Question 4
- Define the term stocking rate of a fish pond. [2 marks]
- List five maintenance activities that could be carried out on an old fish pond. [5 marks]
- It was observed that the colour of a fish pond water turned from light green to dark brown.
- What could this observation indicate?
- State four factors that could be responsible for the change in colour of the fish pond water.
- State four effects the change in colour of the pond water could have on Clarias spp. [9 marks]
- (i) Name two fishing gear that could be used in the partial harvesting of a fish pond.
(ii) Describe the method of ensuring total harvesting of a fish pond. [4 marks]
Observation
This question was attempted by many candidates and their performance was generally poor. Many candidates failed to interpret old and were stating general fish pond maintenance practices. In 4(c) many candidates cannot group the concept of a preamble or interpret it well. Candidates were referring more to algae bloom instead of algae kill.
The expected answer is as follows:
(a) Definition of the stocking rate of a fish pond
It is the number of fish that could be introduced into a given area or volume of
water (pond/tank) at a given time for the purpose of culture
(b) Maintenance activities that could be carried out on an old fish pond
- Flushing with water - Repair of leakages/cracks
- Clearing of weeds - Liming
- Fertilization - Draining/drying of pond bottom
- Removal of silt/mud/silting
(c) (i) What the observation indicates
- High turbidity
- Algal kills/excessive death of algae
- Water pollution
(ii) Factors that could cause the change in colour of the fish pond water
- Overfeeding of fish - Run off
- Erosion - Excess organic matter
- Mud/silt - Sewage
- Debris/agricultural waste/industrial waste
(iii) Effects of change in colour of pond water on Clarias spp
- Piping at the Surface of the pond water
- May cause disease
- Poor feeding
- Aestivation/hibernation
- Death
(d) (i) Fishing gear that could be used in partial harvesting of a fish pond
- Cast net - Hook and line
- Scoop net - Basket
- Drag net
(ii) Description of method of ensuring total harvesting of a fish pond
- The fish pond is completely drained
- The fishing gear or hand is used to collect fish at the bottom of
the pond