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Class 9, Science, Chapter-12, Lecture-9, Fisheries (Notes)

FISHERIES:

Establishments connected with capture, preservation, exploitation and utilization of various types of fishes, prawns, lobsters, oysters etc are termed as fisheries.

Two Types (on the basis of product):

  1.  Fin fishery:
    Establishments connected with capture, preservation, exploitation and utilization of cartilaginous and bony fishes are termed as fin fisheries.
  2. Shell Fishery:Establishments connected with capture, preservation, exploitation and utilization of shellfish (prawns, molluscs) are termed as shell fisheries.

Two Types (on the basis of mode of obtaining fish):

  1. Capture fishery:
    Establishments connected with capture, preservation, exploitation and utilization of fishes and shellfishes obtained from natural resources are termed as capture fisheries.
  2. Culture Fishery (Pisciculture):
    Establishments connected with capture, preservation, exploitation and utilization of fishes and shellfishes obtained by cultivating, rearing and harvesting in fish farms are termed as culture fisheries.

Three Types:

  • Monoculture:
    Cultivating, rearing and harvesting of a single species in fish farm is termed as monoculture.
    Example: Catla, Lobeo
  • Monosex Culture:
    Cultivating, rearing and harvesting of only one sex of a single species in fish farm is termed as monosex culture.
    Example: Tilapia, Salmon
    Advantage: All the energy of the fishes is utilised for growth and not for reproduction.
  • Polyculture (Composite Fish Farming):
    Cultivating, rearing and harvesting of few selected species having different feeding habits in fish farm is termed as polyculture.
    Example: Chinese carp + Grass carp + Big head carp
  • Catla + Rohu + Mrigala (3 : 3 : 4)
    Advantages:
  • All types of available foods are utilised as different fishes have different feeding habits.
  • The food available in all the zones of the water-body is utilised.
  • Different types of fishes can be reared in the same time.
  • Yield is very high due to optimum utilisation of resources.

Two Types (on the basis of habitat):

  1. Marine fishery:
    Establishments connected with capture, preservation, exploitation and utilization of fishes and shellfishes obtained from sea water or by cultivating, rearing and harvesting in artificial fish farms in sea water are termed as marine fisheries.
    Examples: Sharks, Rays, Prawns, Lobsters, Crabs, Oysters, Octupus
  2. Inland Fishery:
    Establishments connected with capture, preservation, exploitation and utilization of fishes and shellfishes obtained from fresh water or by cultivating, rearing and harvesting in artificial fish farms in fresh water are termed as inland fisheries.

Steps of Pisciculture Management:

  1. Selection of species with the following qualities
    (i) Easy to breed
    (ii) Good flesh quality
    (iii) Faster growth
    (iv) Health
  2. Collection of seeds in the form of Eggs, Fry (Freshly hatched) or Fingerlings (small young fishes) from natural water system or by induced spawning.
  3. Harvesting, Processing and Preservation

Process of Induced Spawning:

  1. Injection of synthetic hormones such as ovaprim, ovatide and nova.
  2. Injected males and females are kept in a breeding hapa in the ratio of 2:1 in the evening.
  3. Spawning (development of unfertilised eggs) is completed by the morning.
  4. Females lay unfertilised eggs and males shed sperms to fertilise the eggs.
  5. Fertilised eggs are transferred to hatching hapa for 2-3 days.
  6. Fry (freshly hatched fishes) are transferred to nursery.
  7. Fingerlings are reared in rearing ponds for 3-4 months.
  8. Advanced fingerlings are transferred to stock ponds.