The development of aquaculture is influenced by many factors, which can be categorized into five major areas, each with several sub-factors. These factors and sub-factors can help identify indicators for potential increases in aquaculture production, guiding the selection of appropriate development programs.
Here are the five major factors affecting aquaculture:
1. Environment
This factor concerns the suitability of geographical areas for aquaculture development and includes three sub-factors:
- Physical environment: This determines whether a selected species can be grown successfully in a specific area without needing a controlled habitat. Key characteristics include temperature, rainfall, insolation, and water quality and quantity.
- Water Quality: This is crucial for fish growth and survival. Fish farming operations heavily depend on maintaining a healthy aquatic environment and sufficient fish food organisms. Poor water quality can lead to fish losses, while good water quality reduces disease treatment costs and improves fish taste. Water quality is influenced by physical, chemical, and biological factors.
A. Physical Factors:
- Water Depth: Influences temperature, circulation, and photosynthetic activity. An optimal depth of 1–2 metres is considered ideal for biological productivity, while very shallow water can overheat and harm fish.
- Water Temperature: Affects fish migration, reproduction, and distribution. Fish have defined temperature tolerance limits, with 20–32°C being optimal. Wide fluctuations stress fish, reduce growth, and necessitate stopping feed and fertilizer. Corrective measures include water replenishment or harvesting.
- Turbidity: Caused by suspended substances like clay, silt, phytoplankton, zooplankton, and sand. High turbidity reduces sunlight penetration and photosynthesis, acting as a limiting factor. It also lowers dissolved oxygen and can cause suffocation in fish and prawns due to sand accumulation in gills. Turbidity is measured with a Secchi Disc; an optimal range is 30–50 cm. High turbidity can be reduced by adding lime, alum, storing water in sedimentation tanks, or changing pond water if due to phytoplankton.
- Light: Greatly influences productivity and photosynthesis. In high turbid waters, light cannot penetrate to the bottom, causing vegetation to decay and produce harmful gases.
- Water Colour: Influenced by plankton, sand, organic particles, and metallic ions. Water for fish culture should be clear, light green, or blue. Colours like black, blackish green, dark brown, red, or yellow indicate poor conditions, often due to excess phytoplankton, bad pond bottom, acids, or high iron levels.
B. Chemical Factors:
- pH: Optimal range for pond water is 6.5–8, with levels below 5 or above 10 being lethal. pH fluctuates daily, being alkaline during the day and slightly acidic at dawn. Fluctuations are more pronounced with high phytoplankton and less hardness. A difference of more than 0.5 from morning to evening is undesirable. Low pH increases parasitic infections, while high pH makes ammonia toxic. Lime can be added for low pH, and new water or alum can reduce high pH and turbidity.
- Dissolved Oxygen (DO): Crucial for fish and prawn survival and growth. Oxygen enters pond water from atmospheric air and photosynthesis. DO levels are highest around 3 PM and lowest in the early morning. Optimum DO is 5–8 ppm. Levels below 5 ppm reduce growth and increase disease susceptibility, while less than 1 ppm can lead to death. More than 15 ppm can cause gas bubble disease. Precautionary measures to increase DO include disturbing the water surface or using aerators.
- Alkalinity: Caused by carbonates, bicarbonates, or hydroxides of various minerals. Optimal total alkalinity is 40–150 ppm and directly affects plankton production.
- Hardness: Caused by calcium and magnesium. Water with 15 ppm or more hardness is satisfactory, while less than 11 ppm may require liming for higher production.
- Carbon Dioxide (CO2): Produced during respiration and consumed during photosynthesis. Optimal level is 5 ppm. High CO2 lowers pH, making water acidic, and can lead to sluggishness and death in fish. Adding lime can reduce CO2 levels.
- Dissolved Ammonia (NH3): Produced from excreta, organic matter decomposition, and unfed high-protein feed. Optimal limit is 0.3–1.3 ppm. High NH3 increases pH, decreases dissolved oxygen, and can damage gills. Good management practices like avoiding excess feed and optimal stocking can reduce NH3.
- Hydrogen Sulphide (H2S): Produced in anaerobic conditions. It is toxic to fish and prawns, causing respiratory problems. It should be less than 0.05 ppm. Adding lime can help when H2S increases.
- Institutional environment: This includes governmental policy, planning, training programs, extension services, financial assistance, and controls. Political and economic stability at the national level significantly impact investment decisions and the success of aquaculture ventures.
- Social environment: Encompasses traditions, customs, religious beliefs affecting fish consumption, and the social acceptability of aquaculture as an activity. It also considers the stage of social and political development of local communities and the availability of infrastructure like supplies, services, housing, transportation, and communication facilities.
2. Space
This factor relates to the availability of suitable land or water space (in lakes, rivers, estuaries, or coastal bays) for aquatic farming. This space must be obtainable at an acceptable cost and allow for private control for private farming. This factor includes addressing competition for attractive areas such as residential or recreational waterfronts and established agricultural lands.
3. Technology
This factor covers the state-of-the-art for growing selected species (culture technology) and for preparing, preserving, and delivering products to consumers (product technology). It also includes the local availability of adequate information concerning both culture and product technology. Information dissemination, training, and extension service activities are vital for a sound technological basis for aquaculture development.
4. Production
This factor focuses on the application of technology and covers all activities directly related to growing the selected species. It includes four sub-factors:
- Planning and management: This involves developing the initial concept, species and site selection, capital formation, designing and constructing the farm, and overall business management. It requires personnel with technical and business management skills.
- Inputs: This refers to the availability of seed, feed, water, energy, and various materials and supplies at acceptable costs, as well as the logistics of providing these inputs.
- Operations: These are the day-to-day activities needed to grow fish, molluscs, crustaceans, or aquatic plants, harvest them, and prepare them for delivery. Trained personnel with technical skills, foremen, and trained labourers are essential.
- Costs: Emphasizes the importance of production costs in aquaculture development, as high costs due to location, culture systems, or operational inefficiency can make farms uneconomical.
5. Marketing
This factor covers processing, preservation, packaging, transportation, and sale of aquacultural products. It has four sub-factors:
- Planning and management: Includes selecting the product form, processing/preservation methods, and marketing strategy. It also covers the business management of marketing functions, such as scheduling harvesting to ensure continuous supply and minimize overproduction. Individuals with skills in product technology, marketing, and business management are required.
- Demand: Income and price considerations are major incentives for species selection. Aquaculture becomes more competitive as the cost of commercial fishing increases and wild stocks are fully utilized.
- Operations: Encompasses the day-to-day activities of processing, preserving, and packaging aquaculture products, and transporting them to various marketing levels. It requires personnel trained in product technology and quality control. For molluscs grown in contaminated water, depuration or holding in clean water is needed to protect consumers.
- Revenues: Together with production costs, revenues determine a fish farm’s profitability. Logical marketing strategies and market development can increase revenues, which in turn encourages aquaculture expansion.
Most of these sub-factors, except for the physical environment, can be modified by human activities to a greater or lesser degree. While extremely unfavorable physical environments might technically prohibit aquaculture, even moderately unfavorable ones can make it uneconomical due to the high cost of providing controlled habitats.
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REFERENCES
- Fish and Fisheries – B. N. Yadav
- A Textbook of Fish Biology and Fisheries – S. S. Khanna & H. R. Singh
- Introduction to Fishery Science – B. K. Tiwari & S. C. Pathak
