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, turbidity, topography, etc.); different types of gear employed, their mode of operation and relative efficiencies; seasons of occurence of seed; sorting, 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 - 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 - selection of 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, catfishes, trout, Heterotis and mullets.
(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; 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, and vegetarian and carnivorous larvae; culture of food organisms, such as unicellular algae, 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) Economies 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, 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.
