Introduction: Hello aqua farmers today we are here with a great informatgion of Shrimp aquaculture in India. Shrimp aquaculture has come under increasing criticism due to reported adverse social and environmental impacts, questionable sustainability because of disease outbreaks, and sometimes irresponsible growth objectives or practices. The considerable amount of land necessary for extensive and semi-intensive farming has resulted in the significant conversion of coastal wetlands into shrimp ponds, with local impacts on biodiversity and natural resource use. These problems are related mostly to the overly rapid development of a fledgling industry with inadequate technical knowledge and development planning, and although they have been exaggerated in many instances, they should nonetheless be addressed.
A step by step guide to Shrimp aquaculture in India
India as the second-largest country in shrimp aquaculture production in the World, the share of the brackish-water sector includes the culture of shrimp varieties primarily, the native giant tiger prawn, Penaeus monodon and exotic white-leg shrimp, Litopenaeus vannamei. Today, L. vannamei species is the most extensively farmed crustacean species in the World. Shrimp aquaculture has been portrayed as having high feed conversion ratios (FCR) that impair wild fish stocks to feed Western demand; mangroves are destroyed to make new ponds; antibiotics threaten human health; wastewater leaves agricultural lands and coastal waters barren; and the boom and bust history of sector has left an image of greed and collapse.
The farmer’s choice of shrimp aquaculture techniques is influenced by;
- Land, water, power availability and cost
- Transportation and cost
- Credit availability and cost and repayment terms
- Labor availability and cost
- Feed, Fertilizer, Probiotics availability and cost
- National planning regulations & environmental controls
- Import or export costs
- Proximity to the existing market
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Site selection for Shrimp aquaculture in India
The selection of a suitable site always plays a major role in shrimp aquaculture farming. The selection of a site for shrimp farming mainly depends on topography, ecosystem, meteorological and socioeconomic conditions about farm design, species compatibility. Factors affected for site selection for shrimp culture;
The type of soil condition is the most critical in site selection since the shrimp will spend most of its time on the pond bottom during the culture period. Usually, clay or loam-based soil containing more than 90% clay and pH level between 6.5-8.5 is preferable. Sites with sandy or silty soil must be avoided due to their porous nature that may lead to erosion, seepage of water and easy infiltration of waste into the soil. Before the construction of ponds, samples of the soil must be taken randomly from 5-10 spots at the surface and at 1 meter deep and sent to a laboratory for the analysis of soil texture and pH. Such information will be useful during pond construction and preparation.
Mangrove or acid sulfate soils are not suitable for shrimp pond culture due to their high organic matter contents and acidic nature than that require a high water exchange rate and low stocking density. A pond built on mangrove soil will encounter the problems of hydrogen sulfide and ammonia accumulation in the pond bottom. In the acid sulfate soil areas, the soil will increase high acidity when dried and then flooded which will lead to difficulty in stabilizing the pH level of the pond water and inducing the growth of plankton during the culture stage.
The tidal characteristics of the proposed site must be known. Knowledge of these tidal characteristics is of extreme importance in determining pond bottom elevation of a dike, slope ratio, and drainage system.
Areas best suited for shrimp farming must have moderate tidal fluctuations preferably 2–3 meters. In areas where this is greater than 4 meters, the site can show uneconomical to develop or operate as large and high pond dikes will be essential. In areas where the tidal range is less than 1 meter, water management will be expensive requiring the use of pumps.
A salient point to consider about tidal vary is the knowledge of the occurrence of the highest high and lowest low water levels. This must be known so that the size and height of the perimeter dike can prevent flooding. Also, the direction and strength of water current must be known for provisions on dikes construction to reduce erosion.
Lastly, the proposed area should not be adversely affected by any industrial or agricultural pollution.
It is essential to have detail topography of the selected site for pond design and farm layout. Coastal sites where the slopes run gently towards the sea are easier for pond development requiring less financial inputs because excavation is minimal. The filling and draining of water likewise are simply facilitated by gravity.
In areas where the above conditions are not obtainable, the use of mechanical pumps may have resorted. It can prove uneconomical if the site to be developed would require diking material to be transported from outside the chosen area.
Importance of good on-farm shrimp aquaculture management
This ‘on-farm shrimp aquaculture management’ covers all those activities conducted by shrimp farmers related to the handling, storage, and application of shrimp feed on the farm; shrimp feeds include commercially manufactured feeds, farm-made feeds and live natural food items.
In general, the nutritional performance of a shrimp feed mainly depends upon five interconnected factors. They are;
- The nutrient content of the diet being fed and the physical properties and water stability of the diet being fed;
- The transportation and storage of the diet before feeding on the farm;
- The feeding process employed for feed application and usage on the farm; and
- The farming system, stocking density, water management and availability of natural foods
- Circular water treatment systems and more self-contained systems decrease discharge significantly, reducing risks of disease spread.
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Farmed shrimp aquaculture species
Some cultivable species are more suitable for large-scale, commercial aquaculture rather than for small-scale operations, as exemplified by the high-value shrimps, the production of which can hardly be undertaken profitably on a small scale. And, some species are best cultured using specific types of enclosures. Penaeid shrimps are best cultured in fish ponds rather than in fish pens and certain species are acceptable in certain countries.
The selection of species depends on several factors that are the availability of suitable sites, the biological characteristics of the indigenous, and exotic species.
There are several species of shrimp and prawn, only a few of the larger ones are farmed, all of which belong to the family of penaeids (family Penaeidae) and within it to the genus Penaeus. Many factors should be considered when a farmer is deciding which species of shrimp he should culture.
- Pacific white shrimp (Penaeus vannamei)
- Giant tiger prawn (P. monodon)
- Indian white shrimp (P. indicus)
- Kuruma shrimp (P. japonicus)
- Giant Freshwater Prawn (Macrobrachium rosenbergii)
Shrimp aquaculture farm techniques
Closed Recirculation Systems (CRS)
A closed recirculation system or CRS can be used in existing semi-intensive systems and super-intensive systems. The farming of shrimp aquaculture in closed recirculation systems involves the installation and operation of recirculation for the water being used during the grow-out period. The culture water is always re-used and treated to regenerate a water quality suitable for the shrimp or fish to grow.
A closed recirculation system can consist of different components;
- Culture basin
- Solids filter removing suspended particles
- Denitrification reduction of nitrate products and stabilize the pH level and alkalinity
- Reservoir and Biofilter, nitrification removing organic matter and ammonia products
- Sludge removal and discharge
Integrated manure denitrification system
This system is fed with the concentrated waste flow from a shrimp or fish farm system containing dissolved and particulate faecal organic waste, bacterial flocs and inorganic compounds. In the sludge of the bioreactor, the faecal particulate carbonaceous waste is digested by the denitrifying bacteria and effects in;
- The production of bacterial biomass
- Reduction of nitrate into nitrogen gas, production of carbon dioxide
- Production of alkalinity
- Mineralization and reduction of the sludge.
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The particulate waste in the sludge bed serves as media for the denitrifying bacteria to grow on. Sludge leaves the bioreactor through a patented filtration unit and can be discharged from the system when essential. The choice of system depends on the species that are cultured but may consist of a hybrid system utilizing a combination of heterotrophic, autotrophic bacterial flocs and clear water supported by probiotics.
Shrimp aquaculture feed handling and storage
Feed conversion ratios are steadily improving and experts report that shrimp do not require a fish diet anymore, though growth rates often remain higher when at least some fishmeal is included. Processing byproduct meal is becoming a common replacement in fishmeal, mainly for countries with large seafood processing industries.
Shrimp feeds are composed of formulated mixtures of ingredients or essential nutrients (e.g. proteins and amino acids, fats and fatty acids, carbohydrates and sugars, minerals and trace elements, and vitamins) that are prone to deterioration and loss or destruction upon prolonged storage before feeding.
Nutrient losses and destruction may affect from the prolonged exposure of finished feeds to unfavorable storage conditions on the farm, either due to inadequate shelter and protection of the feed from the natural elements (light, heat, humidity, air and water) and due to microbial or pest infestation (bacteria, fungi, insects, rodents). Under the above ambient conditions, feed shelf life must be not more than two to three months under tropical/warm (20–30°C) storage conditions and not more than four to six months under temperate/cold (10–20°C) storage conditions.
Fertilization required for shrimp aquaculture in India
In any shrimp aquaculture, the pond should be fertilized with either organic or inorganic fertilizer to stimulate the plankton bloom to provide shade to the pond bottom and utilize the nitrogenous waste and phosphate wastes within the pond. The shade will prevent the growth of harmful benthic algae. The sun-dried chicken manure is the most regular organic fertilizer to be used in the amount of 200-300 kg/ha. The manure should be soaked in water for 24 hours before it is spread over the surface of the water.
Inorganic fertilizers, for example, urea (46% N) and compound fertilizers like, ammonium phosphate (16:20:0) or those with N:P:K combination of (16:16:16) can be used at 20-30 kg/ha. The fertilizer must be dissolved in water before it is spread over the surface of the water to avoid precipitation of the fertilizer onto the pond bottom, which will enrich the soil and accelerate the development of benthic algae.
After fertilization, the plankton must bloom within a few days and the color of the water becomes slightly green. The fertilizer, either the organic or inorganic, must be applied daily in the pond at 5-10 % of the initial amount to maintain the plankton bloom. If the plankton has not bloomed within a few days, additional fertilizer should not be applied, but plankton-rich or green water from the reservoir must be added.
Water quality management for Shrimp aquaculture in India
In any shrimp aquaculture, the management of water quality is of primary consideration particularly in ponds with higher stocking rates. Degradation of water quality is detrimental to shrimp expansion and survival. Good quality water is generally defined as the fitness or suitability of the water for survival and growth of shrimp.
Maintenance of good water quality is necessary for both survival and optimum growth of animals. Water treatment is a very important step during pond preparation for the maintenance of good water quality at a later stage.
The pH level of the pond water is indicative of its fertility or potential productivity. Water with pH ranging from 7.5 to 9.0 is generally regarded as suitable for shrimp production. The growth of shrimps is retarded if the pH level falls below 5.0. Water with a low pH level can be corrected by adding lime to neutralize the acidity.
The water of excessive alkalinity (pH values > 9.5) may be harmful to shrimp growth and survival. In ponds that are excessively rich in phytoplankton, the pH of pond water generally exceeds 9.5 during the late afternoon. However, at daybreak, the pH is generally lower. Excessive plankton increase can be corrected by water exchange.
Environmental impacts associated with shrimp aquaculture in India
The main environmental impacts associated with shrimp aquaculture farming, and ways in which specific impacts can be reduced or mitigated.
The actual or potential environmental impacts of shrimp aquaculture farming fall into the following categories;
- Destruction of natural habitat (through direct conversion);
- Abstraction, contamination, and salinization of groundwater;
- Organic matter and nutrient pollution;
- Harvest of broodstock and wild post-larvae (PL);
- Introduction of exotic species;
- Abandonment; and
- Use of fishmeal in feeds.
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