Questions and Answers
What is the primary food source used in the Lumut method of fish rearing?
Which species typically exhibits faster growth rates in monosex culture?
Which type of 'Lumut' is characterized as unbranched filamentous grass green alga?
What is a primary reason for implementing monosex culture in aquaculture?
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What happens to the 'Lumut' when it matures?
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What is the primary reason fertilization is more effective on sunny days compared to rainy days?
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Which fertilizer contains both nitrogen and phosphorus?
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How do warmer temperatures on sunny days affect microbial activity in relation to fertilizers?
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What is a consequence of using fertilizers during rainy conditions?
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Why do larger fish species generally grow faster than smaller species?
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What is the benefit of raising a combination of forage species in aquaculture?
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What is supplemental feeding in aquaculture?
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Why is feeding fish at maintenance rate generally not considered economical?
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What does feeding fish to satiation often lead to in aquaculture?
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What requirement do small fish have in terms of feeding compared to larger fish?
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Study Notes
Culture Systems and Methods in Aquaculture
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Culture Relative to Natural Food:
- Lablab method.
- Lumut method: Fish reared with filamentous grass green algae as primary food; may include supplemental feeds.
- Lumut: Filamentous grass green algae growing from the pond bottom to the surface.
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Types of Lumut:
- Chaetomorpha linum: Unbranched filamentous green alga (Lumutjusi).
- Cladophora: Branched filamentous green alga.
- Ulva intestinalis/tubulosa: Alga resembling young noodles, and fowl intestine in adult stage.
Methods of Culture Relative to Fish Sex
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Monosex Culture: Involves rearing either female or male fish exclusively to limit reproduction.
- Mostly applicable to tilapia.
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Advantages:
- Improved growth rates due to faster-growing sex leading to enhanced productivity and efficiency.
Principles of Aquaculture
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Commercial Inorganic Fertilizers:
- Common types: Urea (46-0-0), Ammonium sulfate (21-0-0), Triple superphosphate (0-46-0), and more.
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Efficient Fertilization:
- More effective during sunny days due to increased photosynthesis and nutrient uptake; less effective in rainy or overcast conditions.
- Higher temperatures enhance microbial activity aiding fertilizer absorption.
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Fertilization Risks:
- Rain can wash away fertilizers and reduce effectiveness.
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Species Growth Potential:
- Fish species with larger maximum sizes typically grow faster during their juvenile stages.
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Diversity in Feeding:
- Raising different species with varying food habits leads to better resource utilization and biomass accumulation.
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Increasing Carrying Capacity:
- Additional feeds (supplemental or complete) can support higher fish populations.
- Supplemental feeding enhances natural food availability, while complete feeding replaces the natural diet.
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Feeding Strategies:
- Maintenance feeding is non-economical as it does not promote growth.
- Overfeeding leads to waste and unnecessary costs.
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Yield Considerations:
- Maximum yield is limited by the carrying capacity of water in aquaculture systems.
- Higher fish density increases the risk of diseases and parasites.
Types of Culture Systems
- Pond Culture: Utilized for species such as milkfish, shrimp, seabass, etc.
- Cage/Pen Culture: Suitable for various fish, including tilapia and snapper.
- Raceway Culture: Commonly used for species such as milkfish and grouper.
- Recirculating Aquaculture Systems: Employed for tilapia, trout, and shrimp.
- Raft Culture: Specifically for shellfish like mussels and oysters.
Monoculture vs. Polyculture
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Monoculture Advantages:
- Higher yield due to optimal environmental conditions tailored for a single species.
- Simplified management and reduced risk of disease transmission.
- Potentially higher profits by responding to specific market demands.
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Monoculture Disadvantages:
- Increased disease risk, environmental degradation, and genetic homogeneity.
- Vulnerability to market fluctuations and changes in consumer preferences.
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Description
This quiz focuses on the principles of aquaculture, particularly the use of commercial inorganic fertilizers. It covers essential fertilizers such as urea, ammonium sulfate, and various phosphates, emphasizing their roles in enhancing aquatic productivity. Test your knowledge on how these fertilizers contribute to balanced aquaculture systems.
