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Harvesting

Harvesting

  • It is done when the stocked fish have reached a marketable size, determined by customer preferences.
  • Most fish species attain this size between 7 and 12 months of stocking. 
  • Partial harvesting can be done when bigger fish are removed to allow smaller ones space to grow before total harvesting.

There are two fundamental harvesting methods that need to be considered by a farmer

1. Partial harvesting

2. Total harvesting

Partial Harvest

  • When different age group of the same fish species or different species combination are reared together in pond, the fish are bound to mature to table sizes at different times.
  • Partial harvest of pond should be done with appropriate mesh size.
  • Matured fish can be selected for market sale or family consumption while undersized ones should be returned to the pond.

Advantages

  • There is minimal wastewater discharge into the environment with associated metabolites and waste products.
  • The removal of larger stock from the system allows the smaller fish to increase in size more rapidly.
  • There is no production time lost because the pond has not been completely drained (and is therefore unable to be used).
  • Better able to control the needs of the marketplace.
  • A greener approach to water conservation.

Disadvantages

  • There may be increased water quality problems due to the accumulation of metabolites (e.g. ammonia, lower dissolved oxygen, nitrites, nitrates, etc.).
  • Minimal time available to make repairs to the pond.
  • Labour intensive.
  • High costs associated with repeated harvests (multiple labours).

Total Harvest

Total pond harvest from management point of view can be carried out at the end of a production cycle or in cases of emergency like diseases outbreak. 

  • A draw net or drag net is most suitable for total cropping of pond fish. 
  • Nets should be cleaned and spread in the sun to dry after each harvesting operation. This is to preserve and prolong their operational life span

Total harvesting in the fish pond

Advantages

  • The opportunity for the pond to be left fallow (i.e. time to dry and sterilise in the sun).
  • Can remove entire crop at once.
  • Cheaper labour requirements than partial harvest (one off).
  • Less physical damage to stock
  • More frequent repairs of pond if required.

Disadvantages

  • A non green approach to water conservation (i.e. the discharge of large volumes of water, and the pond then needs to be filled again).
  • Time-intensive.
  • Greater loss if stock should die during harvest or transport.
  • Fish will be multiple sizes and some stock may be too small for market requirements.
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