1. Seed in aquaculture
Seed as a major determinant for successful culture; growth and survival; role in production costs.
2. Different methods of seed production
2.1 Collection from natural sources
(a) Collection of fish, shrimp and prawn seed: life stages collected from the wild for culture; area suitable for seed collection - feeding and/or breeding grounds, favourable hydrographical conditions (current velocity, depth, salinity, turbidity, topography, etc); different types of gear employed, their mode of operation and relative efficiencies; seasons of occurrence of seed; sorting, holding or storage, conditioning and acclimatization.
(b) Collection of mollusc seed: areas and seasons for spat collection; different types of spat collectors - brushwood and mangrove branches, ropes, tarred sticks, tiles, threaded shells with spacers, plastic plates, etc.; handling and transport of mollusc seed.
2.2 Hatchery production of seed
(a) Brood stock:
(i) Wild-caught fish/prawn/shrimp - precautions in catching and transporting; state of maturity; selection of brood fish from catch; acclimatization; collection of berried shrimps and prawns.(ii) Farm-reared fish/prawn/shrimp - selection fo brood stock; age and size for spawning.
(iii) Care of brood stock, including feeding and segregation; sex-ratio required for breeding; effect of feeding and environment on gonadal maturity and spawning success; control of spawning by environmental manipulation and hormonal treatment.
(b) Spawning of fish:
(i) Methods of spawning - natural spawning, induced spawning - stripping; hormone injection (hypophysation); hormone injection with stripping.(ii) Hypophysation of fish - principles underlying hypophysation technique; reproductive physiology of fish in relation to hypophysation; homoplastic and heteroplastic pituitary administration; use of fish, mammalian and synthetic hormones and their combinations; dosages; methods of preservation of pituitary glands in liquid preservatives, drying and by ampouling; pituitary banks.
(iii) Spawning techniques employed, with particular reference to tilapias, carps, trout, catfishes, milkfish, mullets, groupers, gouramis and seabass.
(iv) Hybridization and selective breeding for production of better strains; hybridization for production of all-male progeny of tilapia; sex reversal techniques; principles of fish genetics and their application in hybridization and selective breeding of cultivable fishes.
(c) Spawning of crustaceans: maturation and induced spawning of shrimps and prawns; eye ablation (cauterization) of shrimps and prawns and attainment of maturity; spawning tanks and their operation.
(d) Methods of induced spawning of oysters, mussels and other molluscs: manipulation of temperature in oyster spawning.
3. Incubation and hatching
Different types of hatching installations (hatching ponds, tanks, hapas, jars, troughs, trays, etc.) and their relative efficiencies; suitable sources of water supply for hatcheries; importance of clean water, temperature and flow rate; aeration; open and closed systems; filters and biological conditioning; adhesive and non-adhesive eggs; bacterial and fungal infestations in hatcheries; ultraviolet and antibiotic treatments; effect of temperature/salinity regime on hatching time; size at hatching and viability of larvae; grading of larvae; transport of eggs.
4. Larval rearing
Different types of installations for early rearing of larvae; shape, size and colour of tanks; self-cleaning tanks; hygiene, water supply and lighting; density of stocking; feeding requirements of small-mouthed and large-mouthed larvae, vegetarian and carnivorous larvae; culture of food organisms, such as unicellular algae, protozoans, molluscan larvae, Artemia, rotifers, cladocerans, etc.; use of artificial feeds; feeding frequency and feeding rates; auto-feeders; physiological changes during metamorphosis of flat fish and the special care required; special requirements of mollusc larvae for settling; different types of spat collectors; production of cultchless spat; special requirements of prawn and shrimp larvae - salinity requirements and change of feed at various larval stages.
5. Transfer to nursery ponds
Acclimatization; time of transfer; grading; transportation; release; stocking rates.
6. Transportation
6.1 Live fish (spawn, fry, fingerlings and adults)
(a) Considerations in transport of live fish:
(i) Physiology of respiration in relation to physico-chemical dynamics of the transport medium.
(ii) Toxicology of biological waste products.
(iii) Action of chemical additives.
(b) Causes of mortality in transportation:
(i) Oxygen starvation.
(ii) Accumulation of toxins in the transport medium.
(iii) Hyperactivity, strain and exhaustion.
(iv) Diseases.
(v) Physical injuries.
(c) Conditioning of fish before transportation; special conditioning requirements of brackishwater fish for stocking in fresh water.
(d) Methods of packing and transport:
(i) Transport of hardy fish in baskets and buckets.(ii) Transport in open and closed systems - in open carriers with or without artificial aeration/oxygenation/water circulation; closed system - in sealed airtight carriers with oxygen; containers used - earthen pots, cans, wooden tubs, barrels, vats, polythene bags, live-fish carrier boats, specially equipped vehicles, etc.
(iii) Packing rates in relation to species, age, size, temperature, duration of transport, means of transport, nature of containers, climate, etc.; formula for packing rates.
(e) Use of chemicals: anaesthetics, antiseptics and antibiotics; dosages.
(f) Chemical control of osmotic pressure, pH and carbon dioxide.
(g) Use of coagulants for removing suspended/colloidal organic matter.
(h) Economics of live fish transport.
6.2 Live shrimps and prawns
Conditioning in cooling tanks; wet transport in open and closed systems; transport in cardboard boxes with sawdust and ice.
7. Economics of different methods of seed production
Practicals
Collection of fish seed, gears used and situations where used, shrimp and prawn larvae and juveniles and seed oysters/mussels from open bodies of water; induced breeding of selected species; hatching and larval rearing, producing at least one crop of fry; packing and transport of live fish (seed and brood fish) and prawns/shrimps.
