximum size of 240 mm and attains maturity at a size of about 140 mm. On an average it produces about 4.5 lakh eggs per spawning. The lobsters are carnivorous and nocturnal. They feed on a wide variety of bottom dwelling organisms and decaying animal matter. The most preferred food The juveniles are found in the estuary but adults migrate to sea for maturity and is bivalve mollusks, polychaets and fish. Growth is relatively faster in the early spawning. However, it readily matures in captivity. Juveniles grow faster in stages and they attain 20 – 25 cm in the first two years, thereafter the growth rate brackish waters. is very slow being 2-3 cm per year. They have a life span of 7-8 years 11 Panulirus polyphagus Scylla tranquibarica It attains a maximum body length of about 37 cm. Carapace rounded and This is the larger of the two species growing to a maximum size of 2.0 kg. Free moderately curved with spines and tubercles. Antennular plate with a single pair of living unlike S. serrata which burrows into the substratum. anterior spines. Abdomen without groves. Body colour dull greenish. Each Outer margin of carpus of chelipeds with 2 sharp spines. Colour of upper surface abdominal segment with a distinct transverse band of white colour along the of body light to dark green. Polygonal marking on all walking and swimming legs. posterior margin. Legs with indistinct blotches and short stripes. Scylla serrata It is generally associated with muddy sea bottom and found in maximum Outer margin of the carpus of cheliped with one blunt spine. Colour of the abundance along Maharashtra and Gujarat coast carpapace greenish brown to ferruginous brown. No polygonal markings on legs. Panulirus homarus Lower surface of the fixed finger of cheliped dark to pinkish red in colour. Medium sized lobster growing to about 30 cm in length. Carapace rounded with numerous spines. Antennular plate bearing two equal pairs of spines and many scattered smaller spines in between. Abdominal segments grooved transversely, grooves sometimes interrupted UNIT 3 - METHODS OF COASTAL AQUACULTURE AND medially. Colour of body dark greenish to blackish. Lateral border of each MARICULTURE abdominal segment with a white circular spot. 3.1. Pond culture This species coexists with P. ornatus in the rocky coastal areas from Trivandrum to Cape Comorin, Gulf of Mannar and Madras. P. homarus is dominant in Many species of fish and shrimp are grown in earthen ponds. This is the most southern areas, while P. ornatus is dominant in Mandapam area. popular system of aquaculture particularly in the developing countries. Proper site selection, designing and construction of ponds is necessary for successful Panulirus ornatus operations. The largest species under this genus, grows to about 50 cm. Carapace rounded and covered with numerous spines and tubercles. Antennular plate bearing two pairs of 3.1.1. Site Selection spines, the anterior pair being much larger than the posterior. Abdominal segment  Selection of right site is probably the most important factor determining the smooth, without transverse grooves. Body colour grayish brown. Each abdominal feasibility of viable operations. Many farms laid out on poor sites have been segment with a broad dark transverse band and two large white spots on either abandoned after considerable investment of money and effort leading to heavy side. Legs with black and light yellow stripes. losses. However, ideal sites may not be always available and some 2.9. Crabs compromises may need to be made. Among marine crustaceans, crabs rank third in their importance as gourmet food  Selection of site is generally based on species to be cultured and technology to and the value of fishery they support after shrimps and lobsters. be adopted. However, some factors are common to all sites such as, agro- climatic conditions, access to hatcheries/ seed centres, roads and Out of the 16 species of the crabs exploited through capture fisheries, Scylla communication, access to markets, protection from natural disasters, tranquibarica and Scylla serrata are the larger ones attaining sizes of 0.5 to 2.0 kg availability of skilled and unskilled labour, public utilities etc. and suitable for culture. They are known as mud crabs, green crabs or mangrove crabs. Both these crabs co-exist in the inshore sea, estuaries, backwater, coastal  All available meteorological and hydrological information needs to be lakes and mangrove swamps of all maritime states of India, Andaman and Nicobar collected. Soil characteristics, quality and quantity of available water, ease of Islands. filling and drainage, especially by gravity, are basic considerations. They prefer muddy and sandy bottoms. They breed in the sea and migrate to the  Land elevation and flood levels have to be ascertained. The maximum flood estuaries, megalopa onwards. Males are bigger than females of the same age. They level in the last 10 years and the highest astronomical tide should not be higher are omnivores feeding on shrimps, bivalves and fish among other food items. They than the normal height of the dikes. It will be advantageous to select land with are continuous breeders with peaks at different times in different places. slopes not steeper than 2 percent. The area should be sufficiently extensive to allow future expansion and preferably be of regular shape to facilitate farm design and construction. 12  Among other important general factors be considered are the existing and 3.1.3. Design and Construction of coastal ponds future source of pollution, developmental plans for the neighborhood areas and  The design of the farm and its construction are as important as the legal and social aspects of farm establishment. The possible effects of the selection of the site in ensuring success of the project. As indicated earlier discharges of the farm on the environment needs to be considered. This can ideal sites may not always be available. Deficiencies in sites have to be greatly influence the attitudes of the local communities to the proposed made up by suitable designs for construction and operation. farming and hence their future cooperation.  As pond farm design is so site-specific, one cannot conceive of a design  Sites generally available for the coastal pond farms are tidal and inter-tidal that can be of universal use. However, some major design feature can be mud flats in protected areas of near estuaries, bays, creeks, lagoons and salt defined on the basis of the site physiography, the source and nature of the marshes. If the ponds need to be supplied water through tidal flow and water supply, type of stock enclosures to be used, organisms to be cultured information on tidal amplitude at the site is essential. and the techniques of management.  Data on high tides and low tides need to be collected from tide charts available  For designing coastal pond farms the most important data needed are the of the nearest port. The elevation of the land relative to the tides is important seasonal variation in salinity of the available water and access to fresh to decide on the type of ponds to be constructed (whether tidal fed or pump water to reduce salinity when required. When ponds have to be filled with fed) and amount of excavation necessary for constructing the ponds. tidal energy, detailed studies are needed to determine the stage/duration/  The construction of ponds in areas reached only by the high spring tides would frequency relationship necessary for engineering designs. require excavation, leading to high cost of construction. For tidal fed ponds  For designing proper water management in the tide fed ponds, it is sites with elevation of between 0 and 140 cm relative to tides is necessary. necessary to determine the ground elevation, which actually approximates However, if tidal energy can be replaced with other forms of energy the above the tidal levels of mean lower high water or mean high water at neap tide. limitation would not apply. It is uneconomical to excavate more than 50 cm for pond construction. If 3.1.2. Criteria to locate a good coastal farm site this is needed it will be better to resort to pumping rather than depend on 1. Average air temperature of 260 C for tropical fish and crustaceans tides for water supply and drainage. 2. Average pond temperature of 300 C.  As mentioned earlier pond farm designs are site specific. The aquaculturist 3. Salinity of 10 to 35 parts per thousand (1.0 to 3.5%) - optimum would depend has to work closely with the engineer to arrive at an economically acceptable design that will meet the operational requirements of the on the species selected for culture. species and the culture technology. 4. Brackish/seawater of good quality and high natural productivity- optimum water quality will depend on the species to be cultured. Size and shape: The size of a farm has to be determined based on a number of factors such as 5. Away from all sources of pollution (urban, agricultural and industrial). quantity of water and extent of land available; technology to be followed 6. Availability of seed for stocking (extensive, semi-intensive or intensive farming); and production and income 7. Land of suitable elevation to enable easy drainage of water from the ponds required to make the operation viable. 8. Clay or clayey loam soil 3.1.4. Water Supply Systems 9. Soil with relatively higher pH (>6.0)  Proper water management in one of the most important factors that 10. Good electricity connection and supply governs the success of aquaculture operations. Not only water supply, but 11. Good availability of labour also drainage system should be designed and constructed properly to get 12. Road and transportation good production. 13. Availability of communication  The quantity of water required for ponds will depend on the soil and 14. Availability of supplies climatic conditions. The quantity of water will also depend on the type of 15. Proximity to markets technology to be used and species being cultured. Intensive farming 16. Low flood risk requires more water than extensive farming per unit area. 13   The water supply and drainage systems have to be designed properly to  Reasonably sheltered areas, with sufficient water movement to effect convey the required quantity of water. Different designs have been adequate mixing and aeration are selected as sites for cage farms. adopted, based on different criteria and requirements.  The occurrence of typhoons, hurricanes and cyclones in the area and the  It is essential to have separate supply and drainage canals as well as vulnerability of the sites are also major considerations in the design of separate inlets and outlets for operational safety and efficiency. Inlets and cage farms. Polluted sites are generally avoided. outlets should be located on opposite sides. Outlets should also facilitate  In cold climates, areas that receive safe heated water effluents are harvesting of the produce. preferred, as higher water temperatures generally improve growth and  A coastal shrimp/fish farm generally has main and subsidiary canals for productivity. water supply and drainage.  Unused feed and fish faeces fall from the bottom of floating net cages on  There are many types of water control structures. The inlets may be to the floor of the waters bodies. Accumulated wastes decompose and anything from a simple pipe to concrete sluice gates. A turn down pipe or cause oxygen depletion or generation of methane or other toxic gasses a sluice gate is used for outlets. Sluice gates have slots for fixing screens under anaerobic conditions. or barrier planks.  Cages also increase deposition of silt on the bottom of the site. It is  Water can be supplied either by tidal energy or by pumps depending on therefore necessary to have enough movement of clean water below the the design of the farms. Drainage is by gravity; therefore ponds must be floating cages. Carrying capacities of the areas should be determined to designed accordingly. avoid overcrowding of cages.  You will learn more about it in you course on 'Fish Farm Engineering.  The most sophisticated design of cages is use in cage farms of Norway 3.2. Cages where salmon are grown extensively. Cages of size 100 to 500 m3 are used. A simple unit holds a net of four vertical sides and is rectangular in  Rearing fish in cages is a traditional practice in some Asian countries. It cross section. The more popular ones are circular in cross section. appears to have originated in Kampuchea two centuries ago. It has spread to other places in more advanced form recently.  There are many ways of arranging cages in a cage farm. Where possible, it is preferable to moor cages to a jetty with direct access to a quay, in order  Salmons in Norway, yellow tail in Japan and groupers and sea bass in to facilitate work and reduce labour cost. Hong Kong, Vietnam and Singapore are grown in cage farms.  However, environmental and site conditions may require them to be  Cages offer great opportunities for aquaculture in open waters of the seas. located farther away from the coast, in which case a work boat will be In recent years cage aquaculture has become a major source of aquaculture needed for access. Cages should be installed on the sides of a central production, particularly of high value fish like salmon, trout, sea bass and walkway to facilitate day to day work on the farm. groupers. Several types and designs of cages and cage farms have been developed and commercially used.  Feed dispensers are installed above each cage; in others, manual feeding is done. Mooring blocks have to be sufficiently heavy and are usually made  Majority of the cages consist of a floating unit, a framework and a flexible of concrete with heavy galvanized bolts. mesh net suspend under it. The floating unit can consist of empty barrels, Styrofoam polyethylene pipes, or ready made pontoons of plastic or metal.  Most of the presently available cages are designed for use in protected bays and fjords. In order to utilize more open waters and high seas, special  The buoy units are often built into a framework. The framework can be cages with a flexible rubber framework have recently been developed. made of impregnated wood, bamboo spars, galvanized scaffolding or welded aluminum bars. Nylon is commonly used for net, but weld-mesh or 3.3. Pens even woven split bamboo is also used. Cage flotillas provide safer  Pens and enclosures are transitional structures between ponds and cages. working conditions and enable storage of feed on site, as well as They are used for culture of yellow tail in Japan, milkfish in the installation of automatic feeders. Philippines and salmon in Norway. 14   The success of pens for culture depends on the hydro-biological conditions Pole /stick culture: Wooden or bamboo sticks are installed in rows in of the site. The design of the structures is based on adequate knowledge of shallow muddy regions of the intertidal zones. Sheltered areas free from water quality, floods, waves and currents and prevalence of predatory strong waves and wood boring organisms are selected. Seed oysters are animals. attached to the poles using degradable nets, or sting on which oysters are  Pens are formed by net barriers to partition off areas of an open water collected are strewn round the poles for fattening and final harvest. body, such as intertidal areas of the sea, bays or lagoons. Raft/string culture: string/trays are suspended from floating rafts or long  Different designs of enclosures have been constructed. Generally the lines. Raft are use in protected areas, strings in more exposed areas. enclosure is formed on one side of the shore and on the other three by a Rafts/longlines are supported by buoys. Trays are made of wood or wire wall of nylon netting hung from pole driven into the bottom. screens. Spat oysters are placed in trays and suspend for grow out.  In many such enclosures, concrete or stone walls are built on each side B. Mussels where it joins the shore or provide adequate support to the nets. The methods for mussels are very similar to oyster culture. Bottom culture is widely practiced in Germany and the Netherlands; stake culture in France, Italy  Around the rest of the perimeter, heavy posts of impregnated timber or and the Philippines; and raft and long line culture in Spain. concrete piles are driven into the bed extending for about 2m out of water all times. C. Seaweeds Raft and long line culture similar to oysters and mussels is practiced for growing  Net barriers may be hung from steel cables stung between the poles or the seaweeds. Spores are collected on nets from areas rich in spores and they are concrete of steel piles. To prevent the lateral move