This article will discuss the principles, systems, and management of aquaculture and you’ll know the principles needed for aquaculture operation, identify and differentiate the characteristics of the aquaculture systems and recognize management for aquaculture operation including seed/adult fish transportation.
Contents:
- Introduction: Definition, potentials, scope, problems, risks, and threats of aquaculture.
- Principles and concepts: General principles of aquaculture, the concept of monoculture, polyculture, composite culture, hatchery, nursery, and grow-out operation.
- System and advancements in aquaculture: Extensive, Semi-intensive, and intensive culture, organic aquaculture, weed-based aquaculture, carp fattening, region-specific aquaculture, sustainable aquaculture.
- Management practices in pond aquaculture: Pre-stocking, stocking, and post-stocking measures emphasizing pond drying, pond liming, removal of aquatic weeds, removal of predatory and unwanted fishes/animals, pond fertilization, selection of species, supplementary feeding, sampling, partial harvesting and restocking, final harvest and marketing.
- Transportation of live fry and fingerlings and adult fishes: Equipment, water quality, handling, loading and stocking, shipping, use of anesthetics, and antiseptics during transportation.
- Common problems: Found in aquaculture management (water quality, disease, etc.) and their solution.
What is aquaculture?
Any means to improve fish production. FAO (1990) defined aquaculture as the farming of aquatic organisms, including fish, mollusk, crustaceans, and aquatic plants.
Aquaculture refers to three concepts:
- the organism and their farming environment
- means of enhancing production and
- ownership of the organism
What are the problems of aquaculture?
The problems of aquaculture are given below.
Technical:
- lack of quality seed
- lack of low-cost supplementary feed
- lack of inducing agents
- lack of need-based or region-specific aquaculture technologies
- water quality going back
- disease and parasite
Non-technical:
- Economical problem
- Social problem
- Multiple ownership
- Leased in and leased out
Lack of quality seeds: One of the important bottlenecks of aquaculture is the want for good quality fish seeds. Nowadays hatcheries have no principle. Hatchery operators are producing low-quality fish seeds through artificial breeding.
Lack of low-cost supplementary feed: Another abstraction for aquaculture is the want of an artificial balanced diet for cultivable species. Again price of the food is important, if it is costly then farmers would not be able to use it.
Lack of need-based or region-specific aquaculture technologies: Well-developed cultural technologies are scarce. Again, technologies suitable for marginal farmers cannot be suitable for large commercial farms.
What are the risks and threats of aquaculture?
The common risk we faced are given below –
- Occurrence of disease and parasite
- Natural disaster
- Unavailability of supplementary foods
- Unavailability of labor
- Price fall in market
- Poisoning
Occurrence of disease and parasite: By natural or man-made causes, fishes are attacked by various diseases and parasites. Generally, in polluted and untidy water bodies, fish are often attacked by disease and parasites. Sometimes, the great mortality of fish occurs due to disease and parasites.
Natural disaster: A natural disaster is one of the major risks of aquaculture. The common natural disaster is a flood, droughts, etc. Approximately, 30-40 districts are flooded every year. As a result farmers of those areas become impoverished.
Unavailability of supplementary feed: Supplementary feed is very important to aquaculture. It helps to increase fish production. But, when it goes unavailable or the price goes high, then it is not easy to provide by the farmers. So, the unavailability of supplementary feed is a great risk to aquaculture.
Poisoning: Poisoning is one of the major risks of aquaculture. Sometimes, a water body gets poisoning by some group of people from enmity or by industrial wastes. A few drops of endrin kill all the organisms in a pond.
Price fall in the market: Generally, farmers invest their money in aquaculture to get a profit but sometimes, unfortunately, they do not get a profit because of the price fall of that fish in the market. So, price fall is a major risk.
How can you minimize the risk?
Integrated farming: Integrated farming may be a way to minimize the risks of aquaculture. For example, the culture of fish with poultry. The fecal matter of poultry is used as feed for fish. So, the cost of aquaculture reduces due to not having a supplementary feed.
More crops: The other way to minimize the risks of aquaculture is the cultivation of more crops with aquaculture. The margin of the pond can be used for cultivation such as vegetables, Calabash, Cowpea, etc. These are the extra income source that may help to minimize the risk of aquaculture.
Threat: When the risks of aquaculture are excessive and continually affect aquaculture, then they turn into a threat to aquaculture. Such as –
- Long-lasting of flood
- Pestilence of disease
- High price fall in the market
- Walk out by the labor or unavailability of labor
- Any restriction of government. For example, African Magur is highly destructive to the environment and so it has been banned by the government.
The potential of aquaculture
Enhancement of fish production: At present, the government has taken many initiatives to improve fisheries’ resources. In the fiscal year 2008 – 09 the total fish production was 27.01 lac M.T. But in the 2012 – 13 fiscal year, it has reached 34.10 lac M.T. If this flow of obsessive going on, we will have 45.52 lac M.T of fish production by 2022 – 21.
Employment for rural peoples: About 11% of the total population of our country is directly or indirectly connected to the fisheries and fisheries sector. For last 5 years above 6 lac, poor people have their employments at this sector. So, aquaculture has a great potential to create employment for rural people.
Exportation of fish and fisheries products: The fisheries sector has a great contribution to this. At present, the sector contributes 4.37% of the total GDP and one-fourth (23.3 7%) of the total agricultural GDP. In the 2014-15 fiscal year, we had 1 billion US dollars by exporting shrimp and processed fish products.
Artificial fish pond and fish culture: The population of our country is increasing day by day. So, it needs more habitats for the increasing population. Every year, many ponds, and lakes are filled with mud for habitation. So, fish production is hampered. But, nowadays fish are cultured in an artificial reservoir. It has been possible due to improved aquaculture technologies. So, aquaculture has a great potential to meet fish demand for the increasing population.
Scope of aquaculture:
The major scope of aquaculture is that we have many water bodies for aquaculture. Here given a data on water bodies –
Internal water bodies:
| Open Waters | Area (hectare) |
| River and estuary | 8,53,863 |
| Sundarbans | 1,77,700 |
| Beel | 1,14,161 |
| Kaptai lake | 68,800 |
| Flood plain | 27,02,308 |
| Total | 39,16,828 |
| Closed water | Area (hectare) |
| Ponds | 3,71,309 |
| Secondary water bodies | 1,30,488 |
| Lakes | 5,488 |
| Shrimp hatchery | 2,75,274 |
| Total | 7,82,559 |
Create employment for unemployed youth: The second major scope of aquaculture is employment for unemployed youth. Nowadays the number of unemployed youth is increasing day by day. We have much more educated youth than required for the number of job sector. Aquaculture creates opportunities and gives solutions to unemployment.
Significance of aquaculture:
Fish as food: Fish is felicitated as a major source of protein worldwide. It supplies food and nutrients. Above 60% of the animal protein comes from fish. Our staple food is fish with rice.
Nutritional requirement: In our country per capita, the protein requirement is 56 gram of which 52 gram comes from fish. Fish has a great nutritional value. In fish, protein, lipids, vitamins, and minerals contain such a combination that is helpful to keep us fit.
| Comparison of nutrients in 100g of white fish or oily fish | ||
| Nutrient | Whitefish | Oily fish |
| Energy (Kcal) | 111 | 203 |
| Protein (g) | 23 | 23 |
| Fat (g) | 1 | 12 |
| Cholesterol (mg) | 86 | 77 |
| Vitamin B12 (g) | 4 | 13 |
| Phosphorus (mg) | 267 | 303 |
| Selenium (g) | 44 | 47 |
| Omega – 3 (mg) | 509 | 2014 |
In addition, mola fish is a great source of vitamin – A which helps us prevent a disease called “Night Blindness”. During the antenatal period, pregnant women need to feed mola fish, Magur, and other highly proteinous food. But, unfortunately, most of us are ignorant about it. That is why we suffer from malnutrition. The poor also suffer from under-nutrition conditions as they can’t supply themselves.
Employment generation: Above 11% of the total population directly or indirectly are connected with the fisheries sector for their livelihood. Last five years, above 6 lac poor people have their employments in this sector. At present, above 80% of the total employee of the fish processing factory are women. So, this sector has a great potential to utilize women’s power.
Foreign earning: The fisheries sector has a great contribution to this. At present this sector contributes 4.37% of the total GDP and one-fourth (23.37%) of the total agricultural GDP. In the 2014-15 fiscal year, we had 1 billion U.S dollars by exporting shrimp and processed fish products.
Environment management: We have many ponds, lakes, submerse, and canals that are used unproductively years after year. It harms the environment. It damages the ecosystem of that environment. If we reform those ponds, lakes, submerses, and Ken to fish culture, the environment will develop, and above all, we will have proper utilization of our water resources.
What is sustainable aquaculture?
Suitable aquaculture means –
- Technology should be sound
- Less environmental pollution
- It should be economically viable
- The Technologies should be socially acceptable
Low-cost aquaculture:
- Fertilizer feed-based aquaculture
- Weed based aquaculture
- Organic aquaculture
Fertilizer feed based: Fertilizers may be organic or inorganic. Organic fertilizer such as cow dung, compost, poultry fecal, etc. On the other hand, inorganic fertilizers such as Urea, TSP (Triple Super Phosphate), DAP (Di-ammonium phosphate), etc. Both forms of fertilizer are very beneficial to aquaculture but inorganic forms of fertilizer have some problems.
Urea is a volatile fertilizer. On the other hand, DAP is a stiff infusible fertilizer. Both types of fertilizer help to grow up phytoplankton rapidly. So, phytoplankton feeder fishes such as silver carp grow rapidly. It is a very useful low-cost aquaculture technique.
Organic fertilizer requires a high quantity but low-cost fertilizer. On the other hand, inorganic fertilizer requires low quantity but high-cost fertilizer.
Weed-based: Some groups of phytophagous fish species such as grass carp are mainly fed on aquatic weeds, macrophytes, etc. They take these as their main food but cannot digest them properly. Their semi-digested fecal matter is released into the water body and served as feed for other groups of fish species. So, weed-based aquaculture is one of the low-cost aquacultures.
Organic aquaculture: Organic aquaculture means no inorganic materials/chemical salts can be used night from a hatchery production of seed material to its actual aquaculture in water sheets. Only natural organic materials of plant or animal origin and not any inorganic chemicals can be used at any stage of aquaculture.
Certain chemicals are used in the shipment of seeds and also in fish feeds and in the treatment of various diseases. In organic aquaculture, it is not allowed.
Carp fattening: Carp fattening is the concept of the growth of fish quickly within a shorter period by releasing yearling offspring in the pond.
Region-specific aquaculture:
- The aquaculture technologies developed for the specific agro-ecological zone are called region-specific aquaculture.
- There is 30 Agro-ecological zone in Bangladesh.
- The Soil and water parameter are found to be varied in these agro-ecological zones.
- For example, the nutrient in NPK releases if the alkalinity remains above 20 PPT in an agro-ecological zone.
Monoculture: The culture of only one species is termed monoculture.
- Advantages of monoculture: We can be able to research a specific species.
- Disadvantages of monoculture: Feeds are not used properly.
Polyculture: Culture of different species at the same time. For example, the culture of silver carp with Matrigel.
- Advantages of polyculture: Ensure the full utilization of natural feed of a niche.
- Disadvantages of polyculture: We will fail to be culture-specific species.
Surface feeder/Low-level fish: Katla, Silver carp, and bighead carp.
Column feeder/Low-level fish: Rui/Rohu
Bottom feeder/Low-level fish: Mrigel, Kalibaus, mirror carp.
Fish of all levels: Grass carp, punti
Composite aquaculture:
Composite aquaculture is one kind of polyculture where species are stocked at a particular ratio.
Hatchery: A place where fish seeds are produced through induced breeding techniques.
The primary stages of offspring are observed in a hatchery.
Spawn – Fry – Fingerling – Yearling
Fry: When they have developed to the point where they are capable of feeding themselves.
Fingerling: When they have developed scales and working fins, the transition to a juvenile fish is complete and it is called fingerling. Fingerlings are typically about the size of a finger.
Overwintered fry: Overwintering is the process by which try offspring pass through or wait out the winter season. These types of fry are called over-wintered fry. They are very hardy and disease resistant and grow quickly.
Broad fish: Able to produce offspring.