Fisheries and Marine Industries
Scope
Fisheries and Marine Industries tests aquaculture, fishing operations, marine environment, seafood handling, and marine safety. Questions often require interpretation of water quality, feed efficiency, stock density, or cold-chain practice.
Core rules
- Dissolved oxygen, temperature, pH, and ammonia are key water-quality variables; low oxygen stresses fish and reduces feeding.
- Stocking density should be expressed with biomass and water volume, not only number of fish.
- Feed conversion ratio (FCR) = feed consumed / live weight gain; lower is generally more efficient.
- Seafood safety depends on rapid chilling, clean handling, and separation of raw and cooked products.
- Marine operations require weather awareness, personal flotation, and radio communication procedures.
Worked example
A tank holds 20 m3 and the target stocking density is 15 kg/m3. Allowable biomass = 20 x 15 = 300 kg. If average fish weight is 0.5 kg, the tank can hold about 300 / 0.5 = 600 fish. Reasoning: density is a biomass limit, so convert fish number to total weight before deciding whether stocking is acceptable.
A farm uses 120 kg feed and gains 80 kg of fish. FCR = 120 / 80 = 1.5. If the target is 1.2, the farm is less efficient than target.
Traps
Confusing FCR with feed efficiency (gain/feed) reverses the interpretation. Counting fish without weighing them ignores biomass. Ignoring dissolved oxygen during high feeding or warm weather can cause mortality. Leaving seafood in the danger zone shortens shelf life and risks food poisoning.