Principles Of Aquaculture PDF

Principles of Aquaculture Principles of Aquaculture 1. All fish are dependent for food directly and indirectly upon aquatic plants. Indirect: Plant/vegetation zooplankton Fish (carnivore) Direct: Plant/vegetation...

Principles of Aquaculture Principles of Aquaculture 1. All fish are dependent for food directly and indirectly upon aquatic plants. Indirect: Plant/vegetation zooplankton Fish (carnivore) Direct: Plant/vegetation Fish (herbivore) Principles of Aquaculture 2. The weight of fish which can be produced is dependent upon the ability of water to produce the necessary plants. Photosynthetic Activity Sunlight 6CO2 + 6H2O C6H12O6 + O2 Nutrients Ecological groupings of different Requirements of Aquatic Plants types of plants: 1. Carbon dioxide 1. Phytoplankton 2. Sunlight 2. Microphytic algae 3. Ideal temperature ▪Filamentous algae 4. Nutrients from soil ▪Periphyton 5. Dissolved nutrient ▪Benthos 6. Water 3. Macrophytes (Higher aquatic plants) Principles of Aquaculture 3. The microscopic are the principal food producing plants for most cultured organisms. Reasons: 1. High nutrient content, 20-50% protein per dry weight. 2. Mobility – easily distributed by wind and current. 3. Easy to ingest and digest because of their size. 4. Faster proliferation/reproduction 5. Short life cycle – faster rate of turn-over of nutrients. Principles of Aquaculture 4. The more fertile the water, in the absence of rooted vegetation, the denser the phytoplankton concentration. The Shallower light penetration, lower photosynthesis levels reducing oxygen production and often primary productivity. Aquatic Macrophytes - large aquatic plants - A plant that is normally found in nature growing in association with free-standing water, whose leaves is at or above the surface of the soil. Almost all were originally land plants and are secondarily aquatic. There are also some ferns, mosses, liverworts and large algae. - undesirable plants - interfere with light penetration - this should be eliminated in the pond Principles of Aquaculture Aquatic Macrophytes Advantages VS Disadvantages Maintains water quality Restricts movements of fish Serves as shelter Prevents adequate light penetration Substrates for food Lowers pond productivity Causes oxygen depletion Compete with the natural food May cause mass mortalities of fish Makes harvesting difficult May become a public health hazard In net cages, it can reduce water exchange and thus affect the water quality within the cages. Adds to the operational cost  Principles of Aquaculture Types of Aquatic Macrophytes 1. Floating unattached (duckweed, water hyacinth, water lettuce) – plants that float with most of the plants body above the water surface.348bpkg u027_jpg Azolla Water Lettuce Azolla pinnata Pistia stratiotes L. Duckweed Wolffia Wolffia spp. Water Hyacinth Duckweed Eichhornia crassipes Lemna minor  Principles of Aquaculture Types of Aquatic Macrophytes 2. Floating attached (water lilies and pond weeds) – plants having their leaves floating on the water’s surface but their roots are anchored in the substrate. Water Lily Nymphaea sp.  Principles of Aquaculture Types of Aquatic Macrophytes 3. Submersed (water milfoil, elodea, wild celery, and coontail) – plants that spent their entire life cycle under water with the possible exemption of flowering beneath the surface of the water. Vallisneria sp. (Ballayba: Ilokano term) 4. Emergent (cattail) – plants whose roots and basal portions grow beneath the surface of shallow water but whose leaves and stems are borne primarily in the air. Cattail Principles of Aquaculture Methods of Aquatic Plant Control: A. Prevention of infestation of weeds ▪ Maintain a depth of 0.75 – 0.9 m to discourage the growth of marginal weeds. ▪ Reduce accumulation of silt by preventing drainage of run-off from fertile land areas ▪ Regular de-silting of ponds ▪ Erecting barriers or mesh filters ▪ In cages, use nettings which are treated with anti- fouling chemicals. ▪ Culture macrophyte-eating fishes such as grass carp. Principles of Aquaculture Methods of Aquatic Plant Control: B. Manual methods For floating weeds C. Mechanical methods Weed cutter – for large individual ponds D. Chemical methods herbicides – rapid results but lethal to cultured fish 2,4 D (2,4 – dichlorophenoxyacetate) ❖ For floating and emergent weed Diquat (6,7 – dihydrodipyrido (1,2-a : 2’1’-C) pyrazidiinum salt) ❖ For emergent, floating and submerged weeds Simazine (2-chloro-4,6 bis (ethylamine)-triazine) and copper sulfate ❖ For filamentous algae Principles of Aquaculture 5. The longer the food chain from plants to fish, the lower the production obtained. Food web – interlocking food chain - no 100% energy transfer - approximately 90% is lost per transfer Principles of Aquaculture 6. A unit of water can only produce and maintain a certain weight (carrying capacity) of species of fish depending on certain factors and their interaction Carrying capacity Factors Affecting carrying capacity: – maximum biomass Water quality that a body of water can Size of fish support. Quantity and quality of ration Biomass Feeding habit of the fish – total weight contained Quantity and quality of fertilizer in the sample Species of fish Ways to increase carrying capacity: Fertilizer application Feeds Water management Stock manipulation Integrated farming Principles of Aquaculture 7. The fertility of a unit of water and its ability to produce natural food organisms can be increased by adding organic or inorganic fertilizer to the water. Nitrogen and Phosphorus Increasing the availability of food Most important in primary through addition of fertilizer. production Excess in nitrogen have NPK – 3 basic nutrients detrimental effect Types of Fertilizer: o pollution Excess in P- no known Organic – animal manure and plant waste detrimental effect materials o Limiting nutrient Inorganic – has inorganic nutrients supplying Nutrient cycling one or more of the three needed nutrients. Involves a number of chemical Complete : 14 – 14 – 14 and biological processes Two : 16 – 20 - 0 (Ammonium phosphate) Single : 46 - 0 – 0 (Urea) Bacteria is the major contributor Principles of Aquaculture 8. When the biomass of fish in a pond is utilizing fully the natural food organisms present and the carrying capacity has been reached, an increase in the carrying capacity can be obtained by providing supplemental feed. Supplemental feed – can increase the carrying capacity of the water * Overfeeding should be avoided 9. When a ration is supplied as a pond supplement, its quality must be upgraded by natural fish food organisms eaten by the fish. Principles of Aquaculture 10. When natural fish food organisms are reduced due to cropping by fish and are no longer supplementing the ration, a complete ration containing essential nutrients must be provided to gain an increase in carrying capacity. 11. The maximum biomass of fish that can be produced in a unit of water depends on the quality and quantity of the ration that can be put into the pond without causing the dissolved oxygen to reach levels stressful or fatal to the fish. Principles of Aquaculture 12. The quantity of ration that can be fed per unit area per day is limited by the efficiency of the ecological system in waste disposal and re-oxygenation. * Dissolved oxygen (DO) should be maintained at optimum levels 13. When dissolved oxygen reaches limiting levels in fed, standing water ponds, aeration and/or bio-filters can be used to raise O2 levels, increase feeding rates and carrying capacity. Principles of Aquaculture Types of Aerators Mechanical aeration – emergency aeration a. Paddlewheel aerators - circulates and splashes water into the air; - generally considered the most effective b. Floating sprayer types - pumps water from below the surface and spray it into the air c. Air blowers - injects air either at one point in the ponds or through a perforated pipe d. Venturi aerators - sucks air into a pipe through which the low DO water is pumped paddlewheel air blower air from compressor Principles of Aquaculture Types of Aerators Flushing of high DO water into low DO pond water is effective and inexpensive, provided an adequate supply of high DO water is available. Sources of such water include nearby streams, wells, ponds or coastal waters. Flushing by gravity flow is the least expensive, but not often available. Principles of Aquaculture Filtration system: Filtration – aims to remove suspended and dissolved materials/impurities from the water. DIFFERENT CATEGORIES/ CLASSIFICATION OF FILTERS A. Mechanical Filters * Effluent-sludge system B. Biological Filters * Clam and seaweed filter C. Biochemical Filters * STAGE I: Aerobic stage * STAGE II: Anaerobic stage D. Chemical filters * ozone * activated carbon * ion exchange filters Principles of Aquaculture Filtration System: A. Mechanical Filters * Effluent-sludge system - equipped with a series of four hydrotech drum-shaped rotary sieves designed to remove the effluent from the main outflow - uses small sizes of mesh screens (example 90 micrometers) - removes suspended solids and organic substances B. Biological Filters * Clam and seaweed filter - involves letting the effluent flow into sedimentation pond and the water is circulated through a bed of bivalves which filter out phytoplankton. The water is then sent to a bed of green or red seaweed that absorbs dissolved nutrients. Principles of Aquaculture Filtration System: C. Biochemical Filters * STAGE I: Aerobic stage ❖ pond water is pumped into a trickling filter containing a specially developed material used to enhance growth of nitrifying bacteria. ❖ Here, the ammonia content of the water is oxidized to nitrate * STAGE II: Anaerobic stage - ❖ waste from pond bottom is collected in the sedimentation pit to produce volatile fatty acids. ❖ The acids together with the overlying water are pumped to fluidized bed reactor, a biofilm is created around grains of sand consisting of denitrifying material that uses the volatile fatty acids as an energy source to reduce nitrate to N2. ❖ Here too, the organic waste is transformed to CO2. ❖ The two gasses are released harmlessly into the atmosphere and clean water is returned to the ponds. Principles of Aquaculture Filtration System: D. Chemical filters * Ozone ❖ is a promising solution to water pollution in aquaculture. ❖ Organic wastes in the water is not removed by filtering or settling tanks, but ozonation effectively eliminates them by neutralization, oxidation and by killing bacteria in the circulating water. ❖ Although its use in aquaculture has been cautious due to its potential effect on fish, it has advantages over other disinfecting methods. ❖ Ozone reduces (BOD) and (COD) in water to almost zero. ❖ Effectively decreases the accumulation of non-biodegradable organic compounds in re-circulatory systems through foam fractionation. It helps in solid removal and granular filtration. ❖ Although ozone does not remove ammonia directly, it can precondition water for biofiltration by splitting large organic compounds into smaller biodegradable materials that are more easily removed by heterotrophic bio- filter bacteria. Principles of Aquaculture Filtration System: D. Chemical filters * Activated carbon ❖ this is a commonly used tool for the removal of organic molecules. ❖ When the water enters the filter filled with carbon, all the carbon’s pores are free to remove the solutes. ❖ At this point the solutes are largely taken up by the first layer of granules in the filter that the water passes through. ❖ But as the time goes on, the absorption site of those first carbon granules are filled, the granules deeper in the filter are relied upon to remove the dissolved materials. Principles of Aquaculture Filtration System: D. Chemical filters * Ion exchange filters ❖ when ion exchange resins are manufactured there are particular ions bound to the inert resins. ❖ As water with other ions passes through the filter, the ions in the water are captured by the resins which release the ions that were originally bound to it. ❖ For example, calcium can be taken out of the water if it replaces sodium on the resin. It will take two sodium ions from the resin to replace one calcium ion in the water. ❖ There are many kinds of resins available, depending on the type and charge of the ion that is needed to be removed. ❖ By far the most commonly used exchange resin in aquaculture is the zeolites, a cation exchange material; one of the zeolites, clinoptilolite, can be used to remove NH4+ from the water. Principles of Aquaculture 14. Carrying capacity per unit area can be further increased by exchanging water to reduce the concentration of organic matter, reducing BOD and increasing DO levels allowing higher rates of feeding. Maximum carrying capacity per unit area can be obtained in flow-through (raceway) systems. 15. For a given carrying capacity, the weight of fish can be composed of a large number of small fish or a smaller number of larger fish. However, a given unit of water can maintain more weight of small fish than large fish. Principles of Aquaculture 16. The lower the trophic level the fish fed on, the higher the biomass of fish a pond can carry. Top Carnivores 2nd Level Carnivores 1st Level Carnivores Herbivores Producers Principles of Aquaculture 17. In an environment that is not limited by wastes from feed and/or biota, the greatest biomass of fish that can be maintained in the pond can be produced by a combination of species differing in their feeding habit. Example : ❖ Milkfish + Crabs ❖ Milkfish + Prawns ❖ Milkfish + Grouper ❖ Milkfish + Crabs + Prawns ❖ Milkfish + Seabass ❖ Milkfish + Tilapia + Crabs 18. In an environment where growth is limited by wastes from feed and/or biota, the greatest biomass of fish that can be maintained in the pond is the monoculture of a fish that will continue to grow in water of poor quality. Principles of Aquaculture Aquaculture Management System A. Monoculture – stocking of 1 species of fish in the same pond 1. Mono-size stocking – stocking of 1 age or size of fish at a time 2. Multi-stage stocking – fish of uniform size are stocked in progressively larger pond. 3. Multi-stocking – stocking of different age-groups of fish 4. Mono-sex stocking – one sex only 5. Double cropping – 2 species in the same pond but in different seasons ex. Channel catfish – summer Rainbow trout – winter Nile tilapia – summer Blue tilapia - winter Principles of Aquaculture Aquaculture Management System B.Polyculture – Two or more non-competitive or compatible fishes ❖ Grass carp – roams in all strata of the pond feeding on higher aquatic plants ❖ Silver carp – mid-water dweller, feeds on planktons ❖ Big-head carp – mid-water dweller, feeds on zooplankton ❖ Black carp – bottom dweller, - carnivore; feed on mollusks ❖ Mud carp – bottom dwelling omnivore, - feeding on benthic animals and detritus. Factors Affecting the Selection of Species for Polyculture ❖ Compatibility of species ❖ Availability of natural food ❖ Suitability of environmental conditions ❖ Demand or price of the fish Principles of Aquaculture Aquaculture Management System C. Integrated Farming – Integrated fish farming is a system of producing fish in combination with other agricultural/livestock farming operations centered around the fish pond. * The farming sub-systems are linked to each other in such a way that the by- products/wastes from one sub-system become the valuable inputs to another sub-system * Ensures total utilization of land and water resources of the farm resulting in maximum and diversified farm output with minimum financial and labor costs. ❖ Rice – fish culture ❖ Rice – clam culture ❖ Rice – pig – fish culture ❖ Vegetable – duck – fish culture Principles of Aquaculture 19. Natural Fish food organisms normally supply all the essential nutrients of fish need to reach their maximum growth potential as long as the supply is not limited. When the standing crop of fish reaches a level where growth slows, maximum growth can be regained by feeding the fish a ration of sufficient quantity and quality. Standing Crop – biomass at a particular time. 20. Fish that are in poor health will not grow as rapidly as that are in excellent health Principles of Aquaculture 21. As cultured animal must grow to a minimal acceptable size, in a growing period, fish species with equal minimum marketable sizes may grow at different rates varying as much as 100% or more. Growth - any change in the size or amount of body material can be positive or negative, temporary or long lasting Growth in Fishes: Most of the fishes exhibit Indeterminate growth (growth is sustained throughout their lives if sufficient food is available; though the growth pattern will be diminishing). In contrast with determinate growth (definite size at any one age) * Growth stoppage in fish is not associated with sexual maturity. Fish may grow throughout their lives. Principles of Aquaculture Factors Affecting Rate of Growth 1. Population density – an increase in the population will correspond to a decrease in the growth rate. 2. Genetic variations - 3. Longevity – life span 4. Length of growing season/period 5. Water temperature – when water temperature exceeds the optimum range growth rate usually decreases - temperature affects abundance of food 6. Photoperiod – length of daytime - growth rate of fishes increases as the photoperiod is increased and decreases with a decrease in photoperiod Principles of Aquaculture Factors Affecting Rate of Growth 7. Water chemistry – chemistry of water is the basis for its fertility and production which is also related to growth. - good quality water encourages growth because it is not stressed 8. Dissolved oxygen level 9. Predator – prey relationship 10. Food * Amount * Quality * Attractability * Digestibility 11. Biotic factors – competition 12. Dominance and peck order (hierarchy) Principles of Aquaculture LENGTH AND WEIGHT MEASUREMENT Length and Width: 1. Total length – measured from the tip of the snout to the tip of the longest portion of the caudal fin 2. Standard length – measured from the tip of the snout to the caudal peduncle 3. Fork length – measured from the tip of the snout to the middle portion of a forked caudal fin 4. Body depth – width measured from the dorsal side to the ventral side in the deepest body portion of the fish Weight: 1. Total weight – weight of the fish when no part is removed 2. Bulk weight – biomass Principles of Aquaculture GROWTH PARAMETERS Absolute growth - the difference between the initial length or weight and the final length or weight of fish. - gain in weight/ length Absolute growth = Wf - Wo Absolute growth rate – gain in weight/length per unit time Absolute growth rate = Wf - Wo days of culture Relative growth – percent weight gain of fish in relation to its initial weight/length. Relative growth = Wf - Wo X 100 Wo Relative growth rate – percent weight gain of fish in relation to its initial weight/length. Relative growth rate = Wf - Wo X 100 Wo (days of culture) Principles of Aquaculture 22. The smaller the fish, the higher is its basic metabolic rate so that mare food per unit of body weight is needed for a small fish to reach and maintain maximum growth capacity than for a larger fish. 23. As the density of fish increases, the standing crop per unit of water increases and the amount of food available per fish decreases. When the amount of food per fish drops below optimum levels or DO drops below optimum levels due to high rates of feeding, the growth rate will continue to decline until growth stops. Principles of Aquaculture 24. For a given level of food abundance, when the critical standing crop is reached during the culture period, the higher the stocking density, the lower is the average weight of fish harvested. Critical standing crop – a situation wherein the is no weight gain and no weight loss occurring in the cultured fish 25. For short periods of time, density and final weight of fish can be regulated by the number of fish stocked. Principles of Aquaculture Different Levels of Culture Extensive - low stocking densities (1 to 3 fish/sq.m) - natural food only - may use fertilizers Semi-intensive - moderate stocking density (4 to 6 fish/sq.m) - natural food plus supplemental feeds; - greater water chance rate; - may use pumps Intensive - High stocking densities (6 fish and above/sq.m) - regular feeding; - pumps and mechanical aeration Principles of Aquaculture 26. For long culture periods, where reproduction is possible or where fish spawn at a very young age, the density and size of the fish can be controlled by biological means. Use of piscivorous fish Monosex culture Genetic manipulation Production of late spawners Sex reversal Sterilization 27. The use of carnivorous species to control fish density will increase average growth rate and percent of harvestable fish but will decrease the total yield. Total yield – all organisms to be harvested Net yield – organisms you desire to harvest Principles of Aquaculture 28. Maximum potential yield will be highest in water that has the highest carrying capacity per unit volume. 29. In mono-harvest system, net yield can never be greater than the carrying capacity of a unit of water in one culture period. 30. Higher yields per unit area can be obtained by stocking optimum numbers of various sized fingerlings, partial harvesting, then re-stocking with a number of small fingerlings equivalent to the number of fish harvested. Principles of Aquaculture 31. All aquaculture systems must be economical 32. Highest yields per unit area are not the most economic in ponds receiving ration and/or fertilization. Highest economic profits are below the point of maximum yields.