SYBSc ZOO paper II Notes: Fisheries Chapters 1 to 3

UNIT: 1 FISHERIES

An introduction to fisheries and its types (in brief): Freshwater fisheries, Marine fisheries, Brackish water fisheries.

1.1. Introduction Fisheries

History:

Fishing and aquaculture in India has a long history. Kautilya's Arthashastra (321–300 B.C.) and King Someswara's Manasottara (1127 A.D.) each refer to fish culture.  In Hindu mythology reference of fishes has been mentioned, one of the incarnation of Lord Vishnu is Matsya Avatar, in Navanath puran the names of two nathas are Machindranath and Meen nath. This indicates and suggests the role of fishes in human civilization. Fishing as an occupation is being practiced in India since the time immemorial and has been regarded as a supplementary enterprise of the fishermen community. For centuries, India had a traditional practice of fish culture in small ponds in Eastern India. Significant advances in productivity were made in the state of West Bengal in the early nineteenth century with the controlled breeding of carp in Bundhs (tanks or impoundments where river conditions are simulated). Fish culture received notable attention in Tamil Nadu as early as 1911, subsequently, states such as West Bengal, Punjab, Uttar Pradesh, Gujarat, Karnataka and Andhra Pradesh initiated fish culture through the establishment of Fisheries Departments. In 2006, Indian central government initiated a dedicated organization focused on fisheries, under its Ministry of Agriculture.

Fisheries are a sunrise sector in Indian economy and it has witnessed a spectacular growth of over 800 per cent, from 0.75 Mt to 6.2 Mt during the last five decades. After the mid-1980s, the development of carp polyculture technology has completely transformed the traditional backyard activity into a booming commercial enterprise.

Definitions:

1.       Aquaculture has been defined in many ways. It has been called as the rearing of aquatic organisms under controlled or semi controlled condition - thus it is underwater agriculture. The other definition of aquaculture is the art of cultivating the natural produce of water, the raising or fattening of fish in enclosed ponds.

2.       Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. 

3.       According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats, and purpose of the activities or a combination of the foregoing features". The definition often includes a combination of fish and fishers in a region, the latter fishing for similar species with similar gear types.

4.       Fishing is the activity of trying to catch fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping term fishing may be applied to catching other aquatic animals such as molluscs, crustaceans, and echinoderms. The term is not normally applied to catching farmed fish, or to aquatic mammals, such as whales, where the term whaling is more appropriate.

5.       Fish farming is the principal form of aquaculture, while other methods may fall under mariculture. Fish farming involves raising fish commercially in tanks or enclosures, usually for food.

6.       Mariculture is aquaculture in the saltwater of the sea. It may be in seas, bays, bays, sounds etc. e.g. traditional mariculture in inshore and offshore waters by a large number of countries notably, U.S.A., France, Spain, Japan etc.

7.       Fisheries technology is basically concerned with the development of craft, gear, and processing methods.

8.       A facility that releases juvenile fish into the wild for recreational fishing or to supplement a species' natural numbers is generally referred to as a fish hatchery. Worldwide, the most important fish species used in fish farming are carp, salmon, tilapia and catfish.

Importance of Fisheries:

Most of the protein in the world’s food supply is derived from either grain or animal sources, each of which provides roughly half the supply. Fish resources generally account for about 16% of the protein attributed to the animal group. Fisheries resources are important in following ways.

1)         Fish and crustaceans are important and high quality sources of amino acids, which are nutritionally important types of protein found only in small amounts in cereals and grains. This turns out to be important for global nutrition and particularly important to some food deficient, low-income countries.

2)         Fisheries are locally important sources of food, trade and income in many developed and developing coastal nations.

3)         Trade in fisheries products is an important source of foreign exchange for some countries and has been of growing importance as global markets for both food fish and fishmeal have grown.

4)         Fisheries provide employment and income earning opportunities for considerable numbers of people, particularly in the less developed and employment-scarce coastal countries (Bell, 1978; Delgado et al., 2003).

5)         Fish as food—both from fish farms and catch fisheries—offers India one of the easiest and fastest way to address malnutrition and food security.

6)         Fish flesh, on the average, contains: moisture and oil, 80%; protein; 15–25%; mineral matter, 1–2%; and other constituents, 1%. Water content is known to vary inversely with fat content.

7)         Fisheries are harvested for their value (commercial, recreational or subsistence). They can be saltwater or freshwater, wild or farmed. Examples are the salmon fishery of Alaska, the cod fishery off the Lofoten islands, the tuna fishery of the Eastern Pacific, or the shrimp farm fisheries in China.

8)         Fisheries and aquaculture provide direct and indirect employment to over 500 million people. In 2005, the worldwide per capita consumption of fish captured from wild fisheries was 14.4 kilograms, with an additional 7.4 kilograms harvested from fish farms.

9)         Indian fishery also supports several ancillary activities such as boat building, processing plants etc.

10)      According to FAO statistics, the total number of commercial fishermen and fish farmers is estimated to be 38 million. 

Objectives of Fishery:

 These are:

1. Production of protein rich, nutritive, palatable and easily digestible human food benefiting the whole society through plentiful food supplies at low or reasonable cost.
2. Providing new species and strengthening stocks of existing fish in natural and man-made water-bodies through artificial recruitment and transplantation.
3. Production of sport fish and support to recreational fishing.
4. Production of bait-fish for commercial and sport fishery.
5. Production of ornamental fish for aesthetic appeal.
6. Land and aquatic resource utilization: this constitutes the macro-economic point of view benefiting the whole society. It involves (a) maximum resource allocation to aquaculture and its optimal utilization; (b) increasing standard of living by maximizing profitability; and (c) creation of production surplus for export (earning foreign exchange especially important to most developing countries).

9. Production of industrial fish.

Indian Fishery at a Glance

·         India has 8,118 kilometers of marine coastline, 3,827 fishing villages, and 1,914 traditional fish landing centers. India's fresh water resources consist of 195,210 kilometers of rivers and canals, 2.9 million hectares of minor and major reservoirs, 2.4 million hectares of ponds and lakes, and about 0.8 million hectares of flood plain wetlands and water bodies.  As of 2010, the marine and freshwater resources offered a combined sustainable catch fishing potential of over 4 million metric tonnes of fish. In addition, India's water and natural resources offer a tenfold growth potential in aquaculture (farm fishing) from 2010 harvest levels of 3.9 million metric tonnes of fish, if India were to adopt fishing knowledge, regulatory reforms, and sustainability policies adopted by China over the last two decades.

·         The marine fish harvested in India consist of about 65 commercially important species/groups. Pelagic and mid water species contributed about 52% of the total marine fish in 2004.

·         India is a major supplier of fish in the world. In 2006 the country exported over 600,000 metric tonnes of fish, to some 90 countries, earning over $1.8 billion. Shrimps are one of the major varieties exported. The giant tiger prawn (Penaeus monodon) is the dominant species chosen for aquaculture, followed by the Indian white prawn (Fenneropenaeus indicus). Shrimp production from coastal aquaculture during 2004 stood at approximately 120,000 tonnes. Farmed shrimp accounted for about 60% of shrimp exported from the country.

·         Marine and freshwater catch fishing combined with aquaculture fish farming is a rapidly growing industry in India.

·         In 2008 India was the sixth largest producer of marine and freshwater capture fisheries, and the second largest aquaculture farmed fish producer in the world.  Despite rapid growth in total fish production, a fish farmers’ average annual production in India is only 2 tonnes per person, compared to 172 tonnes in Norway, 72 tonnes in Chile, and 6 tonnes per fisherman in China. 

Growth of Indian Fishery:

It rose from only 800,000 tons in FY 1950 to 4.1 million tons in the early 1990s. From 1990 through 2010, Indian fish industry growth has accelerated, reaching a total marine and freshwater fish production to about 8 million metric tons. Special efforts have been made to promote extensive and intensive inland fish farming, modernize coastal fisheries, and encourage deep-sea fishing through joint ventures. There is an increasing demand for fish and fish protein, which has resulted in widespread overfishing in wild fisheries.

These efforts led to a more than fourfold increase in coastal fish production from 520,000 tons in FY 1950 to 2.4 million tons in FY 1990. The increase in inland fish production was even more dramatic, increasing almost eightfold from 218,000 tons in FY 1950 to 1.7 million tons in FY 1990. The value of fish and processed fish exports increased from less than 1 percent of the total value of exports in FY 1960 to 3.6 percent in FY 1993.

Fish production in India during1990 to 2007, has grown at a higher rate than food grains, milk, eggs, and other food items.

Future:

·            Fish production in India has increased more than tenfold since its independence in 1947. According to the Food and Agriculture Organization (FAO) of the United Nations, fish output in India doubled between 1990 and 2010.

·            The fishery sector is a major foreign exchange earner in the Indian economy. Its foreign exchange earnings have been projected to increase by 16 to 20 per cent by 2005 and 26 to 42 per cent by 2015. In view of higher production in fisheries, producers may lose from price fall in the domestic market; where prices are estimated to fall by 15 to 20 per cent by 2005 and 27 to 54 per cent by 2015. However, the net gain from export has been projected to be substantial; Rs. 16 to 21 billion by 2005 and Rs. 74 to 152 billion by 2015. Nearly 85 per cent of the export benefits are projected from shrimp export alone.

India’s Share in World Fish Production

Fish production in India has touched 5.96 million tonnes in 2001-02 from mere 0.75 million tonnes in 1950-51. The global and Indian fish production during the last 50 years is reported in The share of India in global fish production has grown gradually, from about 2.6 per cent during the 1960s and 1970s to 4.62 per cent in 2000-01 (Table 1.1).

Table 1.1. Fish production in India and world, 1950-51 to 2001-02*

Year	World (million tonnes)	India (million tonnes)	India’s share (%)
1950-51 1960-61 1970-71 1980-81 1985-86 1990-91 2001-02	23.50 43.60 66.20 72.30 85.60 97.97 129.00	0.75 1.16 1.76 2.44 2.88 3.84 5.96	3.19 2.66 2.66 3.37 3.36 3.92 4.62

*Source: Fisheries Statistics, 2000 FAO; Handbook on Fisheries Statistics, 2000, Ministry Of Agriculture, Government of India and unpublished data from Department of AnimalHusbandry and Dairying, Ministry of Agriculture, Government of India.

According to the National Sample Survey (NSS), the annual per capita fish consumption was 2.45 kg in 1983; it increased to 3.45 kg in 1999-2000. Only 35 per cent population in India was estimated to be fish eater and their annual per capita fish consumption was 9.8 kg in 1999-2000. However, wide regional variations do exist in fish consumption across regions, states and income classes.

TYPES OF FISHERIES

Fisheries can be categorized into two types –

        i.            fin fisheries - The former is fisheries of true fishes

      ii.            non-fin fisheries- is the fisheries of organisms other than true fish like prawn, crab, lobster, mussel, oyster, sea cucumbers, frog, sea weeds, etc.

Fin fisheries can be further categorized into two types – Capture fisheries and culture fisheries.

The marine water bodies are used mainly for capture fisheries resources, the inland water bodies are widely used both for culture and capture fisheries.

a)       Capture fisheries- It is exploitation of aquatic organisms without stocking the seed. Recruitment of the species occurs naturally. This is carried out in the sea, rivers, reservoirs, etc. Fish yield decreases gradually in capture fisheries due to indiscriminate catching of fish including brooders and juveniles. Overfishing destroys the fish stocks. Pollution and environmental factors influence the fish yield. The catches include both desirable and undesirable varieties.

Capture fisheries is intended for catching fishes and also prawns, lobsters, crabs, sea-cucumbers, whales, pearl oysters, edible bivalve and copious other organisms of other than fishes etc. Primitive human beings were acquainted with capture fishery centuries passed for him to observe and understand for the possibilities of culturing fish. Then also he depended mostly on the culture of fishes with parental care. Later, he tried to collect the fingerlings in canals, distribution canals. In the earlier days, the mixture of carnivore fish fingerlings and carp fish fingerlings were stocked together in tanks. Later, they were segregated and stocked selecting the required variety. Capture fisheries can be broadly classified as industrial scale, small-scale or artisanal, and recreational.

Capture of fishes can be broadly divided in to two types;

a) Capture by Human effort

b) Capture by observing the behavioural pattern of Fishes.

Fig.1.1. Types of Fishery on basis of fin type

b)      Culture fisheries - It is the cultivation of selected fishes in confined areas with utmost care to get maximum yield. The seed is stocked, nursed and reared in confined waters, and then the crop is harvested. Culture takes place in ponds, which are fertilized and supplementary feeds are provided to fish to get maximum yield. In order to overcome the problems found in capture fisheries to increase the production, considerable attention is being given to the culture fisheries.

Culture fisheries are conducted in freshwater, brackish water and sea waters. With the development and expansion of new culture systems, farming of a wide variety of aquatic organisms like prawns, crabs, molluscs, frogs, sea weeds, etc. have come under culture fisheries. Due to the culture of a variety of aquatic organisms, culture fisheries have been termed as aquaculture.

1.       Fisheries can be mainly categorized according to aquatic resources as

1.       Inland water fisheries

2.      Marine water fisheries

3.       Brackish water fisheries

Fig.1.2. Types of Fishery on basis of Aquatic resources.

While the marine water bodies are used mainly for capture fisheries resources, the inland water bodies are widely used both for culture and capture fisheries.

1.    Inland water fisheries

Meaning: Inland fishery is mainly concerned with canals, ponds, freshwater. India’s vast and varied inland fishery resources, potentially one of the richest in the world, can broadly be divided into two categories, viz, fresh waters and brackish waters. The inland fisheries are of two types: viz, capture and culture and culture fisheries. The management of the capture fisheries, which are provided mostly by the rivers (riverine), estuaries (estuarine) and the large lakes (lacustrine), is directed towards their conservation and planned development for maintaining a continued productivity. Culture fisheries, provided by smaller impounded water such as tanks, jheels, pound, etc, are governed by culture operations relating to their management.

Export/ Production: Inland capture fishery of India has an important place; it contributes to about 30% of the total fish production. The inland sector contributed increasingly (6.2% annually since 1980-81) to the growth of fish production in India (5.21% annually since 1980-81). West Bengal and Andhra Pradesh are leading states in Inland fish production (Fig. 1.5). Table 1.2 mentions the comparative production of Marine and Inland Fisheries from 1950 to 2008.

1.1.1. FRESH WATER FISHERIES

Meaning: Fishery production both capture and culture from fresh water bodies.

Aquatic Resources:

In India, there is in addition to extensive river systems, a large variety and extent of standing inland waters, ranging from the icy cold lakes of the higher altitudes to the tropical fresh water pound of the plains. The freshwater inland water bodies fall into five major categories, distinguished as the Ganga, the Brahmaputra and the Indus system of the Northern India, and the East and the West coast river systems of the Southern (peninsular) India (Fig.1.3 &1.4). These river systems have certain characteristics of their own with respect to their ecology, climatic conditions and fish populations of commercial food fishes.

Inland water bodies include freshwater bodies like rivers, canals, streams, lakes, flood plain wetlands or beels (ox-bow lakes, back swamps, etc.), reservoirs, ponds, tanks and other derelict water bodies, and brackish water areas like estuaries and associated coastal ponds, lagoons (Chilka lake, Pulicat lake) and backwaters (Vembanad backwaters), wetlands (bheries), mangrove swamps, etc.,

Floodplain wetlands or beels are other potential fishery resources in the states of Assam, West Bengal and Bihar. They offer tremendous scope for both culture and capture fisheries. These Water bodies play vital role for recruitment of fish stocks of the riverine system and provide Nursery grounds for commercially important fin fishes and shellfishes. It has been estimated that these beels possess potential to yield as much as 1000-1500 kg/ha/year.

*Source: Hand Book of Indian Fisheries 1951.

Fig.1.3. Major water systems of India.

RESOURCES	LENGTH / AREA
Rivers and Irrigation canal	1,91,024 km(195000)
Ponds and Tanks	2.14 m ha
Reservoirs	3.15 m ha
Upland Lakes	0.72 m ha
Brackish water	1.24 m ha
Flood plain wetland	0.35 m ha
Estuaries	0.3 m ha

• Max total water bodies in states –
• Odisha (9.8 L ha)
• AP (8.11 L Ha)
• Karnataka – 7.4 L ha
• Tamil Nadu – 6.9 L ha
• West Bengal – 5.45 L ha

• RIVERINE FISHERIES
• A river is a natural watercourse usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water.
• 5 Major river systems in India.
• The Ganga, the Brahmaputra, the Indus, the east coast, and the West coast river systems.

·         Production figures from different riverine systems are not available, estimates made for major rivers showed yield varying from 0.64 to 1.64 tonnes per km with an average of 1 tonne per km.

• The important fish species in the northern rivers are:

i) The Carps, Catla catla, Labeo rohita, Cirrhinus mrigala and Labeo calbasu

ii) The Catfishes, Wallago attu, Mystus seenghala, Pangasius pangasius, Eutropicthyes vacha.

iii) The Clupeids, Hilsa ilisha, Notopterus.sps.

iv) The eels, Ophiocepahalus, Anabas etc.

• The fishes seen in the southern rivers are:

i) The carps, Labeo fimbriatus, Cirrhinus cirrhosa, Punctatus dubius. Punctatus dobsoni.

ii) The mahseers, Tor khudree.

iii) The inter-regionally transplanted carps such as Catla catla, Labeo rohita,

Cirrhinus mrigala and Labeo calbasu are also seen in southern rivers.

iv) The tributaries of the Cauvery from the Nilgiris have cold water fishes like the trout and tench.

Fish catch from riverine resources comprises mainly cat fishes and local minor fishes. The important varieties of fishes occurring naturally in the water resources of the are as follows:—

Scientific name	Local name
1. CARPS
FAMILY — CYPRINIDAE
Puntius kolus (Sykes)	Kolshi.
Puntius jerdoni (Day)	Panghat.
Rasbora daniconius (Ham)	Dandwat.
Oxygaster clupeoides (Bl.)	Alkut.
Labeo fimbriatus (Bl.)	Tambir.
Labeo rohita (Ham.)	Rohu.
Cirrhina mrigala (Ham.)	Mrigal.
Catla catla (Ham. Buch.)	Catla.
Chela Sp.	Ambali.
2. CAT FISHES
FAMILY — SILURIDAE
Wallago attu (Bl.)	Shivda.
3. LOACHES
FAMILY—COBITIDAE
Noemacheilus Sp.	Muri.
4. SNAKE-HEADED FISHES
FAMILY — CHANNIDAE
Channa marulius (Ham)	Murrel.
5. SPINY EELS
FAMILY—MASTACEMBELLIDAE
Mastacembelus Sp.	Wambat.

The fishing nets found to be used in the district are known as ' Pagir' or ' Phek Jal', Gill net or ' Phasali Jal' and Drag net or ' Pati Jal'.

PONDS FISHERIES: Ordinary fresh water fish culture ponds are still-water ponds. They vary a great deal in water spread area and depth. Some are seasonal and some perennial. The ponds may be rain fed (also called sky ponds) and/or may have inlet and outlet systems. The water supply may be from a stream or a canal or from an underground source such as wells, tube wells etc. The water receptivity of the ponds depends on soil composition of the pond bottom and subsoil water level. The natural biological productivity of such ponds depends on soil and water qualities.

Fisheries resources: The commercially important fresh water fishery resources are carps, mullets, chanos, and prawns. The freshwater fish species are grouped as follows:

1. Indian Major Carps :   Catla, Rohu, Mrigal, Calbasu
2. Other freshwater fish : Silver carp, Grass carp, Common carp, Murrels, Hilsa (inland), and other unspecified inland fishes
3. Prawn/Shrimp : Penaeid shrimp

•Table1.2. Marine and Inland Fish production in India (‘000 Tonnes)*

Year	Marine	%Marine	Inland	% Inland	Total
1950-51	534	71.01	218	28.99	752
1980-81	1555	63.68	887	36.32	2442
2007-08	2920	40.97	4207	59.03	7127

*Source: Inland Fisheries sector in India 2008 Mr. Omprakash et al.

1.1.2. Marine water fisheries

The country gets marine fishery products mainly from coastal seas, offshore and deep sea resources.

Meaning: A marine fishery is that branch of fisheries which deals primarily with marine fishes and other sea products.  Close to 90% of the world’s fishery catches come from oceans and seas, as opposed to inland waters.

Aquatic Resources: India has a long coastline of resources in terms of an 8,129 kms0.5 million sq. km of continental shelf. Its marine resources are spread over in the Indian Ocean, Arabian Sea, and Bay of Bengal. The two main seas, the Bay of Bengal ( the eastern or Coromandel coast) and the Arabian seas (the west or Malabar coast)  because of physico chemical, biological, climatic and oceanographically variations  shows difference in varieties and quantity of  marine fishery resource. The north east monsoon winds and rain are moderate, flows for short duration over Bay of Bengal. The southwest monsoon winds and rain are stronger and longer sweeps over Arabian seas. The Somali ocean currents coming from Africa also sweeps over and near the head of Arabian Sea. Because of this the plankton (which is a source of food to fishes) production is higher in Arabian Sea than Bay of Bengal and hence fish production is more from west or Malabar Coast. The exclusive economic zone (EEZ) of the country has an area of 2.02 million sq km comprising 0.86 million sq km on the west coast, 0.56 million sq km on the east coast and 0.6 million sq km around the Andaman and Nicobar islands. It is only after the establishment of Central Marine Fisheries Research Institute in 1947.

The east coast supports activities such as agriculture and aquaculture while a number of industries are supported on the west coast. Tourism has emerged as a major economic activity in coastal states such as Goa, Kerala and Orissa. Haryana and Gujarat are leading states in Marine fish production (Fig.1.4).

Fisheries resources: The commercially important marine fisheries resources are oil sardines, mackerels, Bombay ducks, tunas and the prawns. Other marine resources are the catfishes, polynomids, pomfrets, crabs, oysters, marine algae, etc.

Classification of marine fish species

The marine fish species are grouped as follows:

1. Pelagic fishes– high-value (PHV): Seer fish, oceanic tunas (yellow fin tuna, skipjack tuna), large carangids (Caranx sp.), pomfrets, pelagic sharks, mullets.

Fig. 1.4.  Indian Map showing Aquatic resources and Fishery Area

2. Pelagic fishes – low-value (PLV): Sardines, mackerel, anchovies, Bombay duck, coastal tunas, scads, horse mackerel, barracudas
3. Demersal fishes – high-value (DHV): Rock cods, snappers, lethrinids, big-jawed jumper (Lactarius), threadfins (Polynemids)
4. Demersal fishes – low-value (DLV): Rays, silver bellies, lizard fishes, catfishes, goat fishes, nemipterids, soles
5. Crustaceans – high-value (Shrimp): Shrimps, lobsters
6. Molluscs and others (Molluscs): Cephalopods (squids, cuttlefishes and octopus), mussels, oysters, non-penaeid prawns, etc.

 Export/ production: The west coast is intensively fished producing more than 70% of the total catch of fish, while the east coast is sparsely fished, giving 30% only. Fisheries in the Indian marine environment comprise 15 pelagic and the same number of demersal fisheries. India is a major seafood exporting country. The annual export of fisheries is 0.4 million tonnes (mt) worth Rs 47,000 million (Pandian, 1999). Marine fishery exports in 2000 were 421,075 metric tonnes valued at Rs 63,965 million. The Indian marine production increased from 0.534 mt in 1950-51 to 2.576 mt in 1992-93. However, the growth of Indian marine fisheries has become sluggish in recent years (Acharya and Thakur, 1999) and reached a plateau at around 2.8 million tonnes by 1995-96 (MoA, 1996). The growth in marine food production decreased to 2.5 % during 1990-99 from 3.73 % during 1980-90 (Krishnan Birthal, Pounusamy et al-2000). The potential harvestable yield of marine fish stock in the Indian EEZ is estimated to be 3.9 million tonnes (Devaraj and Vivekanandan, 1999; Somvanshi, 1999). About 1 million people in 3651 villages of India situated along the coast are employed in marine capture fisheries. Table 1.2 mentions the comparative production of Marine and Inland Fisheries from 1950 to 2008.

 Fishing methods: Marine fish are caught using fishing nets and fishing boats. Yields are increased by lococating schools of fish in the open sea using satellites and eco-sounders. As marine fish stocks get depleted the demand for more fish is met by culture fisheries also called mariculture.

The marine fishery resources have been broadly divided into three categories:

a) Coastal Fishery or Inshore Fishery.

b) Offshore Fisheries, and

c) Deep Sea Fishery.

            In India, the inshore area may be defined as the area between 0-10 fathoms line. Offshore area is between 11-40 fathoms, and the deep sea area lies beyond 40 fathoms. Coastal fishing or inshore fishing is generally limited to 11 to 16 km. wide. Coastal waters having a total continental shelf area of 2, 59,000 sq.km. Along the 5650 km. long coast line. Twelve bio-geographical zones are distinguished along the coast line : i) Kerala and South Malabar, ii) Malabar and South manor, iii) Konkan iv) Bombay and Gujarat, v) Kathiawar, vi) Palk bay and Gulf of Myanmar, vii) Coromandel south, viii) Coromandel north, ix) Andhra  south, x) Andhra middle, xi) Andhra north and xii) West Bengal and Orissa.

Coastal fish, also called offshore fish or neritic fish, inhabit the sea between the shoreline and the edge of the continental shelf. The continental shelf is usually less than 200 meters deep. Off shore fishing comprises gill net operations in surface and mid-waters, lining conducted from Mother-ship operations and trawling in bottom waters. Trawling has proved the most efficient fishing method. The catch rate with trawling ranges between 300 kg. /fishing hour to 600 kg/fishing hour.

The greatest success made in recent years in deep sea and off shore fishing stemmed from mechanization of indigenous crafts, i.e. installation of engines for propulsion and use of mechanical devices in operating the gear, and introduction of new types of mechanized crafts and gears with full modern accessories and facilities.

 ‘Deep Sea’ can be divided into three parts. The region between 200-1000 meters is called the ‘Mesopelagic’ zone, where the light gradually fades, and temperature is in between 4-8⁰ C. The part of the ocean below 1000 meter is called ‘Bathypelagic’ zone, and the deepest part characterized by complete darkness forms the deep water ‘Benthic’ zone. A large number of species of fish inhabit the deep sea, and majority of them belong to the orders Anguilliformes (eels), Notacanthiformes (spinly eels), Stomoiiformes (bristle mouths, hatchet fishes, viper fishes, dragon fishes etc.), Myctophiformes (lantern fishes, barracudas), Gadiformes and Lophiformes (angler fishes).

Deep-sea fishing is possible in the off shore waters of Kerala, Bombay, Karwar, Calcutta, Porbander, Dwaraka, Mangalore, Cannanore, Cochin etc. The Dwaraka region is the richest region as it yields the maximum number of fishes. The important offshore and deep-sea fishes are, the Indian Salmon, giant head fin, Jew fish, Pomfrets, and rays. The most important bony fish are various species of perches. The Pristis and Carcharhinus are the important cartilaginous fishes.

Fig.1.4 a. Deep Sea Mesopelagic fishes (a) Cholirodus, b) Malacosteus, c) Argyropelecus.

Marine Fisheries Resource Management: It includes following steps-

• Intensification of exploitation in offshore grounds.
• Enhancement of coastal stocks through sea ranching.
• Creating of artificial fish habitats in the inshore grounds.
• Regulation of fishing efforts, effort rationalization and closed fishing season.
• Gear, area and temporal restrictions and mesh size regulation to prevent growth over fishing and recruitment over fishing.
• Fishery forecasts linked to biotic and abiotic features.
• Promoting tuna long lining, purse seining and oceanic squid jigging.
• Monitoring ecosystem health.
• Utilization of by catch by conversion into value added products.
• Development of infrastructure for production and post-harvest.
• Human resource development.
• Creation of environmental awareness.
• Organization of extension programes and inter institutional linkages.

1.1.3. Brackish water fisheries (Estuarine)

Meaning: Brackish water normally naturally occurs in estuaries, deltas of rivers, lagoons and backwaters, which everywhere in the world are under tidal regime. In such habitats the salinity of the water fluctuates widely between negligible to 35 ppt, depending on the phase of the tide and volume of fresh water discharged through the river into the sea. Estuaries and estuarine lakes have saline waters and only those fishes which can withstand changes in salty conditions thrive best. Some species of sardines and anchovies, Catfishes, perches, pearls pot or Etroplus are the most common.

Aquatic Resources: India possesses huge brackish water resources of over 1.2 million hectares suitable for farming. The extensive brackish waters include important estuaries (Hooghly - Matlah, Mahanadi and Godavari estuaries, Krishna, Cauvery on the east coast and the Narmada and the Tapti.), backwaters of Travancore-Cochin in Kerala are well known lagoons (Chilka Lake, Pulicat Lake) and backwaters (Vembanad) of Travancore-Cochin in Kerala and paddy fields (Pokkali -salt resistant deepwater fields along the Kerala coast). Chilka Lake in the state of Orissa is an open shallow brackish water lake having an area of 906 sq. km. in summer and 1165 sq. km. in rainy season. A long canal joins it with sea. Waters from river Daya (Mahanadi) and other smaller streams flow into it. Recent additions to the natural inland water bodies are man-made reservoirs, Bheries (manmade impoundments in coastal wetlands) of West Bengal. There are at present some 300 reservoirs both for capture as well as for culture fisheries.

In the estuary, lands are reclaimed by building walls or bunds to keep away floods and tidal waters. When the land is not under cultivation, it is used for rearing fishes. The bunds are filled with freshwater. This supply of water brings with it fish and their fry which grow up in these confined and protected shallows. When they reach a good size, they are caught for the market. Malabar is a famous for its embanked brackish water fisheries. Fishes and prawns in thousands are brought into these confined areas where they live and grow for about six months, when they are ready for capture.

Fisheries resources:

The finfish and shellfish that inhabit brackish waters are invariably euryhaline i.e. they form a group of organisms which physiologically withstands wide changes in salinity of the surrounding medium. Stenohaline organisms are devoid of physiological mechanisms to tolerate wide changes of salinity. So, a special type of fauna inhabits the estuarine habitat beyond the sea-end of which live the stenohaline and saltwater forms. Examples of euryhaline fish are a mullet (Mugil cephalus) and mud-skipper, Periophthalmus*and those of crustaceans are several species of penaeids (e.g. Penaeus monodon)* and crab (e.g. Scylla serrata*).

Shrimp is the single commodity that contributes almost the total production of the sector. Moreover, the black tiger prawn, Penaeus monodon, also contributes the lion’s share. The other shrimp species being cultivated are P. indicus, P. penicillatus, P. merguiensis, P. semisulcatus and Metapenaeus sp. Culture of crab species like Scylla serrata and S. tranquebarica has also been taken up by few entrepreneurs. There are several other finfish species like Mugil cephalus, Liza parsia, L. macrolepis, L. tade, Chanos chanos, Lates calcarifer, Etroplus suratensis and Epinephelus tauvina which possess great potential for farming, but commercial production of these species is yet to be taken up in the country. Further, Mullets and milkfish are important cultivable brackish water herbivorous fish, with high growth potential. Seed production technology of seabass, Lates calcarifer is available for commercialization.

Export/ Production: The brackish water production reported between 500 and 750 kg/ha/year with shrimp contributing 20 to 25 percent of the total Indian production. The production levels of shrimp recorded marked increase from 28,000 tonnes in 1988- 89 to 127,170 tonnes in 2001-2002.

*Source: Indian Fisheries and Aquaculture: Present Status and Future Prospects, S. Ayyappan, 2007.

Fig.1.5. State wise Fish Production.

Fig. 1.6. Fisheries capture (in tones) from various aquatic resources in India from 1950 to 2000.

Source: Capture of fisheries - Anonymous.

Review questions:

Long answer Questions:

1)      What is mean by marine fisheries? Explain the types of marine fisheries resources in India.

2)      Explain Fresh water fishery resources and types of fresh water resources.

Define /Explain

a)       Fisheries

b)      Pisciculture

c)       Induced Breeding.

d)      Coastal fish

e)       Mariculture

f)       Fish farming

Short answer questions.

        i.            What is Inland Fisheries?

      ii.            What is Marine Fisheries?

    iii.            What is Brackish water Fisheries?

     iv.            What is Riverine Fisheries?

       v.            What is Coastal Fisheries?

     vi.            Give two examples of marine fishes.

   vii.            Give two examples of freshwater fishes.

 viii.            Give two examples of pelagic fishes.

     ix.            Give two examples of demersal fishes.

       x.            Give two names of bio-geographical zones distinguished along the coast line of India.

Write Short Notes on the Following

        i.            Offshore and Deep sea fisheries

      ii.            Capture fisheries

    iii.            Culture fisheries

     iv.            Write a note on Induced Breeding technique.

       v.            What is Pisciculture? Describe in detail the Pond Culture.

     vi.            Write short notes on Estuarine Fisheries.

   vii.            Objectives of Fisheries.

 *******

1.2.      Different types of ponds used in fishery

(Contents - Nursery pond, Rearing pond, Stock pond)

Introduction:

The process of rearing and breeding of fishes in rivers, streams, ponds, irrigation canals and paddy fields is known as pisciculture. Pisciculture has an important place in Indian economy. It provides income and employment to millions of fishermen and farmers, particularly in the coastal areas.

Factors to be considered for pisciculture:

1. Topography or location of pond.

2. Water resources and quality of water.

3. Soil quality (Nutrients).

4. Temperature of the water.

Types of pisciculture

a.    Extensive pisciculture: growing fish on natural feed.

b.   Intensive pisciculture: Growing fish on artificial feed to maximize production.

c.    Monoculture: Growing a single type of fish in a given water body.

d.   Poly culture: Growing one or more types of fishes with different feeding habits together in a water body.

e.    Integrated pisciculture: Growing fish with agricultural crops or other animals.

The type of water body used to culture fishes varies.

a)   It could be a simple pond either a natural one or an artificial one.

b)   The fishes can be cultured in reservoirs that are constructed according to the specification.

c)   The fishes can be cultured in paddy fields that are filled with water.

d)   The fishes can be cultured in small areas near the estuaries. This is called brackish water culture. Here the salinity can be varied and controlled for cultivation of estuarine fishes.

e)   Marine fishes can be cultured in marine coastal waters. Fishes can also be cultured near the sea in the regions where they manufacture salts. The large saltpans are good for culture of fishes when they are not being used.

FISH CULTURE

The primary requirement for fish farming or culture is the availability of different types of ponds for rearing various stages of fish. The site of fish farming should have a steady supply of good quality water throughout the year. The topography should be such that the pond water can be self-drained. The use of ponds for pisciculture requires knowledge about pond ecology. The varieties of factors that affect the fish being cultured are area or size of the pond, its source of water, the physical and chemical properties of the water. The suitability of the pond for the various stages of the fish culture has to be considered.

Selection of pond

There is no hard and fast rule in fish culture for the shape and size of a fish pond however, for other various activities offish culture e.g. brood fish stocking, breeding, nursing and rearing purposes a definite shape and sized pond is preferred, Therefore, it is better to decide first for what purposes the pond is to be constructed? Generally, for fish production the fish pond is constructed in any shape and size as per available land, however, from operation and management aspect a rectangular or a square pond is most preferred. A small pond even is used for fish culture or fish production but smaller than 2 kanal ponds is not economical. The smaller pond than 2 kanal is usually used for only domestic purposes. A number of small ponds occupy considerable land area under the dikes and thus it deprives a considerable water area from fish production. On other side, the construction of a big pond is no doubt cost effective to construct a fishpond but it turns out difficult to manage the activity. Therefore, a good production pond ranges from 4-10 kanals. The production pond at no cost should be less than 2 kanals as it is not economical.

The main criteria to be kept in mind while selecting the pond is that the soil should be water retentive, adequate supply of water is assured and that the pond is not in a flood prone area. Derelict, semi derelict or swampy ponds can be renovated for fish culture by dewatering, desilting, repair of the embankments and provision of inlet and outlet.

Pond Management

Carp culture in ponds is basically a three-tier culture system where the first step begins with the rearing of spawn up to fry (2–3 cm) stage for 2–3 weeks in nursery ponds followed by rearing of 2–3 weeks old fry for about 3 months up to fingerling stage (8–12 cm) in rearing ponds before they are finally released in stocking ponds for growing up to table size fish. To ensure high rate of survival and growth during all the three stages of rearing, a package of management practices should be strictly followed, and slackness at any stage of the management procedure may affect farm productivity and profitability adversely.

Techniques of management involve (i) manipulation of pond ecology to ensure optimum production of natural fish food while maintaining the water quality parameters within tolerance limits of the stocked fish species; and (ii) the husbandry of fish through stock manipulation, supplementary feeding and health care. Broadly, the various steps involved in the management of ponds at all the three stages of culture may be classified as (i) pre-stocking, (ii) stocking and (iii) post-stocking management operations.

TYPES OF FISHING PONDS

Fish culture requires different types of ponds for the various stages of growth of fish. The types of ponds are as follows:

1. Breeding ponds

2. Hatchery ponds

3. Nursery pond

4. Rearing ponds

5. Stocking ponds

1. BREEDING PONDS: Sexually mature males and females are collected and left in these ponds for the breeding.

            First step in the fish culture is the breeding of fishes, therefore, for proper breeding special types of ponds are prepared called as breeding ponds. These ponds are prepared near the rivers or other natural water resources.

There are two types of breeding:

I. Natural Breeding or Bundh Breeding.

II. Induced Breeding.

I. NATURAL or BUNDH BREEDING -

            The natural bundhs are special types of ponds where natural riverine conditions or any natural water resource conditions are managed for the breeding of culturable fishes. These specially designed bundhs are constructed in large low-lying area having facility to accommodate large quantities of rain water. These bundhs are having an outlet for the exit of excess rain water. The shallow area of such bundhs is always used as spawning ground. These bundhs are of three types:

i.                 Wet bundh: The ponds specially constructed for fish breeding having water throughout the year are known as wet bundhs or perennial bundhs. The bundh can be of any size or shape, but the catchment area should be around 20-100 times of bundth.

Fig. 2.1.Wet Bundh

        An inlet is formed at the higher level of bundh for the entrance of the water while an    outlet is prepared in low lying area for the exit of the water from the bundh. The flow of water from outlet is controlled with the help of bamboo fencing or screen fencing in order to prevent escape of brood fish. In this type of bund there is autostocking of seed.

ii)    Dry bundh: This type of pond is purely seasonal with shallow water areas. This is        constructed by keeping soiled waters from three sides and open area from one side. In

Fig.2.2. Dry Bundh

       Monsoon period rain water flows towards this bundh and fills the pond.  But after monsoon water this bundh dries up after a month or two. The soil types of this bundhs are mainly laterite sandy or clayish.

iii)  Modern bundh: This is known as ‘Pucca bundh’. It is a masony construction and a sluice gate at the lower-most level of the bundh is the characteristic feature. The total exit of water from the bundh is possible by this gate so that after each spawning, bundh is cleared of water. According to the breeding nature of different fishes, suitable bundhs are used for spawning. The size of these bunds ranges from 0.2 to 2.5 m at full tank level.

Fig. 2.3. Schematic presentation of Natural and Induced breeding.

Collection Eggs or Fish Seeds:

The seeds are collected from the breeding ponds established near the Ganges, Yamuna, and Brahmaputra rivers. The Chilka Lake in Orissa is also a potential spot for seed collection. During monsoon months (June to August) when the rivers are over flooded, the fish migrate to adjoining shallow water lands. These submerged shallow areas act as breeding ground for the carps. The eggs are collected 12-24 hours after fertilization and made to hatch under protected conditions. For collection of eggs at the collection spot, two long bamboo poles are fixed near the bank of the river. A piece of round meshed mosquito net about 15’ x 6’ in dimension is fixed from these bamboo poles. At very 10-15 minutes this net is lifted up and the eggs so collected are removed to ‘hundi’. The eggs are then, transferred in hatching pits.

The collection of seeds is easy with a special net called the shooting net. This is a funnel like net made of closed mesh or coarse cloth. The narrow end of the funnel is a rectangular structure called as ‘gamcha’. This net is used to collect the seeds as well as small fingerlings.

2. HATCHERY PONDS: The seeds collected from breeding ponds are placed here in order to hatch the young fishes called fish fries.

Hatching is the mechanical and enzymatic process, of breaking of the egg shell (chorion) and release of larvae (hatching). Compared to hatching in stagnant waters, hatching in running water is retarded due to washing out of the hatching enzymes. Therefore, the technique of incubation in stagnant water is slightly preferable. Hatching may also be accelerated by increasing the water temperature up to about 30°C.

       Hatching Pits. The seeds collected are transferred to special hatching pits for hatching. This is done to keep the seeds safe from other predators. They are a series of pits located very close to the breeding ground. These pits are specially made in order to make the eggs hatch.

Hatching pits are of two types:

1.        Hatcheries: These are small sized ponds in which fertilized eggs are transferred. After

Fig.2.4. Hatching hapa

       2 to 15 hours the fertilized eggs are hatched. Some draw backs make the hatcheries                    unfit for advanced fish culture programme.

2.   Hatching hapas: Hapas are rectangular trough shaped tanks made up of cloth supported by bamboo poles fixed in the river. In these hapas fish eggs are aerated by continuous flow of current. The size of hapa is about 3’ x 1.5’ x 1’ and is made up of mosquito net cloth which is fixed into outer larger hapa made up of coarse cloth. Two types of hapas are designed; fixed type and floating type. The eggs are aerated by continuous flow of water.

Fig.2.5. Hatching hapa

Transportation of fries to nursery ponds - For local transportation large earthen wares hundies are used. Each hundi contains 50,000 to 70,000 fries of 4-5 mm. Water is constantly being aerated by agitation and for long distance it should be changed frequently. To keep the water inside the hundies clear and also to carry down the dead larvae 75-100 grams of fine clay is added to each hundi.

       For transportation of seedlings too far away distances earthenware hundies are not used because they are liable to break during loading and unloading in carries. In such cases metal containers are used. They are round vessels about 53 cms. in diameter and 38 cms. high. To maintain the normal oxygen content of water inside container different devices are in practice. One of which is a small semi rotator pump which sprays air over the entire surface of water.

       Another fact to be considered during transportation is to keep the temperature below 20⁰ C. A rise in temperature will increase the bacterial population which in turn will decrease the oxygen content. The carbon dioxide which comes out during respiration generally accumulates in the container resulting in the fall of pH. It has been found that the addition of 10% suspension of ant-hill earth keeps the pH constant.

Management of Fish seeds (Fry and Fingerling)

In fish life history, egg (fertilized) → Larva → fry→ fingerling → sub-adult/juvenile adult.

The young fishes are termed as spawn, fries and fingerlings which vary according to the food, age, type of the fishes.

1. The weight of hatchlings is about 1.0–1.5mg, and its total length is about 4mm. The newly hatched stages up to 8 – 10 mm in size are termed as spawn. The yolk sac contains high quality reserve food for growth and development during the larval stage. The larval stage ends when it fills up its air bladder with air, begins swimming in a fish-like manner and starts to eat external food that it becomes to fry.
2. The bigger stages up to 40mm are called fish fri. After 3–4 days when about ⅔ of the yolk sac is absorbed, the larva (weighing about 2–3 mg) becomes a feeding fry.
3. Fish fries after attaining a larger size more than 4cm (5 – 10 cm) are called fingerlings.

In addition to needing all the essential requirements of the larva e.g. adequate O2, suitable temperature, removal of waste matter etc, the fry also requires external food which should be adequate both qualitatively and quantitatively. The early fry may still have a part of the yolk left and can draw on it for sustenance from 1-4 days depending on the species. The fry spends this period and learns to find its own food. Fry are said to require a more precise and careful nursing to ensure their survival and proper growth. Fry are nursed in small earthen ponds which vary from 100-200m² for about 3-4 weeks to attain fingerling stage. Fingerlings are reared rather than nursed in bigger earthen ponds. Fingerling is the stage that is usually stocked. Management of these developmental stages is based on their fragility and difference in sizes in terms of their habitats, stocking density, feeding and control of their infections and diseases. These stages are crucial because there cannot be harvest without recruitment. Hence, these stages are called fish seed or recruits. The pond is usually prepared to have a standing crop of rotifers and must be checked to exclude cyclopoid copepods which are natural enemies of fry. Food is crucial for growth which must be observed daily. Fry have two sources of food during the initial stage – yolk and external food to ensure better survival.  It is part of the management that mixing of different age groups of same species should be avoided and it is advisable to use a monoculture of fish seed.

The most commonly provided artificial feed is finely ground and sieved through 100-150μm mesh called starter food. After two weeks, the size of feed particles is increased. Cutting the grasses on the dyke and throwing them around the shallow part of pond helps to increase natural food production in the pond. The artificial feeding continues but the size of food changes due to changes in the size of mouth. It is necessary to thin out the stock in order to provide sufficient space, O2, food to the fast growing fingerling.

Enemies of these stages must be managed too. These enemies change with the age of the fish.

These are categorized as (i) enemies of fry (ii) enemies of advanced fry and (iii) of fingerlings.

Identify these enemies and treat adequately. For example, enemies of fry include carnivorous

Cyclops, insect and insect larvae (e.g. dragonfly) predate largely on the fry. It has been stated that Cyclops are responsible for the highest mortality of fry at this stage.

   After about one month, the young fingerlings have to be removed from the small nursing pond and stock in a large pond.

3. (2.1.) NURSERY PONDS:  The nursery ponds are prepared much before breeding takes place. The nursery ponds are cleared of predatory fishes and weed fishes. The ponds are ready with sufficient growth of zooplankton and phytoplankton by using fertilizers such as cow dung with chemicals like ammonium sulphate, sodium nitrate and superphosphate. The growth of the planktons takes about 10 to 20 days. The pH of the water should be around neutral or slightly alkaline.

Purpose: The nursery ponds are smaller shallow reservoirs and are used mainly to nurse the hatchlings for a period of two to three weeks until they become fry (3 to 5 day old fish fries). The fri are fed well and retained for about 20 days. They are constructed near the spawning and the rearing ponds, and cover about 15sq.m in area.

Size: These ponds can be as large as half an acre. The ideal measurement suggested is 60’×40’×5’. The depth of the water column may be between 1.0 and 1.5 m.

Stocking density: The maximum stocking density of hatchlings is about 10 million/hec. These ponds are meant only for a short-time.

       Young fry about, 3 to 5 days old are transferred from spawning ponds to nurseries, where they remain for about 15-20 days. The main objective is to create suitable conditions of food availability and growth of fry, because at this stage they are very susceptible to hazards like the wave of action and predation.

Feeding is not necessary during the first week of nursing since the early fry does not accept artificial feed stuffs. Feeding on live zooplankton from nearby fresh water fish ponds is recommended in case of scarcity of food. Large quantities of zooplankton must be collected daily using 100–150 micron mesh plankton net.

However, after one week it is necessary to be fed with a finely ground and sieved (through 0.25 – 0.5mm mesh), artificial feed. This feed is composed of blood meal or fish meal (25%), brewer’s yeast (25%), oil cakes (heated soya /groundnut/cotton/sesame cake 25%) and wheat or rice bran (25%). Feeds are applied twice a day at a rate of 0.5 kg/are during 2nd week after stocking, 0.75 kg/are during the 3rd week and 1.0 kg/are during the 4th week. After one week of feeding, the size of the feed particles is increased to 0.5 – 1.0 mm but the composition remains the same.

The nursery ponds could be used two or three times in a single breeding season. The nurseries can also be used as production ponds.

           These ponds also called the transplantation ponds are the seasonal ponds.

The nursery ponds should be supplied with good water that is made to circulate. To establish a good standing crop of zooplankton, the nursery ponds are filled with non-polluted, slightly alkaline water (pH 6.5 to 8.0) and well exposed to sunlight. There should be no overcrowding of fries as this increases competition for space and food. There should be enough food supply. The ponds should be free of predatory insects and fishes.

Once the early fry have completed their metamorphosis they become advanced fry. The early fry stage ends when the fry fills up their supra-branchial air chamber with air. From this stage young fish (about 50 mg body weight) accept and grow well on artificial dry feeds.

The seedlings or fingerlings (weighing 2 – 5 g) during fifteen to 30 days in nursery pond, with the aid of artificial food attain a length of about 20-25 mm. After this period they are transferred to the rearing pond which is pre- prepared. The transference is done by netting the fries from nursery pond and transporting them into metal containers.

The heavy mortality fish fry has been recorded in nursery ponds. The following factors are responsible for such mortality:

a)       Sudden change in the quality of water from hatching hapa to nursery ponds.

b)      Lack of suitable food in pond.

c)       Presence of predatory fishes and predatory aquatic insects in the pond.

d)      Overgrowth of plankton.

e)       Decreased oxygen concentration in water.

f)       Cannibalism.

Precautions for nursery ponds:

              i.      In the nursery ponds water should be under good control and circulating.

            ii.      Pond should be nearer to the hatching ponds.

          iii.      Ponds should be predator free.

           iv.      To avoid overcrowding, fries should be kept in limited number.

            v.      Supply of food material should be proper.

   

2.     (2.2) REARING PONDS:

Purpose: These are used for rearing fry to fingerling stage (4 to 10 cm). These are deeper ponds in which fish fries from the nursery ponds are transferred and maintained here for about three months.

Size: Each rearing pond has size of 80’ x 20’ x 4’. These measures about 0.1 hectares. The ponds are deeper than the former types (generally 1.2 to 1.5 m) and have narrower sides to facilitate netting. In these ponds the advanced fry are raised for about 2 to 3 months. Such ponds are located near the spawning and nursery ponds and their number may vary depending upon one, two or three year rotation of carp culture.

The preparation of rearing pond is done in the same manner to that of nursery i.e. removal of weeds, elimination of predators, manuaring the pond etc. In rearing pond the fish reaches from fry to fingerling stage in about 2-3 months. By this time they attain a length of 75-125 mm. and are ready to be transferred to the stocking pond.

5. (2.3.) STOCKING PONDS:

Purpose: These are used to store fingerlings. Fingerlings grow to a table size fish in these ponds in the shortest possible time. These are larger ponds and the fingerlings are fed with artificial feed. Organic and inorganic fertilizers are used in increase growth.

       Size: The dimension of each stocking pond is 294’ x 100’x 8’. However, the size of stocking pond depends mainly on the geoecological condition of the area and the type of fish culture. Stocking ponds are large perennial ponds covering an area varying form 2-20 ha and average depth of about six feet.

Before releasing the fingerlings, the stocking pond is prepared to stock them. The process of preparing the pond is same as that of nursery and rearing ponds.

Feeding material: As for the proper organic manuaring is concerned cow dung is the best and should be used at the rate 20 to 25 thousands kg./hectare/year. The inorganic chemical fertilizers are also used viz.; super-phosphate, ammonium nitrate and ammonium sulphate at eh rate of 1,000 to1, 500 kg. / hectare /year.

The powdered rice, paddy, oil cakes, coconut, mustard, groundnut etc. are commonly used as artificial food for the fishes. The artificial food used for the fishes should be easily digestible in natural form and economically suitable. The best time for feeding the fishes is in the morning hours. The quality of food should not be changed suddenly. The amount of fertilizers used is totally dependent on the fertility of the soil, number of fishes and types of fishes being kept in the stocking ponds. Antibiotics are used to prevent infectious diseases. When the fishes attain the required size and weight they are harvested.

       In a period of one year, the young fishes grow to marketable size i.e. each fish can attain weight of about 1kg. They can be grown further for two or three years but their growth is slow.

For all types of ponds, the sides and bottom should be gently sloping towards the outlets, in order to facilitate complete draining as and when required.

Harvesting

Harvesting is done to capture the fishes from the water. The well grown fishes are taken out for marketing and smaller ones are again released into stocking ponds for their growth. In highly organized and well planned fish farming the fishes below a particular size are not generally captured. A pond can yield 3,000 to 10, 000 kgs / hectare/annum which is higher as compared to 800 kgs by old methods.

The fish culture technologies and economics are simple and understandable to the fish farmers. To produce one kilogram fish, the requirements are:-

• one cubic meter water
• one kilogram manure and 100 gm inorganic fertilizer
• one kilogram supplementary feed
• and one year time

II. INDUCED BREEDING

       The main source of the India’s fish seed supply comes from the riverine collection and certain percentage of it comes from the bundh type breeding places. In these collections it becomes quite difficult to sort out the fries of major carps, as large number of uneconomical fish fries and predatory forms also accompany the collection. Besides this the farmers have to wait for the arrival of monsoon and the time of breeding of different species of fishes also varies. to overcome these problems several persons successfully tried the process of induced breeding by injecting pituitary extracts and different hormones. Indian cat-fishes like Heteropneustes fossils and Clarias batrachus and carps like Labeo rohita, Labeo bata, Cirrhina mrigala and Cirrhina reba responded well to this method of breeding.

       The gonadotorpin hormone (F.S.H. and L.H.) secreted by pituitary gland influences the maturation of gonads and spawning in the fishes. In India, Khan (1938) successfully induced Cirrhinus mrigala to spawn by injecting mammalian pituitary hormone.

Method of hypophysation : First of all pituitary is taken out, then preserved in absolute alcohol inside the sealed tube in a desecrator at room temperature or in acetone for about 36 hours and stored in sealed phails in refrigerator. The pituitary glands should be taken out from fully matured, healthy and freshly killed fishes. The donor fish of the same species are most preferred for this purpose.

       For the preparation of extract, the weighed glands are homogenized in distilled water or 0.3% saline or glycerin and centrifuged for 15 minutes at 20,000 rpm. The supernatant thus obtained is injected intramuscularly on the back or on the base of the caudal fin. In some cases intraperitoneal injection is also recommended at the base of the pectoral fin.

       Usually the males and females used for these types of breeding are taken in proportion of 2:1. Female gets two injections at a lapse of six hours, the first dose being 2-3 mg. /kg. body weight and second being 5-8 mg/kg. body weight. The male gets only one injection of 2-3 mg. /kg. body weight along with the second injection of female. The injected fishes are kept in breeding hapas, made up of fine meshed mosquito net cloth and fixed in water by the help of bamboo poles. The fertilized eggs are collected and transferred to the hatching hapas as described above. It has been noticed that well fed and healthy fishes respond more quickly and successfully than ill fed and unhealthy fishes. It is advisable to feed the fishes chosen for this purpose with oil cake and rice bran for 2-3 months prior to the treatment and this will give a better result.

Practice of Induced breeding Fishery in Haryana State:

Fish Seed Production

Quality fish seed is the pre-requisite for successful fish farming. Department is using the techniques of hypophysation for the production of fish seed of culturable varieties. The breeding season of common carp fish in Haryana is February-March every year where as the breeding season of other species is monsoon season. Brood stock of required fish is maintained and sex-wise segregate is made two month before. The pairing is made and injected with calculated dose of pituitary gland or ovaprim, ovatide or ovpal is injected to male and female fish. Within the 6-8 hours of the injection eggs from female and sperm from male are released in the water. The fertilization is external. Normally one kg fish releases about one lakh eggs. The hatchlings are known as spawn. The spawn is reared in the nursery pond. After 15 days, the spawn attains the size of 25 mm and ready for stocking in the pond. More than 50 lakh fry can be produced per hectare fish seed farm in both the seasons in a year. The income from sale of fish seed is Rs. 3.25 lakh approx. per year @ Rs. 6500 per lakh. Fisheries department provides technical and financial assistance for setting up of ecotype hatchery and fish seed rearing units.

Review questions:

I. Choose the correct answer:

1. Large ponds in which the fingerlings are fed with artificial feed

a. Breeding ponds b. Nursery ponds c. Hatchery ponds d. Stocking ponds

2. Hapas are used for which of the following stage

a. Eggs b. larva c. Fingerlings d. adult fish

3. In which of the following ponds 3 to 5 day old fish fries are fed and stored for 20 days.

a. Breeding ponds b. Nursery ponds c. Hatchery ponds d. Stocking ponds

II. Define / Explain:

1. Pisciculture b. Hatching hapa c. Fingerlings d. Nursery ponds e. Artificial food for Fish

III. Distinguish between:

1. Breeding pond and Stocking pond
2. Nursery pond and Rearing  pond
3. Fingerlings and Adult Fish

IV. Write short note on

1. Nursery pond

2. Rearing ponds

3. Stocking ponds

IV. Long answer questions:

1. What is Pond culture? Describe in brief different types of ponds used in fishery.
2. What is Pisciculture? Describe in brief different types of ponds used in fishery.
3. Give any two types of ponds used in fishery.

1.3. Habit, habitat and culture methods of freshwater forms                  

a)                                     Rohu (Labeo rohita)

b)                                     Catla (Catla catla)

c)    Mrigal (Cirrhinus mrigala)

d)    Giant prawn (Macrobrachium rosenbergi)

In India, carps from the family Cyprinidae are selected for culture because they possess all the required qualities. They have following characteristics.

I. Carps are herbivorous and omnivorous, they feed on plankton (phytoplankton and zooplankton), decaying weeds and debris and other aquatic plants in the pond.

2. They are resistant to temperature, turbid water and diseases.

3. They can tolerate low oxygen content.

4. The) have a fast growth rate and can breed in ponds with special treatment like induced breeding.

5. They have good taste to their flesh and good demand in the market.

6. They never compete to each other for food and space.

Following are the important fishes selected for fish culture in India.

(A) Indian Major Carps

a. Catla catla.

b. Labeo rohita.

c. Cirrhina mrigala.

d. Labeo calbasu.

e. Labeo fimbriatus.

f. Labeo bata.

(B) Exotic Carps

a. Cprinus carpio (common carp or scale carp)
b. Ctenopharyngodon idella (Grass carp)
c. Hpopthalmichthys molitrix (Silver carp)

d. Osphronemus gourami (Gourami)
e. Tilapia mossambica (Tilapia)

Here three common major carps are included for study purpose, these are described with respective their habits, habitat and culturing methods

11.3.a. Rohu - Labeo rohita  Hamilton, 1822 [Cyprinidae]

It is the quick growing carp, known as Rohu or Rui in Bengal. Bihar, Assam. Uttar Pradesh and Punjab, Rohi in Orissa: Bonha gandumeenu in Andhra Pradesh. It is found in Pakistan, Bangladesh and Burma. Labeo rohita is the fish of northem Indian rivers. It was later on transplanted into southern Indian rivers but has not yet established itself in any of the southern rivers,

Distinguishing Characters:

                       i.   Head is small and somewhat pointed;

                     ii.   Mouth is terminal with fringed lower lip;

                   iii.   Sides are dull reddish in colour, whereas, fins are pink reddish in colour;

                   iv.   Body is more linear than that of Catla;

                     v.   Maxillary barbel is present, sometime rostral barbel is also present.

                   vi.   Eyes dorsolateral in position, not visible from outside of head;

                 vii.   branched dorsal fin rays 12 to 14

               viii.   caudal fin deeply forked;

                   ix.   pre-dorsal scale 12-16; lateral line scales 40 to 44;

                     x.   lateral transverse scale-rows six or six and a half between lateral line and pelvic fin base;

Fig. 3.1 Labeo rohita side view

Food and Feeding Habits:

Rohu is a column bottom feeder fish. Its interior fringed-lipped mouth is adopted for browsing habits. Hatchlings feed on Zoo-plankton including rotifers, cladocera and copepod. Hatchlings later on feed on phytoplankton, periphyton and vegetable debris. Fingerlings feed on vegetable debris and microscopic plants. Labeo adult’s feed on-vegetable debris; microscopic plants; decayed higher plants, detritus and mud.

Growth:

It is also fast growing fish. It grows relatively a little slower than the Catla. It grows up to 900 gm in one year; 2-3 kg in 2nd year and 4-5 kg by the end of 3rd year.

Maturity, Fecundity and Breeding:

Rohu attains maturity by the end of 2nd year of its life. Average size and weight at maturity is 29-30 cm. and 282gm. Fecundity ranges from 2, 25,600-2.79, 400 eggs. It breeds in river and Bundh, during monsoon.

Eggs and Hatchlings:

Eggs are slightly reddish, transparent, non- adhesive and demersal. Eggs are about 1.5 mm in diameter. Hatching takes place in 16-18 hours at optimum temperature of 27°C. Hatchlings are 3.8 mm in length. Narrow portion of the yolk of hatchlings is equal to the bulbous part.

The nibbling type of mouth with soft fringed lips, sharp cutting edges and absence of teeth in the bucco-pharyngeal region helps the fish to feed on soft aquatic vegetation which do not require seizure and crushing. The modified thin and hair-like gill rakers also suggest that the fish feed on minute plankton through sieving water. In ponds, the fry and fingerlings exhibit schooling behaviour mainly for feeding; however, this habit is not observed in adults.

Rohu is a eurythermal species and does not thrive at temperatures below 14 °C. It is a fast growing species and attains about 35-45 cm total length and 700-800 g in one year under normal culture conditions. Generally, in polyculture, its growth rate is higher than that of mrigal but lower than catla.

Culture Method:

Selection of pond

       The main criteria to be kept in mind while selecting the pond is that the soil should be water retentive, adequate supply of water is assured and that the pond is not in a flood prone area. Derelict, semi derelict or swampy ponds can be renovated for fish culture by dewatering, desilting, repair of the embankments and provision of inlet and outlet.

Pond Management

     Carp culture in ponds is basically a three-tier culture system where the first step begins with the rearing of spawn up to fry (2–3 cm) stage for 2–3 weeks in nursery ponds followed by rearing of 2–3 weeks old fry for about 3 months up to fingerling stage (8–12 cm) in rearing ponds before they are finally released in stocking ponds for growing up to table size fish. To ensure high rate of survival and growth during all the three stages of rearing, a package of management practices should be strictly followed, and slackness at any stage of the management procedure may affect farm productivity and profitability adversely.

      Techniques of management involve (i) manipulation of pond ecology to ensure optimum production of natural fish food while maintaining the water quality parameters within tolerance limits of the stocked fish species; and (ii) the husbandry of fish through stock manipulation, supplementary feeding and health care. Broadly, the various steps involved in the management of ponds at all the three stages of culture may be classified as (i) pre-stocking, (ii) stocking and (iii) post-stocking management operations.

Fig.3.3.Production cycle of Labeo rohita

Rohu is the principal species reared in carp polyculture systems along with the other two Indian major carps viz., catla, Catla catla and mrigal, Cirrhinus mrigala. Due to its wider feeding niche, which extends from column to bottom, rohu is usually stocked at relatively higher levels than the other two species. In India, the species is also cultured within composite carp culture systems incorporating all three Indian major carps, as well as common carp (Cyprinus carpio) and two Chinese carps viz., silver carp (Hypophthalmichthys molitrix) and grass carp (Ctenopharyngodon idellus). However, the percentage of rohu, even within this six-species combination, is retained at 35-40 percent, similar to that in the three-species polyculture system. The higher consumer preference and market demand for rohu during recent years have also led to the practice of two-species culture with catla. The latter type of aquaculture is occurring in over 100 000 ha of ponds in the Koleru lake region of Andhra Pradesh, India, in which rohu forms more than 70 percent of the stock.

Induced breeding: In nature, spawning occurs in the shallow and marginal areas of flooded rivers. The spawning season of rohu generally coincides with the south-west monsoon, extending from April to September. In captivity with proper feeding the species attains maturity towards the end of second year. However, breeding does not take place in such lentic pond environments; thus induced breeding becomes necessary.

The pituitary extract is used, females are injected with a stimulating dose of 2-3 mg/kg BW followed by a second dose of 5 to 8 mg/kg after a lapse of six hours; males are given a single dose of 2-3 mg/kg at the time of second injection of the female. When synthetic commercial formulations (purified salmon gonadotropin and dopamine antagonists such as Ovaprim, Ovatide and Wova-FH) are used, a single dose of 0.4-0.5 ml/kg body weight (females) or 0.2-0.3 ml/kg (males) is administered. Besides artificial breeding the eggs/seeds are also collected from riverine sources in certain small areas.

Seed Production:

The Chinese circular hatchery is the most common system used for seed production. This type of hatchery possesses three principal components, viz., spawning/breeding tank, incubation/hatching tank, and water storage and supply system.

1. Spawning or Breeding tank: The depth of water in the breeding tank is maintained at up to 1.5 m, based on the brood stock density; 3-5 kg brood stock/m³ is usually recommended. The female: male ratio is normally maintained at 1:1 by weight (1:2 by number).
2. Hatching tank or Incubation tank: The size and number of hatching tanks vary, based on the production requirements and size of the breeding tank. The optimum egg density for incubation is 0.7-0.8 million/m³. In general, 0.15-0.2 million eggs/kg of female are obtained.

The seed rearing normally involves a two-tier system, i.e. a 15-20 days nursery phase for raising fry, followed by a two-three months phase for fingerling production.

3. Water storage and supply system: It comprises of three ponds having inlet and outlet of water to the tanks to fill water, for cleaning process and for harvesting purpose. The three ponds are: Nursery pond, Rearing pond, and Stocking pond.

Rearing fingerlings: 

a)       Nursery Ponds - Nursery phase

Three day old hatchlings, measuring about 6 mm, are reared up to fry of 20-25 mm in small earthen nursery ponds of 0.02-0.1 ha. In certain areas, brick-lined or cement tanks are also used as nurseries. In many cases, although the stocking of a single species is normally advocated, farmers resort to stocking all three species of the Indian major carps. Pre-stocking nursery pond preparation should include the removal of aquatic weeds and predatory fish, followed by liming and fertilization with organic manures and inorganic fertilizers. Aquatic insects are eradicated by the application of a soap-oil emulsion or removed by repeated netting before stocking. In earthen ponds, hatchlings are normally stocked at 3-10 million/ha, but higher levels of 10-20 million/ha are used in cement nurseries. The hatchlings normally receive a supplementary feed of a 1:1 w/w mixture of rice bran and groundnut/mustard oil cake. Survival ranges from 30 to 50 percent. Though the beneficial effects of pre-stocking nursery pond preparation are well-established, some of these activities are often ignored by the farmers, resulting in poor fry survival. The non-availability of commercial feed, forcing the farmers to resort to the conventional bran-oilcake mixture, is another limiting factor for the growth and survival of fry.

Fingerling production:

b)      Rearing Ponds

The nursery-raised fry of 20-25 mm are further reared for two-three months to 80-100 mm (6-10 g) fingerlings in earthen ponds of 0.05-0.2 ha. Here, rohu are grown together with other carp species at combined densities of 0.2-0.3 million fry/ha, with the rohu constituting about 30-40 percent of the total. Pond fertilization with both organic and inorganic fertilizers and supplementary feeding with the conventional mixture of rice bran and oil cake are the norm; however, the dosage and form of application vary with the farming intensity and inherent pond productivity. The overall survival in these fingerling rearing systems ranges from 60 to 70 percent.

Fig.3.4 Larval Developmental stages of Labeo rohita

On growing techniques: 

c)       Stocking pond

Grow out production of rohu, confined mainly to earthen ponds. The fingerlings of size more than 100 to 125 mm are transferred to stocking pond till they attain marketable size i.e. >300g.The practical technology includes predatory and weed fish control; stocking of fingerlings at a combined density of 4 000-10 000/ha (30-40 percent rohu); pond fertilization with organic manures like cattle dung or poultry droppings and inorganic fertilizers; the provision of a mixture of rice bran/wheat bran and groundnut/mustard oil cake as supplementary feed, fish health monitoring and water management. The grow-out period is normally one year, during which rohu grows to about 700-800 g. In certain cases the farmers resort to partial harvesting of marketable size groups (>300 g) at intermittent intervals. In the Koleru lake area of Andhra Pradesh, the centre of commercial carp farming activity in India, the practice commonly involves the rearing of rohu and catla in two-species farming, with rohu constituting over 70 percent of the stock. In this case, stunted juveniles (i.e. fingerlings reared in crowded conditions for over one year, and 150-300 g in size) are used as the stocking material. The usual harvestable size of rohu is 1-1.5 kg and is achieved within a culture period of 12-18 months. Production levels of 6-8 tonnes/ha is recorded in such cases, with rohu contributing about 70-80 percent of the biomass.

When fingerlings are stored at higher stocking densities they are parasitized by an ectoparasite, carp lice (Argulus spp.), it is the major problem for rohu compared to other carps, causing reduction in growth and sometimes mortalities.

Rohu also forms one of the important components in the sewage-fed carp culture system practiced in an area totaling over 4 000 ha in West Bengal, India. In this form of culture, which includes multiple stocking and the multiple harvesting of fish larger than 300 g, primary treated sewage is provided to the fish ponds as the main input. Even without the provision of supplementary feed, this system produces 2-3 tonnes/ha/yr; with supplementary feeding, this can be increased to 4-5 tonnes/ha/yr.

Harvesting techniques 

As carp are cultured in ponds and tanks that are usually quite small, manually operated dragnets are the most convenient gear used for harvesting. The length of these nets depends on the width of the pond. In most cases fish are harvested at the end of the culture period through repeated netting. However, in some cases, this is followed by total draining of the ponds. Cast nets are often used for partial harvesting in small and backyard ponds. In water bodies where multiple stocking and multiple harvesting are practiced, the harvesting of larger sizes (300-500 g) is usually initiated after six-seven months of culture, and the smaller ones are returned to the pond for further growth. Multiple stocking and multiple harvesting is the most common practice in sewage-fed carp culture system.

Handling and processing 

Rohu is the most preferred species among the cultivated Indian major carps. The marketing of this species mostly relies on local markets, where it is sold fresh. In large commercial farms where the harvest is considerable, fish, after washing thoroughly in water, are packed with crushed ice at 1:1 ratio in rectangular plastic crates (usually 60 cm x 40 cm x 23 cm in size). Long-distance transport of these ice-packed fish in insulated vans is a common practice in countries like India, where rohu are even transported over 3 000 km by road. Post-harvest processing and value-addition of this species is almost non-existent at present in any of the producing countries.

1.3.b.Catla - Catla catla  Hamilton, 1822 [Cyprinidae]

Catla catla is the fastest growing carp and is commonly called as Catla in Assam, Bengal, Maharashtra, Bihar and Uttar Pradesh, Bhakur in Orissa, Thila in Punjab, Bocha in Andhra Pradesh and Thappamoen in Chennai. Catla is found in Northern rivers of India and Krishna and Cauvery. It is also found in the rivers of Pakistan, Bangladesh, Burma and Thailand. It has been transported in Shrilanka and Israel. The fish is distributed throughout India.

Distinguishing Characters

              i.      Body is deep with a conspicuous head;

            ii.      Mouth is large and upturned;

          iii.      Upper lip absent, lower lip very thick and non-fringed;

           iv.      Pharyngeal teeth in three row, 5.3.2/2.3.5 pattern;

             v.      Barbels are absent;

           vi.      Single broad dorsal fin with 14 to 16 branched rays;

         vii.      Body is ordinarily dull. silver white in colour.

       viii.      It attains maximum length of about 180 cm. but is suitable for food when it is not more than 61 cm.

9. Eyes large and visible from underside of the head;
10. Gill rakers long and fine; dorsal fin inserted slightly in advance of pelvic fins, with 14 to 16 branched rays, pectoral fins long extending to pelvic fins; caudal fin forked;
11. Lateral line with 40 to 43 scales.

Fig. 3.5 Catla catla side view

 Food and Feeding Habit:

It is surface-column feeder fish. Exclusively feeds on plankton. It has upturned mouth and the large gill rackers which are adapted to feeding on the floating organisms like plankton. Catla spawn and early fry feed on rotifers (Brachionous), cladocera (Monia and Daphnia), copepoda (Naupleus; Cyclops), diatoms; phytoplankton consists of Phacus; Cydorina; Spirogyra and Microcystes. Some detritus is also taken as food. This stage is called as non-zoophyto-planktophagus stage. Catla fry and fingerlings feed on cladocera; copepod and phytoplankton. Catla adult feeds on copepod, cladocera, rotifers and Naupleus. It takes phyto-plankton as occasional food and vegetables and detritus as an emergency food.

Growth:

            Catla is the fastest growing fish among the Indian major carps. Growth of catla varies according to ecological factors and stocking rates. In first years, it grows up to 900 gm by weight, in the second year it grows up to 4.5 kg by weight and 6.7 kg by weight in the third year.

Maturity, Fecundity and breeding:

It attains maturity by the end of the 2nd year of its life.  Generally male matures earlier then the female. Average size and weight of Catla at maturity is 40-50 cm length and 1 .5 kg weight. Depending on length and weight of the ovary the fecundity of mature female ranges from 230831 to 420225 eggs.   It breeds in rivers during the rainy months from June to August. It does not breed in ordinary pond water, but can breed in special types of ponds like Bundh. In Assam, Bengal and Bihar early fry are collected in the months of June - July; whereas in Orissa Punjab and Andhra Pradesh, fry are collected during the months of July and August.

Eggs and Hatchlings:

Eggs are of light red to light violet in colour, spherical in shape, 2.0-2.2 mm in diameter. Eggs are demersal, transparent and nonadhesive. They swell after fertilization and grow to 4.4-5.5 mm. Hatching takes place from 16-18 hours after fertilization. Optimum temperature required is 27°C-29°C. Hatchlings are 7 mm in length.

Among the three Indian major carps, catla is the most difficult to breed as it requires precise environmental conditions for spawning. Under normal conditions catla grows to 1-1.2 kg in the first year, compared to 700-800 g and 600-700 g for rohu and mrigal, respectively.

Culture Method:

Selection of pond

The main criteria to be kept in mind while selecting the pond is that the soil should be water retentive, adequate supply of water is assured and that the pond is not in a flood prone area. Derelict, semi derelict or swampy ponds can be renovated for fish culture by dewatering, desilting, repair of the embankments and provision of inlet and outlet.

Pond Management

Carp culture in ponds is basically a three-tier culture system where the first step begins with the rearing of spawn up to fry (2–3 cm) stage for 2–3 weeks in nursery ponds followed by rearing of 2–3 weeks old fry for about 3 months up to fingerling stage (8–12 cm) in rearing ponds before they are finally released in stocking ponds for growing up to table size fish. To ensure high rate of survival and growth during all the three stages of rearing, a package of management practices should be strictly followed, and slackness at any stage of the management procedure may affect farm productivity and profitability adversely.

Techniques of management involve (i) manipulation of pond ecology to ensure optimum production of natural fish food while maintaining the water quality parameters within tolerance limits of the stocked fish species; and (ii) the husbandry of fish through stock manipulation, supplementary feeding and health care. Broadly, the various steps involved in the management of ponds at all the three stages of culture may be classified as (i) pre-stocking, (ii) stocking and (iii) post-stocking management operations.

Fig.3.6.Larval Developmental stages of Catla catla

Figure of Production cycle of Catla catla is same to that of Labeo rohita

             Catla, the second most important species after rohu (mrigal is third), is used as the surface feeder component in Indian major carp polyculture systems. In the six-species composite system with rohu, mrigal, common carp, grass carp and silver carp, catla shares the upper feeding niche of the pond with silver carp. In the three-species system in India the proportion of catla stocked is usually kept at 30-35 percent, while in six-species culture it forms 15-20 percent. In a two-species commercial carp production system practiced in the Koleru lake region of Andhra Pradesh, the major carp producing region in India, stocked catla constitute 20-30 percent of the total, the rest being rohu.

Induced breeding:

Induced breeding of catla has been catering for almost the entire seed requirement in all the countries where it is cultured, although riverine collection still forms the seed source in certain small areas. Hormonal stimulation for induced breeding often gives poor result in catla, compared to other major Indian carps. The pituitary extract is used, females are injected with a stimulating dose of 2-3 mg/kg BW followed by a second dose of 5 to 8 mg/kg after a lapse of 6 hours; males are given a single dose of 2-3 mg/kg at the time of second injection of the female. When synthetic commercial formulations (purified salmon gonadotropin and dopamine antagonists such as Ovaprim, Ovatide and Wova-FH) are used, a single dose of 0.4-0.5 ml/kg BW (females) or 0.2-0.3 ml/kg (males) is administered.

Seed Production:

The Chinese circular hatchery system is used for large-scale seed production.

1. Spawning or Breeding tank: Brood stock, stocked at 3-5 kg/m3 and in a female: male ratio of 1:1 by weight (1:2 by number) are injected with suitable inducing agents and released into a breeding tank with a water depth of about 1.5 m.
2. Hatching tank or Incubation tank: The fertilized eggs, collected 8-12 hours later, are transferred to the hatching tank and kept for 64-72 hours for further incubation and hatching. The number and size of the hatching tanks in this type of hatchery varies, based on the production requirements and size of the breeding tank. In general, spawn recovery varies from 0.1-0.12 million eggs/kg of female brood stock.
3. Water storage and supply system: It comprises of three ponds having inlet and outlet of water to the tanks to fill water, for cleaning process and for harvesting purpose. The three ponds are: Nursery pond, Rearing pond, and Stocking pond.

Rearing fingerlings: 

a)       Nursery Ponds - Nursery phase

The seed rearing normally involves a two-tier system, i.e. a 15-20 days nursery phase for raising fry, followed by a 2-3 months phase for fingerling production.

Three-day old larvae, measuring about 6 mm, are reared for 15-20 days in small earthen nursery ponds of 0.02-0.1 ha, during which they reach 20-25 mm. In certain areas, brick-lined or cement tanks are also used as nurseries. Where only catla are stocked, earthen nurseries are stocked at 3-10 million/ha and cement nurseries at 10-20 million/ha. In many cases, however, farmers stock multiple carp species due to the non-availability of sufficient ponds for separate stocking. Pre-stocking nursery pond preparation includes the removal of aquatic weeds and predatory fishes, followed by liming and fertilization with organic manures and inorganic fertilizers. The application of soap-oil emulsion, or repeated netting with a suitable mesh size, is used to eradicate aquatic insects before stocking. A powdered mixture of rice bran and oilcake is the common supplementary feed. Survival rates normally range from 30 to 40 percent; however, survival often remains low due to improper management. The survival level of catla in nursery ponds is normally lower than that for rohu and mrigal.

Fingerling Rearing /production:

b)      Rearing Ponds

The nursery-raised fry of 20-25 mm are further reared for 2-3 months to 80-100 mm (6-10 g) fingerlings in earthen ponds of 0.05-0.2 ha. Catla fry are reared along with rohu and mrigala in equal proportions at combined densities of 0.2-0.3 million fry/ha. Pond fertilization with both organic and inorganic fertilizers and supplementary feeding with the conventional mixture of rice bran and oil cake are the norm; however, the dosage and form of application vary with the farming intensity and inherent pond productivity. The overall survival in these fingerling rearing systems ranges from 60 to 70 percent.

On growing techniques: 

c)       Stocking pond

Being a surface feeder that is highly preferred by consumer, catla forms an integral component in carp polyculture systems. It is the fastest growing species among the three Indian major carps. Standardized practice for grow-out in the carp polyculture system includes control of predatory and weed fish through the application of chemicals or plant derivatives; the stocking of fingerlings at a combined density of 4 000-10 000 fingerlings/ha; pond fertilization with organic manures such as cattle dung or poultry droppings and inorganic fertilizers; supplementary feeding with a mixture of rice/wheat bran and oil cake; and fish health monitoring and water management. The normal grow-out period is one year, during which it grows to about 1.0 kg. In the Koleru lake area of Andhra Pradesh, the centre of commercial carp farming activity in India with a production water area of over 100 000 ha, the grow-out period extends up to 18 months. In this area, stunted juveniles (i.e. fingerlings reared in crowded conditions for over one year, and 150-300 g in size) are used as the stocking material and the average size of catla harvested is 1.5-2.0 kg. The production levels recorded in carp polyculture systems usually remain at 3-5 tonnes/ha/yr, with catla contributing about 20-30 percent of the biomass.

            Catla also forms one of the important components in the sewage-fed carp culture system practiced in an area totaling over 4 000 ha in West Bengal, India. In this form of culture, which includes multiple stocking and multiple harvesting of 300 g fish, primary treated sewage is provided to the fish ponds as the main input. Even without the provision of supplementary feed, this system produces 2-3 tonnes/ha/yr; with supplementary feeding, this can be increased to 4-5 tonnes/ha/yr.

Harvesting techniques 

Consumers generally prefer catla to be large 1-2 kg. Thus, farmers often resort to harvesting this species only at the end of the culture period instead of during intermittent harvesting. In water bodies where multiple stocking and multiple harvesting are practiced, the harvesting of larger sized fish (over 500 g) is usually initiated after 6-7 months of culture, while the smaller ones are returned to the pond for further growth. Manually operated dragnets are the most commonly used gear for harvesting carps. Marketable sized fish are usually harvested through repeated netting. Cast nets are another important gear frequently used for partial harvesting of fish in small and backyard ponds.

Handling and processing 

Catla are marketed mostly in local markets, where they are sold fresh. The marketing of this species mostly relies on domestic markets, where it is sold fresh. In large commercial farms where the harvest is considerable, fish, after washing thoroughly in water, are packed with crushed ice at 1:1 ratio in rectangular plastic crates (usually 60 cm x 40 cm x 23 cm in size). Long-distance transport of these ice-packed fish in insulated vans is a common practice in countries like India, where catla are even transported over 3000 km by road to fish-deficit regions.

1.3. c. Mrigal - Cirrhinus mrigala Hamilton, 1822 [Cyprinidae]

         Cirrhina mrigala is commonly called as More in Punjab; Naini in Uttar Pradesh and Bihar; Mrigal in Bengal and Assam, Mirikali in Orissa and Yerrameen in Andhra Pradesh, The fish originally found in northern Indian rivers but also established in southern rivers of India. It is also found in Pakistan, Bangladesh & Burma.

Distinguishing Characters:

                 i.             Body is relatively linear; Body bilaterally symmetrical and streamlined, its depth about equal to length of head; body with cycloid scales,

               ii.             Small head with blunt snout and terminal mouth; head without scales;

             iii.             Lips are thin and non-fringed;

              iv.             Body is bright silvery in colour with reddish fins;

                v.             The dorsal fin has 12 to 13 branched rays;

              vi.             Single pair of short rostral barbels;

            vii.             Pharyngeal teeth in three rows, 5.4.2/2.4.5 pattern;

          viii.             Pectoral fins shorter than head;

              ix.             Lateral line with 40-45 scales; lateral transverse scale rows 6-7/5½-6 between lateral line and pelvic fin base.

Fig. 3.7 Cirrhina mrigala side view

Food and Feeding Habits:

It is a bottom feeder and omnivorous. The terminal lips are adopted for picking up things from the bottom (mud). Hatchlings feed on Rotifers (Brachionus), Cladocera (Monia, Daphnia), Copepod (Nauplius, Cyclops, and Diptomus,) Phytoplankton (Phacus, Eudorina, Spirogyra and Microcystes).

Adults feed on phytoplankton detritus, debris, sand and mud. The proportion of animal matter is very poor in food. In emergency, it takes higher plant matter.

Growth:
              It grows slower than Catla and Rohu. It can grow up to 1.8 kg, 2.6 kg & 4 kg weight by the end of 1st, 2nd & 3rd year; where as in length it grows up to 58 cm 72 cm, & 78 cm in 1st 2nd and 3rd year.

Maturity, Fecundity and Breeding: It matures sexually only when it is about two years old. Fecundity of mrigal is about 1.44-1.52 lakhs eggs per 1 kg of body weight. It breeds in the river and bundh during south west monsoon period.

Eggs & Hatchlings: Eggs are round in shape, brownish in colour, non adhesive and demersal. Diameter of the eggs is about 5.5 mm. Hatchlings are about 5.20 mm in length. Narrow portion of the yolk is greater in length than the bulbous part. Yolk is more or less club shaped.

           Hatchlings of mrigal normally remain in the surface or sub-surface waters, while fry and fingerling tend to move to deeper water. Adults are bottom dwellers. Mrigal is eurythermal, appearing to tolerate a minimum temperature of 14 ºC. In culture, the species normally attains 600-700 g in the first year, depending on stocking density and management practices. Among the three Indian major carps, mrigal normally grows more slowly than catla and rohu. The rearing period is usually confined to a maximum of two years, as growth rate reduces thereafter. However, mrigal is reported to survive as long as 12 years in natural waters. As mrigal needs a fluviatile environment for breeding it does not breed in ponds. However, captive breeding in hatcheries has been made possible through induced breeding by hypophysation and the use of synthetic hormones. Mrigal usually breeds at 24-31 ºC.

Culture Method:

Fig.3.8. Larval developmental stages of Mrigal

Figure of Production cycle of Cirrhinus mrigala is same like that of Labeo rohita.

             Mrigal is cultured mainly as a component of carp polyculture systems in the ponds of India and Bangladesh, the major producing countries. Mrigal is normally cultured along with the other two Indian major carps - catla (Catla catla) and rohu (Labeo rohita). It is also cultured in composite carp culture systems that include the three Indian major carps as well as two Chinese carps - silver carp (Hypophthalmichthys molitrix) and grass carp (Ctenopharyngodon idella) - and common carp (Cyprinus carpio). Being a bottom feeder, mrigal is usually stocked at 20-30 percent of the total species stocked in three-species culture, while in six-species culture mrigal constitutes only about 15-20 percent. In India, carp is cultured in about 900 000-1 000 000 ha of ponds and 'tanks' (water bodies that are usually larger than a pond but less than 10 ha) that are privately or community owned.

Selection of pond

           The main criteria to be kept in mind while selecting the pond is that the soil should be water retentive, adequate supply of water is assured and that the pond is not in a flood prone area. Derelict, semi derelict or swampy ponds can be renovated for fish culture by dewatering, desilting, repair of the embankments and provision of inlet and outlet.

Carp culture in ponds is basically a three-tier culture system where the first step begins with the rearing of spawn up to fry (2–3 cm) stage for 2–3 weeks in nursery ponds followed by rearing of 2–3 weeks old fry for about 3 months up to fingerling stage (8–12 cm) in rearing ponds before they are finally released in stocking ponds for growing up to table size fish.

Induced breeding:

Mass scale seed production of mrigal in hatcheries through induced breeding now supplies almost the entire seed requirement in all the producing countries. The riverine collection still forms the source of seed in certain small areas. As mrigal does not breed in confined waters, injections of pituitary extract is used, females are injected with a stimulating dose of 2-3 mg/kg BW followed by a second dose of 5 to 8 mg/kg after a lapse of 6 hours; males are given a single dose of 2-3 mg/kg at the time of second injection of the female. The synthetic commercial formulations (purified salmon gonadotropin and dopamine antagonists such as Ovaprim, Ovatide and Wova-FH) are used; a single dose of 0.4-0.5 ml/kg BW (females) or 0.2-0.3 ml/kg (males) is administered.

Seed Production:

1. Spawning or Breeding tank: The spawn recovery of mrigal usually ranges from 100 000 to 150 000/kg. The Chinese circular hatchery is the most common system used. In this system, brood stocks are kept at 3-5 kg /m3, with a 1:1 female: male stocking ratio by weight (1:2 by number).
2. Hatching tank or Incubation tank: Fertilized eggs are obtained after 6-8 hours and are transferred to the hatching tank, optimally stocked at 700 000-800 000/m3. Water circulation is continuous and the eggs are retained until 72 hours, during which the embryos develop into hatchlings of about 6 mm.

Rearing fingerlings: 

a)       Nursery Ponds - Nursery phase

Three-day old hatchlings are reared in a nursery system for a period of 15-20 days till they become fry of 20-25 mm. Small earthen ponds of 0.02-0.1 ha are normally employed, though brick-lined or cement tanks are used in certain areas. The stocking density usually ranges from 3-10 million/ha in earthen ponds and 10-20 million/ha in brick or cement tanks. Though monoculture is advocated for nursery rearing, farmers often raise mrigal along with the other two Indian major carps. In these cases, the growth and survival of mrigal is higher than the other two. The other management measures include organic manuring and fertilization, and the provision of a mixture of rice bran and oil cake (1:1 w/w) as a supplementary feed. Survival normally ranges from 30-50 percent. Good pre-stocking nursery pond preparation includes control over predatory and weed fish, and insects.

Fingerling Rearing /production:

b)      Rearing Ponds

The fry from the nursery system are further raised to fingerling size (80-100 mm; 5-10 g). Earthen ponds ranging from 0.05 to 0.2 ha are commonly used. Although monoculture is advocated in the nursery phase, in fingerling rearing mrigal are stocked at about 30 percent and cultured along with other carp species at a combined density of about 200 000-300 000/ha. Feeding and fertilization regimes are similar to the nursery phase but vary according to the intensity of culture and the natural productivity. Overall survival in the fingerling rearing stage ranges from 60 to 70 percent; generally, mrigal has a higher survival level than catla and rohu. Fish are reared in this phase for 2-3 months, after which they are transferred to grow-out production systems.

On growing techniques: 

c)       Stocking pond

The grow-out culture of mrigal in polyculture systems is confined to earthen ponds and normal management practice includes predatory and weed fish control with chemicals or plant derivatives; stocking of fingerlings at a combined density of 4 000-10 000 fingerlings/ha; fertilization with organic manures like cattle dung or poultry droppings and inorganic fertilizers; supplementary feeding with a mixture of rice bran/wheat bran and oil cake; and fish health monitoring and environmental management. The grow-out period is usually one year; during which mrigal grows to about 600-700 g. Production is normally 3-5 tonnes/ha/yr, with mrigal contributing about 20-25 percent.

Mrigal also forms one of the important components in the sewage-fed carp culture system practiced in an area totaling over 4000 ha in West Bengal, India. In this form of culture, which includes multiple stocking and multiple harvesting of fish larger than 300 g, primary treated sewage is provided to the fish ponds as the main input. Even without the provision of supplementary feed, this system produces 2-3 tonnes/ha/yr. With supplementary feeding, this can be increased to 4-5 tonnes/ha/yr.

Harvesting techniques 

The bottom dwelling habit of mrigal hinders its effective harvesting by dragnet, the most common gear used in carp culture. Complete harvesting is possible only through draining. These harvesting difficulties make mrigal the least preferred species among the three Indian major carps for farmers. Cast nets are often used for partial harvesting in small and backyard ponds.

Handling and processing 

The species is mostly marketed fresh in local markets. However, long distance transport of mrigal with other carps packed with crushed ice at 1:1 ratio in rectangular plastic crates (60 cm x 40 cm x 23 cm) in insulated vans is often practiced in India.

1.3. d. Giant river prawn - Macrobrachium rosenbergii De Man, 1879 [Palaemonidae]

The freshwater macrouran species are usually referred to as “prawns” as distinguished from “shrimps”, the term used for the salt water forms. Most of these prawns are caridean crustaceans belonging to the family Palaemonidae. The famous giant freshwater prawn, Macrobrachium rosenbergii, is a good example of this group. It composes an important fishery in many natural freshwater bodies in several tropical and sub-tropical countries all over the world. Within recent years controlled hatching and grow out culture of marketable forms of this species have rapidly expanded in many countries and is still growing. This species has a fine delicate flavor and commands good market price in local markets as well as in foreign trade in both developing as well as in developed countries of the world. There are certain species that are of relatively higher economic importance because they grow to bigger sizes (length of 20 to 30 cm and weight of 200 to 300 grams).

There are a number of species of freshwater prawns in India of which four are of commercial importance (M. rosenbergii, M. malcolmsonii, M. villosimanus and M. mirabile), the first two are larger in size and are more desired. In 1979 the annual production amounted to about 350 mt for M. rosenbergii, 4 mt for M. malcolmsonii, 20 mt for M. villosimanus; and 125 mt for M. mirabile. The giant freshwater prawn Macrobrachium rosenbergii is the biggest species among the genus Macrobrachium (Fig. 3.10).In India M. rosenbergi is mainly harvested through natural fishery sites of Estuarine and rivers in west coast & east coast from Krishna-Godavari northwards.

Fig.3.10. External features of M. rosenbergii.

Distinctive features

1.       Body usually greenish to brownish grey, sometimes more bluish, darker in larger specimens.

2.       Males can reach total length of 320 mm; females 250 mm.

3.       Antennae often blue; chelipeds blue or orange. 14 somites within cephalothoraxes covered by large dorsal shield (carapace); carapace smooth and hard.

4.       Rostrum long, normally reaching beyond antennal scale, slender and somewhat sigmoid; distal part curved somewhat upward; 11-14 dorsal and 8-10 ventral teeth.

5.        Cephalon contains eyes, antennules, antennae, mandibles, maxillulae, and maxillae.

6.        Eyes stalked, except in first larval stage. Thorax contains three pairs of maxillipeds, used as mouthparts, and five pairs of pereiopods (true legs). First two pairs of pereiopods chelate; each pair of chelipeds equal in size. Second chelipeds bear numerous spinules; robust; slender; may be excessively long; mobile finger covered with dense, though rather short pubescence.

7.       Abdomen has 6 somites, each with pair of ventral pleopods (swimmerets).

8.       Swimmerets of sixth abdominal somite stiff and hard and, with the median telson, serve as the tailfin. Eleven distinct larval stages.

Historical background

The modern farming of this species has been originated in the early 1960. FAO expert Shao-Wen Ling, working in Malaysia, found that freshwater prawn (Macrobrachium rosenbergii) larvae required brackish conditions for survival. This discovery led to larval rearing on an experimental basis. By 1972 the Hawaiian team led by Takuji Fujimura had developed mass rearing techniques for commercial-scale hatchery production of prawn post larvae (PL). This development spawned the first commercial farms in Hawaii and elsewhere. Both Thailand and Taiwan Province of China became pioneers in modern giant river prawn culture. Global production had increased to over 2, 00,000 tonnes/yr by 2002.

Habitat and biology

1.    This species lives in tropical freshwater environments influenced by adjacent brackish water areas. It is often found in extremely turbid conditions.

2.    Gravid females migrate downstream into estuaries, where eggs hatch as free-swimming larvae in brackish water. Before metamorphosis into post larvae (PL), the planktonic larvae pass through several zoeal stages.

3.    After metamorphosis, PL assumes a more benthic life style and begins to migrate upstream towards freshwater.

4.    Larvae swim actively tail first, ventral side uppermost. From PL onwards prawns swim forwards, dorsal side uppermost. From metamorphosis onwards prawns can also walk, not only on the sub-stratum but also over damp areas including stones by river edges, up vertical surfaces (small waterfalls, weirs, etc.) and across land. 

5.    Larvae mostly consume zooplankton (mainly minute crustaceans), very small worms, and larval stages of other crustaceans.

6.    Post larvae and adults are omnivorous, eating algae, aquatic plants, molluscs, aquatic insects, worms, and other crustaceans.

7.    Males and females have different growth rates and males exhibit heterogeneous individual growth (HIG); these are vitally important factors in grow-out management. Three distinct male morpho types (and a number of intermediary types) exist: small male (SM), orange claw males (OC), and blue claw males (BC). The normal male developmental pathway is SM → OC → BC. BC males have extremely long second pereiopods; those of OC males are golden coloured; SM have small, slim, almost translucent claws.

8.    The type and behaviour of the males affects the growth rates of other prawns. The transition from rapidly growing OC to the slowly growing BC morphotype follows a "leapfrog" growth pattern. An OC metamorphoses into a BC only after it has become larger than the largest BC in its vicinity. The presence of this new BC male then delays the transition of the next OC to the BC morphotype, causing it to attain a larger size following its metamorphosis. BC males dominate OC males, regardless of their size, and suppress the growth of SM.

Culture method:

Fig.3.11.Production cycle of Macrobrachium rosenbergii

Breeding and Seed Production:

When required for hatchery use, female brood stock are usually obtained from grow-out ponds but also sometimes from capture fisheries. Normally, "berried" (egg-carrying) females are only used once. Commercial farms in tropical regions do not normally maintain captive brood stock for breeding purposes but adults are over-wintered indoors in temperate regions in order to stock ponds with PL as early as possible in the short grow-out season. The typical male to female ratio in brood stock holding systems is 1-2 BC males or 2-3 OC males per 20 females, at a total stocking density of 1 prawn per 40 liters. Within a few hours of copulation, fertilization occurs externally, as the eggs are transferred to the brood chamber beneath the abdomen. The eggs remain adhered to the female during embryonic development, which lasts about 3 weeks. At hatching, free-swimming zoeae are produced. Between 5 000 and 100 000 eggs are carried, depending on the size of the berried female. Eggs are orange until 2-3 days before hatching, when they become grey-black.

Fig.3.12. Berried females Macrobrachium rosenbergii

Hatching – Hatchery ponds:  Life Cycle

Collection of Seeds:

1. The seeds (juveniles) are collected, by means of scoop nets or traps made of a bunch of bushes, from the river estuary during both the low tide and the high tide. The seeds are then transported in open plastic containers (5' x 4').
2. Seeds may also be obtained from hatcheries where gravid females and berried females are induced to breed and to spawn, respectively.
3. Some seed (PL; juveniles) is obtained from the capture fishery where M. rosenbergii is indigenous, typically in the Indian sub-continent, but most is now hatchery-reared.
4. First stage zoeae are just less than 2 mm long and grow, through 11 larval stages, to almost 8 mm at metamorphosis into PL.
5. Individual metamorphosis can be achieved in as little as 16 days but usually takes much longer, depending on environmental conditions.
6. In commercial hatcheries, most larvae metamorphose by day 32-35 at the optimum temperature (28-31 °C). 
7. Larval rearing typically occurs in 12‰ brackish water, and hatcheries are either flow-through (where a proportion of the rearing water is regularly replaced) or recirculating (where a variety of systems involving physical and biological filters are used to minimize water use). Either type of hatchery may be inland or coastal. Inland hatcheries produce brackish water by mixing freshwater with seawater transported from the coast, brine trucked from salt pans, or artificial seawater. Some flow-through hatcheries use a "green water" system, which involves fertilization to encourage the growth of phytoplankton (mainly Chlorella spp.), which is believed to improve water quality and increase larval survival; others operate a "clear water" regime.
8. Feeding systems vary widely but typically include brine shrimp (Artemia salina) fed several times per day at first, reducing to a single daily feed by larval stage 10.
9. Prepared feed (usually an egg custard containing mussel or fish flesh, squid, or other ingredients) is introduced at stage 3 and its feeding frequency is increased towards metamorphosis. Some hatcheries are integrated with nursery and grow-out facilities.

Fig.3.13 Life history of M. rosenbergii.

Nursery Pond:

Although some farmers stock grow-out ponds with young post larvae (PL), many either purchase larger juveniles or rear PL in their own nursery ponds before transfer to grow-out ponds. Indoor nurseries are stocked at 1000-2 000 PL/m³, depending on whether substrates are used or not. Outdoor nurseries may be stocked with newly metamorphosed PL or with juveniles from an indoor nursery. Typically, stocking rates are 1000/m² PL, 200/m² small juveniles (0.02 g) or 75/m² of 0.3-0.4 g juveniles, but increased densities are possible if substrates are used. The rearing is best at about 28⁰ C. The feed includes a variety of items such as periphyton, lab lab eggs, custard, fish flesh, worms, a mixture of rice bran and oil cake, in equal parts, and Artemia/Moina. The last are produced by culture and the nauplii of these shrimps are very good food for the developing prawns. The stocking rate is usually 1 lakh per hectare. Lime, urea and superphosphates may also be used as fertilizers for the water. Management involves maintenance of good water quality and correct feeding. Rearing and stocking need different treatments. Rearing is done in nurseries to allow the post larvae (1 cm size) to grow to juveniles (2-3 cm size). For the nurseries, hapas, plastic pools, cement cisterns, fiber glass tanks etc. may be used. These are kept covered to avoid direct sunlight. Debris (unused feed, excreta and other matter) is continually siphoned off. Salinity is maintained at 4 to 5 ppt in the beginning and then is progressively increased to 14 ppt as larvae grow. The larvae are fed from the second day of the hatching on egg custard and live Moina/Artemia.

Fig.3.14. Schematic presentation of life cycle of M. rosenbergii.

On growing techniques 

Rearing Pond: Freshwater prawns are reared in a variety of freshwater enclosures, including tanks, irrigation ditches, cages, pens, reservoirs, and natural waters. These are commonly reared in earthen ponds. Normal rearing methods comprise various combinations of the formerly used "continuous" (ponds operated indefinitely, with regular cull-harvesting and restocking) and "batch" (single stocking, single harvesting) systems; these are known as "combined systems". Most systems involve monoculture, but the polyculture of freshwater prawns with finfish and sometimes other crustaceans also occurs, particularly in China (with carps).

Pond stocking densities in tropical monoculture vary widely. In extensive rearing systems (typically producing <500 kg/ha/yr), PL or young juveniles are stocked at 1-4/m²; semi-intensive systems (producing 500-5 000 kg/ha/yr) are stocked at 4-20 PL or young juveniles/m². Rarely, some small intensive systems also exist, which stock >20/m² to achieve >5 000 kg/ha/yr. In temperate areas with a limited rearing window of opportunity about 5-10 PL/m² or 4 juveniles / m² are stocked. These levels can be increased in presence of substrates.

Marketable size is reached in six months. A production of 45 kg to 75 kg per hectare is usually achieved.

Feeding: The prawns are fed on commercial or "farm-made" feeds, the latter being single or mixtures of ingredients, often extruded through mincers and either fed moist or (usually) after sun-drying. Feeds with 5 percent lipid and 30-35 percent protein are common place and an FCR of 2:1 or 3:1 is achieved with dry diets. Average growth rates depend on many factors, particularly the way in which male HIG is managed. The growth rate of SM is stunted by the presence of BC males; in their absence SM metamorphose into OC and ultimately into BC males. Thus the way in which grow-out ponds are managed (for example, the frequency of culling out large prawns, mostly males) influences total productivity.

Harvesting techniques 

Harvesting is carried out intermittently, catching the marketable-sized prawns (over 50 g). Yield, (in six months) is usually to the tune of 1000 kg/ha in monoculture and 500 kg/ha in polyculture.

Harvesting is either total (in "batch" rearing) or partial (in "continuous" or "combined" rearing). Total harvesting is achieved by gravity drain-down or water removal through pumping, while seine nets are used for regularly culling larger animals. Stretched knot mesh sizes of 1.8 cm are use to harvest small prawns and from 3.8-5.0 cm for large prawns. The time and frequency of harvesting depends entirely on the volume and characteristics (the animal size) of market demand.

Handling and Processing:

            Careful handling is essential from harvesting onwards to ensure good quality products. Freshwater prawns tend to go "mushy" if not handled and processed correctly. Firstly, it is essential to prevent prawns from becoming crushed during harvesting. Secondly, if they are not going to be sold live, they should be killed in a mixture of water and ice at 0⁰ C immediately (at the pond bank), and washed in chlorinated tap water. Prawns for live sale can be transported in aerated water at 20-22⁰C. Prawns sold fresh must not be kept on ice for more than 3 days. Prawns for sale frozen must be quick-frozen at -10⁰C (not simply placed in a "domestic" freezer) and stored at -20⁰C or below.

Review Questions:

Short Answer questions

1. Write the Biological name of Rohu.
2. Write the Biological name of Catla
3. Write the Biological name of Mackerel.
4. Write the Biological name of Prawn.

 Write short Notes on the following:

i)        Habit and habitat of Labeo rohita

ii)      Habit and habitat of  Catla catla

iii)    Habit and habitat of Cirrhinus mrigala

iv)    Habit and habitat of M. rosenbergii.

v)      Culture Methods of Labeo rohita

vi)    Culture Methods of Catla catla

vii)  Culture Methods of Cirrhinus mrigala

viii)Culture Methods of M. rosenbergii.

Long Answer questions:

1. Describe Habit, Habitat and Culture aspects of the Labeo rohita.
2. Describe Habit, Habitat and Culture aspects of the Catla catla .
3. Describe Habit, Habitat and Culture aspects of the Cirrhinus mrigala.
4. Describe Habit, Habitat and Culture Methods of M. rosenbergii.
5. Describe in general cultural methods for fresh water fishes

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