Milkfish Culture 2024 PDF

A Lecture on Brackishwater Culture Prof. Ronald P. Sombero College of Fisheries Mindanao State University General Santos City July 20, 2024  Milkfish Culture -In the Philippines, milkfish culture from fingerling to marketable size in bracki...

A Lecture on Brackishwater Culture Prof. Ronald P. Sombero College of Fisheries Mindanao State University General Santos City July 20, 2024  Milkfish Culture -In the Philippines, milkfish culture from fingerling to marketable size in brackishwater ponds generally requires the propagation and maintenance of abundant natural food, the lablab - compared to lumut (filamentous green algae) or plankton, lab-lab is better in supporting growth though it needs a relatively longer period of propagation -lab-lab uses more material input and supervision, and is more susceptible to deterioration during prolonged adverse conditions. -Lab-lab can be easily depleted by overgrazing of milkfish  About Milkfish… Comprise the bulk of aquaculture production in the Philippines They are hardy and fast growing, and can be raised in fresh-and brackishwater ponds and pens. One of the cheapest source of protein, thus, it is acceptable to all socio-economic strata in the country  About Milkfish… Filter feeders. They have no teeth but have fine gill rakers that concenrate microplankton. Benthic feeders. They nibble or browse on adhering or even floating lab-lab, periphyton or lumut. Daytime feeders. They feed less at night. Euryhaline. They can withstand extreme but gradual salinity fluctuation (0 to 100 ppt) but grow faster in natural waters of 0-40 ppt Phytophagous. They eat plant materials, and can easily digest plants owing to their long intestines. But can also adjust to artificial feeds-rice bran, trash fish, fish pellets-and hence, also considered omnivorous.  About Milkfish Resistant to diseases and not cannibalistic. They do not prey on each other and are not easily affected by infectious diseases, hence, they can be grown in relatively higher densities. Exhibit compensatory growth. Milkfish growth may be stunted under adverse conditions, but they can grow fast (exponentially) when conditions become favorable again.  Pond Culture Pond Preparation Stocking/Stock Management Feeding/Feed Management Water Quality Management Harvesting  Pond Preparation The objective is to grow lab-lab The amount of lab-lab grown in the pond is dependent on the manner of pond preparation Lab-lab is grown chiefly by a combination of organic and inorganic fertilizers Preparation of pond for lab-lab starts one or two months before stocking the fingerlings In order to obtain best growth, eradication of unwanted species and maintenance of good water quality is necessary  Basic Procedures 1. Drain the pond completely and allow to dry for about 1 to 2 weeks until soil cracks. Prolonged drying is not advisable as it makes the soil hard and powdery. 2. Eradicate unwanted species by using organic pesticides such as tobacco dust, derris root and/or combination of fertilizer and lime. When using tobacco dust, spread over moist bottom 300 to 400 kilograms per hectare, and allow to stand for a week. The application of a combination of hydrated lime and ammonium sulfate fertilizer (21-0-0) is done by broadcasting lime-ammonium mixture at a ratio of 5:1 on wet areas of the pond bottom during a sunny day. Reaction of lime and fertilizer releases heat and ammonia which effectively kills unwanted species in the pond. Pond Bottom Drying Organic Fertilizers Phosphate Fertilizer Nitrogen Fertilizers Ammonium nitrate Urea Application of hydrated lime ammonium Fertilizer application using sulfate to eradicate inorganic fertilizer by broadcasting unwanted species to bolster growth of lablab. 3 Commonly used forms of Lime Unslaked lime (CaO or quicklime)- calcium oxide.  Unslaked lime (quick lime) It is manufactured by heating crushed limestone or seashells. It is the fastest form. It has an efficiency rating of 173% of CaCO3. It is known to control water and soil acidity. Also to control pond pests and diseases.  Slaked Lime Slaked lime (Ca(OH)2 or Hydrated lime)-It is sometimes sold as dolomite. Hydrated lime is calcium hydroxide.  Slaked lime (Hydrated lime ) Also known as burnt lime It has an efficiency rating of 135% CaCO3. It is also a fast acting form. It is use to kill surviving animals and to control acidity. Agriculture lime (CaCO3 or dolomitic lime) Agriculture lime( Dolomitic lime ) Agricultural lime is pulverized calcium carbonate the same material that makes up coral reefs. It is sometimes sold as dolomite. Crushed limestone or seashells. It has an efficiency rating of less than 100%. This material is slow acting but due to its relatively low cost and ease of application it is the best for long term control of acidity. Agriculture lime is recommended for aquaculture use. Pond Liming  Basic Procedure 3.Apply chicken manure at 2 tons per hectare. Flood to a depth barely covering the pond bottom, then apply 15 kg per ha of urea or 45-0-0 two to three days later to speed up the decomposition of chicken manure. Method of application is by broadcasting.  Basic Procedure 4. Increase depth gradually over a period of one to one-and-a-half months, adding 3 to 5 centimeters to the water level each time until the stocking depth of 30 to 40 cm is reached. An abrupt increase in depth causes lab-lab to detach and float. Install fine mesh screens at the gates to prevent re-entry of wild species. 5. Subsequent application of 16-20-0 at 50 kg per ha or 18-46-0 at 20 kg per ha may be made at 1 to 2 weeks interval to bolster growth lab-lab.  Stocking in NP or TP Stocking of fry in the pond is done in the early morning or late afternoon when the temperature is cool to prevent temperature shock The newly arrived fry are normally contained in double-lined oxygenated plastic bags with salinity ranging from 15 to 25 ppt. The fry are usually emptied into plastic basin to sort out predators. If salinity of the water in the transport bag and that of the NP are approximately the same, the fry may be stocked directly into the NP Stocking the nursery or transition ponds  Stocking in NP or TP Stocking rate is from 30 – 50 fry per m2 If the salinity difference is over 5 ppt, acclimation should be done to prevent salinity shock during transfer, especially if the fry is moved from a lower to a higher salinity To acclimate, gradually add pond water inside transport bags until salinity is equalized After 30 – 45 days, the fry grow to fingerling size (3-5 g) with average survival of 60-70% survival Newly-grown fingerlings may be stocked right away in the RPs Fingerlings may be held temporarily for 6 months to one year in TP or SP at the density of 10 – 15 fingerlings per m2. In the TP, the fingerlings subsist on natural food like lab-lab, lumut or plankton with or without supplemental feeds.  Stocking in the RP Stocking is done early morning or late in the afternoon Fingerlings are caught from the NP or TPs and held in a fingerling seine The seine may be placed in a canal where it is carried slowly and closely to the pond where the fish are to be stocked If this is not possible, place a few hundreds of fingerlings at a time in plastic bags and carry them to the pond For longer distances, oxygenated plastic bags will be necessary to ensure good survival of fingerlings It is best to count the fingerlings to prevent under or overstocking  Stocking in the RP The fingerling seine should be positioned near the mouth of the gate where flowing water can sustain the fish that are crowded in the seine Release fingerlings at the mouth of the gate where the water is normally deep. Do this slowly to prevent environmental shock. In the modular pond system, a stocking density of 3000 fingerlings per ha is based on the area of the last module This means that in a 1:2:4 pond ratio, the last module being 4 has will be multiplied by 3000 to come up with 12,000 fingerlings The fingerlings will be stocked in the first in the first module having a 1 ha area If the set of module is irregular, say 1:3:5 ratio, the rule is to add the pond hectarage (1+3+5) which equivalent to 9 has and is multiplied by a factor (1,714), giving a total of 15,426 fingerlings to be stocked in the first module.  Care of Stock The main concern after stocking is the maintenance of optimum water condition for both the fish and natural food When using lab-lab as the food base, it is necessary to apply fertilizer (16-20-0) at 50 kg/ha every 12 to 15 days to maintain good growth of natural food. If the tide allows, replenish about 1/3 of the pond water before every fertilization. In hot months, more frequent flooding is needed to compensate for compensation Depth is kept at about 40 cm, at most 50 cm  Care of Stock During rainy months, it is necessary to drain the uppermost freshwater layer in the water column to prevent sudden drop in salinity Towards the end of culture period, lab-lab may be prematurely depleted because of overgrazing, poor water conditions or persistent inclement weather. Supplemental feeds may be given at a daily rate of about 5% of the estimated total biomass of the fish, using artificial feeds like rice bran or bread crumbs.  Care of Stock Abnormal occurrences such as the fish appearing to be gasping at the surface or swimming in circles may be at times experienced Indicators of stress associated especially with insufficient dissolved oxygen Water should be replenished at the first opportunity. In extreme cases, mass kills can occur especially in the morning of a very calm and windless day If replenishing water is not possible, water from an adjoining pond may be made to flow so that water is agitated. Pumps may also be used in such an emergency  Care of Stock Sudden rain or thunderstorm during a hot day may also present dangers Sudden change in water temperature may result to fish kills. Adverse weather conditions should be anticipated. Extra precautions should be observed to minimize possibility of dike wash-out, flooding and the like.  Harvest and Post-Harvest Pasulang method is employed during harvest Pasulang means to “swim against the current” The fish are gathered in the catching pond or canal system during spring tide, and drag seines are used to collect them They are scooped into chilling tanks or boxes where the temperature is low enough to kill them In the chilling tank or box, a 1:1 ratio of ice to a kilogram of fish is enough to lower the temperature of the fish to about 4oC in two hours.  Harvest and Post-Harvest The remaining fish in the totally drained pond are collected by hand Milkfish are sorted according to quality (size, freshness) and then packed into wooden boxes (kahon), metal tubs (banera, or bamboo baskets (kaing) ready for retailers and fish brokers. Harvested bangus may be sold fresh, dried, smoked, deboned, pickled or sent to cannery for processing or packed in cans like sardines. Harvesting  Extensive Culture System Use low stocking densities. No supplemental feeding. Water change is affected through tidal means. Ponds are stocked at 1,000 to 3,000 juveniles/ ha. Production range from 0.5 to 1 ton/ha/cycle.  Modified Extensive Culture Modified Straight Run System The fish depend on natural food for the first three months and the last month of grow out are provided with supplementary feed when natural food become limiting. Allow the production of 1 ton/ha/cycle.  Modified Extensive Culture Modular Comprise three stages of rearing. As the fish grow, they are move from a smaller ponds to a larger ponds. Three ponds with areas increasing at a ratio of 1:2:4 or 1:3:9 form a module. The culture period in each pond last for 30 days, and once vacated, the pond is immediately prepared to receive the incoming stock. The continuous program of pond preparation, stocking, transfer, and harvest possible to have 6 to 8 cycle/year. Allowing the production of 2 tons/ha/cycle.  Semi-intensive system Semi-intensive system are adapted to increase yield over the traditional, extensive system, but with lower energy requirement compared to intensive sytem. Fish are stocked at 8,000 to 12,000/ha The nutrient requirement of the stock is supplied by both natural food and supplemental feed. Fish are dependent on natural food for the 1st month of culture when biomass is about 300-400 kg/ha. Supplemental feed is provided from the second month onwards. Production system range from 1.5 to 3.5 tons/ha/cycle  Intensive Culture System involves deepening of ponds and stocking at very high density (>20 000 fish/ha). Aeration, pumping, and feeding are employed to support high fish biomass and production levels in excess of 4 tons/ha/cycle are achieved. Can be practiced in marine pens and cages. The stocking density in fish pens is 5–20 fish/m2 For floating, stationary cages, stocking density is maintained at 10–30 fish/ m3  Other Alternative Methods of Culture Modular or Progression Stock Manipulation Deepwater Culture Polyculture Crop rotation Bait fish culture  Modular Method A continuous program of pond preparation, stocking, transfer and harvest basically characterize this technique It allows 6 to 8 croppings per year with a yield or production range of of 2-4 tons/ha/yr The lay-out of its grow out pond forms a module at a ratio of 1:2:4 or 1:3:9 with its nursery and transition pond representing 10 and 6%, respectively of the production area. FIGURE 1 Lay-out of milkfish farm using progression or modular system  Modular Milkfish fingerlings are reared in three production stages for 30-45 days each Movement of the fish were from a smaller to a bigger pond compartment Immediately upon transfer or harvest of stock in each compartment, it is prepared to receive a new stock Density or rate of fish stocked in the 3 stage module decreases towards the last production compartment with 3000 fish/ha rate  Modular For instance, under a 1:2:4 module, the first compartment is stocked initially with 12,000 fingerlings, decreased to 6,000 fish/ha in the next compartment and 3,000 fish/ha in the last. The NP and TPs are stocked with the whole year fry requirement of the rearing or production pond with an allowance for mortality Preparation of the pond compartment is done within 30-45 days Natural food grown in the compartment is primarily lab-lab  Modular Water level is maintained at 30 cm depth and changed every high tide A f te r 3 0 - 4 5 d a y s r e a r i n g i n t h e l a s t compartment, milkfish of about 200-250 g are harvested either by current method (pasulang) or total drainage.  Modified Modular Technique This technique is a two stage production system wherein the grow-out ponds (formation and rearing pond) have a ratio of 1:2 It allows 4 croppings per year with 2-4 tons kg/ha production The first crop is group in the formation and rearing ponds for 85 days while the rest of the crops were grown for 70 days Preparation of the pond and growing of natural food is done every 35-45 days The nursery pond is initially utilized to grow milkfish fry to fingerling and eventually as a transition pond 2 alternately with transition pond 1 once natural food is overgrazed or after 35-45 days. Milkfish of 200-250 g is harvested using the current method or total drainage.  Stock Manipulation This is a method of managing fish population by proper stocking and harvesting with the aim of maintaining a balance between the fish population and food supply This technique was developed and popularly practiced in Taiwan Pond area of 3-8 ha are stocked 3-4 times with multi- sized overwintered and newly caught milkfish The practiced stocking pattern is 4000-5000/ha fingerlings of 5-100 g in April, 5000-8000/ha fry from May to August Harvest of 200-300 g fish starts in August until November with each fish group cultured for 150-180 days  Stock Manipulation Under this technique, the fish biomass was initially stocked at about 100 kg/ha and after two months the biomass reaches 700-800 kg/ha which is the pond carrying capacity in Taiwan Partial harvest of stock at this time reduces the biomass to 250 g/ha and thereafter the biomass fluctuates between 250 kg/ha and 750 kg/ha until harvest With this multiple stocking and size scheme, a yield 0f 2-3 tons per hectare per yr is possible The fish are harvested using a gill net A 3 month period of pond preparation is done to encourage an abundant growth of benthic algae  Stock Manipulation Pond preparation includes draining and drying, broadcasting of 500-1000 kg/ha chicken manure or 300-500 kg/ha rice bran, repeated admission of 10-15 cm water, eradication of pest and predator using 200 kg/ha tea seed or tobacco waste and application of 3-100 kg /ha of sodium silicate. A 1-3 mm thickness of algal bed is expected to develop Water in the pond is maintained at 15-50 cm depth and changed every high tide throughout culture Supplemental feeds like rice bran (30-50 kg/ha) or soybean or peanut cake (20-30 kg/ha) is given daily or once every two days to avoid overgrazing of natural food  Modified Stock Manipulation A modified stock manipulation technique was tested in the Philippines It employed a 3 time stocking at 5 size groups (half-grown, post fingerling, and first to third fingerling; size range of 0.6 g to 130 g) at 1,500-3,000/ha Harvest of 200-250 g size fish was carried out 45 days after initial stocking and every 15 days thereafter A 2.5 to 3.5 ton/ha/yr production in 3-4 crops can be attained Water depth in this ponds were however maintained only at 20 cm Supplementary feeding of rice bran at 2% of total fish biomass was given only when overgrazing of natural food occurs Extensive Deep Water Culture Technique This is characterize by the rearing of fish at higher density, in deeper waters and plankton a food With deeper water, bigger water volume and more space is provided to fish and high natural food biomass can be propagated Milkfish fingerlings at 4,000-6,000/ha are stocked in ponds with a depth of 70-120 cm Extensive Deep Water Culture Technique Plankton are cultivated using inorganic fertilizer (22 kg/ha 18-46-0 and 25 kg/ha 15-20-0) broadcasted over the pond or placed in a platform submerged 15-30 cm from water surface Growth of plankton is maintained at 20-30 cm transparency by bi-weekly dressing of inorganic fertilizer This technique allows a milkfish production of less than 3.6 tons/ha/yr in 3-4 croppings  Polyculture Technique Polyculture is combining two or more culturable species in one enclosure without necessarily sacrificing the requirements of each species. Postlarvae of shrimp (P. monodon or P. indicus) are stocked at 500-1000/ha with milkfish as a primary crop at 1000-3000/ ha This combination yields an addition of 100-200 kg/ha/crop Ponds used for this technique requires a 1-2 m wide and 0.75 m deep peripheral trenches and 1 m long twigs installed inside the trench to serve as shelter of shrimp during molting  Polyculture Technique Water level is maintained at 1 m depth through out culture Stocking of shrimp is done ahead of milkfish at the time natural food are grown Supplemental feed of trash fish is given occasionally particularly towards the end of the rearing period When milkfish was grown as secondary crop, it is stocked at 2,000/ha together with shrimp at 8000/ ha. This combination yield about 521.3 kg/ha/crop biomass  Polyculture Technique As the culture of shrimp becomes intensive, a 1:25 milkfish to shrimp combination was tried, and milkfish was found to attain better growth Milkfish can also be cultured together with crabs (S. serrata) A combination of 2,500/ha milkfish and 5000/ha crab can attain good survival and high total biomass Other species that can be possibly cultured with milkfish are seabass, tilapia, mullet and siganids.  Crop Rotation A simple method of alternately rearing two species of fish In the case of milkfish, it can be reared alternately with shrimp, particularly in intensive shrimp ponds. This technique allows the efficient utilization of the high natural food biomass and reduction of the organic matter level of the intensive shrimp ponds  Live Bait Milkfish Culture This method has for its purpose the rearing of milkfish as bait for tuna longline, dolphin fishing and other fishing activities Taiwan and countries in the South Pacific have been rearing milkfish as live bait for several years Milkfish’s hardiness during transport, its body shape and silver color, its schooling behavior, its good response to predator and its 90% bait well survival makes it an excellent baitfish 60 – 100 g size milkfish are used as bait The culture management in rearing milkfish as baitfish is similar to that of foodfish  Live Bait Milkfish Culture Traditional or shallow ponds are stocked with 4-6 cm milkfish fingerlings at 20,000-30,000/ha for 40 days While ponds of 100 cm depth are stocked with 50,000 fingerlings/ha In the Philippines, live baitfish culture of milkfish is recently practiced in Davao areas Milkfish of 70 g minimum size are sold at P6-7/pc. While frozen milkfish baitfish are exported to Taiwan at P3-7/pc. End of Slide Thank You!