Quarter 4 Module 6. Fishpens and Fish Cages
The design of fish cages and fishpens is determined by the behavior of the culture species. There is some confusion concerning the terms ‘cage culture’ and ‘pen culture’ in fish farming. Both cage and pen culture are types of enclosure culture, and involve holding organisms captive within an enclosed space while maintaining a free exchange of water. The two methods, however, are distinct from one another. A floating cage is totally enclosed on all but the top side by mesh netting, whereas pen bottom is formed by the lake or sea bottom. Cage and pen culture has become popular. For producing cheap fish protein as a business enterprise. Content Standards 1. The
learner
Performance Standards
demonstrates 1. The learner independently draws
understanding of the underlying
the layout plan of fishpen and fish
concepts in drawing the layout
cages.
plan of a fishpen and a
fish
cage. 2. The
2. learner
The
learner
independently
demonstrates evaluates
understanding of the underlying
a suitable site for fishpen and fish
concepts in evaluating a suitable
cages.
site for fishpen and fish cage. 3. The
learner
demonstrates 3. The learner independently
understanding of the underlying
understands how to construct
concepts in constructing fishpen
fishpen and fish cages.
and fish cages.
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Quarter 4 Lesson 1. Draw the Layout of Fish Pen and Fish Cage
Introduction Fish pens are fenced, netted structures fixed to the bottom substrate and allows free water exchange. On the other hand, fish cages are rearing facilities closed at the bottom as well as on the sides by wood cover, mesh or net screens. The design of fishpens and fish cages is determined by the characteristics of the species to be cultured. The lesson deals with drawing a layout of fishpen and fish cage and types of fish cages.
Specific Objectives At the end of the lesson, you are expected to: 1. determine the area and depth of fish pen and fish cage conforming to the site selected. 2. determine the materials for frame and types of net to be used based on the site selected and species to be cultured. 3. estimate the materials and cost. 4. determine the mesh size of net base on available fingerlings size and species of fish in the area. 5. identify other farm facilities needed for the laying out of fish pen and fish cages.
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Quarter 4 Pre-Assessment Directions. Choose the letter of your answer. Write your answer in your test notebook. 1. In order to make the fish cage float on the water, the cage must be equipped with ___________. a. framework b. netting system c. mooring system d. floatation system 2. As a general rule, what is the length of the mooring lines? a. two times of the depth of water b. three time of the length of the cage c. three times of the depth of the water d. two meters allowance during high tide 3. Which of the following keeps the whole cage in place at a certain location? a. barrier b. floater c. mooring d. framework 4. What factor usually determines the depth of fish cages? a. the mooring system b. capability of the owner c. natural productivity of the water d. the species of fish to be cultivated
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Quarter 4 5. What is the smallest unit of a net? a. mesh b. knots c. twine d. mesh size 6. What type of net cage fabrication refers to a ¼ m2 mesh? a. B-net b. CC-net c. DD-net d. knotless net 7. What aquaculture facility is usually supported by a fixed rigid framework of bamboo poles, palm tree poles and wood poles? a. hapa b. fish pen c. fixed fish cage d. floating fish cage 8. What part of the cage serves as walkways for working, feeding and monitoring? a. nets b. frames c. floaters d. mooring 9. Which of the following aquaculture facility is most suitable in a relatively large bodies of water? a. fish pen b. fishpond c. fixed fish cage d. floating fish cage
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Quarter 4 10. In general, which aquaculture facility has the biggest area? a. fish pen b. fish tank c. fixed fish cage d. floating fish cage
Design of Fish Cages and Fish Pens Before making the layout of the cage/pen, the size, depth and shape must be considered which is dependent mainly on the ability of the owner to design and construct as far as operation and maintenance is concerned. The biology and behavior of the fish species and the characteristics of the project site should be considered as well. The design must be simple but durable, easy to construct and economical. In Laguna Lake, the size of pens ranges from less than one hectare to more than 100 hectares. The shape of the enclosure is influenced by the characteristics of the cultured fish. For milkfish and tilapia, square and rectangular pens are commonly used. Circular enclosures are recommended for big head carp. Generally, the most economical shape of the pen is one that has the least perimeter. Circular shape require the least materials per unit area but relatively hard to construct. Generally, fish pens are most suitable in relatively large bodies of water and along coastal areas where the water level ranges only from 2.0 meters to a maximum of 7.0 meters.
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Quarter 4 On the other hand, the depth of the cage is usually determined by the production of natural food in water. Since natural food production is relatively higher on the surface, sunlight penetration is usually employed as the basis for depth. Types of Cages A. Fixed cage. It is essentially a net bag supported by posts which are anchored to the bottom of a river or lake. Although they are inexpensive, their use is limited to shallow, protected water with soft substrates.
Figure 1. Fixed cage
B. Floating cage. These are made from netting supported by a buoyant collar or a stable frame. This is the most widely used method of cage aquaculture because the cages can be made any size or shape.
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Quarter 4
Figure 2. Side view of a floating cage
C. Submersible. These cages are built with a rigid frame and because they are submersible, they can be moved up and down in the water column. If the weather is rough, the cage is lowered to deeper calmer water, but in calm conditions the cage remains near the surface.
Figure 3. Submersible fish cage
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Quarter 4 D. Submerged . These cages are the least common and are permanently installed under the water. They consist of a frame with slats for openings and are anchored to the substrate.
Figure 4. Submerged fish cage
Figure 5. Simple fixed cage
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Quarter 4
Figure 6.
Fixed cage for prawn
Fish pens in the Lingayen Gulf are made up of nets on all sides and utilize the sea bed as the bottom enclosure or often are provided with extended bottom nettings. A pen is usually supported by fixed rigid frameworks of coconut posts or bamboo poles and wooden frames, making it a stationary farming structure. Mariculture using fish pens is concentrated in the coastal and inland waters of Bolinao, Dagupan and Binmaley in Pangasinan and Aringay in La Union. The number of fishpens in these municipalities in 1996 amounted to 685 units spread across an area of 41.1 hectares. The surface enclosed by fish pens varies from one-fourth of a hectare to 2 hectares or more (BFAR,2001).
Figure 7. Fish pens in Lingayen Gulf (Photo: BFAR/N.A.Lopez, 2003) 175
Quarter 4 The most common species cultured is milkfish (Chanos chanos). At present, fishpen operators need to extend their culture period from 5 to 6 months to produce milkfish of marketable size (200-250 g/piece). In previous years, three months were sufficient to produce marketable sized fish. Harvest frequency has been reduced from 4 to 3 or 2 cycles per year. The major reason is the deterioration of water quality caused by low water exchange resulting from high fish stocking densities, excessive feeding and the unregulated establishment of these structures in municipalities.
Figure 8. Typical fishpen
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the coastal
Quarter 4
Assumption: A 200 m2 fishpen with a 1.5 to 2 meters depth can accommodate 3000 pieces of milkfish fingerlings. Compute for the number of milkfish fingerlings that can be accommodated with the following given area: 1. 2. 3. 4. 5. 6. 7. 8. 9.
350 m2 = 500 m2 = 650 m2 = 800 m2 = 1000 m2 = 1500 m2 = 2000 m2 = 2500 m2 = 3500 m2 =
_________
10.
5000 m2
_________
=
pieces pieces _________ pieces _________ pieces _________ pieces _________ pieces _________ pieces _________ pieces _________ pieces _________
pieces
Answer the given questions below. 1.
Differentiate the four types of cage.
2.
What is the difference/s between fish cage and fishpen?
3. If you are going to have an aquaculture project, which will you prefer? A fish cage or a fish pen? Why?
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Quarter 4
Design your own fish cage and fishpen. Follow the procedures below. a. Make a layout for fish cage and fishpen. Use half cartolina, pencil, ruler and coloring pens/crayola or any other coloring material. b. Label the different parts of fishpen and fish cage like floating systems, mooring systems, etc. c. Indicate also the measurements/scale used in the illustration.
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Quarter 4 Post-Assessment Directions: Multiple Choice: Read and understand each item below. Encircle the letter of the best answer. 1. In order to make the fish cage floats on the water, the cage must be equipped with ___________. a. framework b. netting system c. mooring system d. floatation system 2. As a general rule, what is the length of the mooring lines? a. two times of the depth of water b. three time of the length of the cage c. three times of the depth of the water d. two meters allowance during high tide 3. Which of the following keeps the whole cage in place at a certain location? a. barrier b. floater c. mooring d. framework 4. What factor usually determines the depth of fish cages? a. the mooring system b. capability of the owner c. natural productivity of the water d. the species of fish to be cultivated 5. What is the smallest unit of a net? a. mesh b. knots c. twine d. mesh size 179
Quarter 4 6. What type of net cage fabrication refers to a ¼ inch mesh? a. B-net b. CC-net c. DD-net d. knotless net 7. What aquaculture facility is usually supported by a fixed rigid framework of bamboo poles, palm tree poles and wood poles? a. hapa b. fish pen c. fixed fish cage d. floating fish cage 8. What part of the cage serves as the walkways for working, feeding and monitoring? a. nets b. frames c. floaters d. mooring 9. Which aquaculture facility is the most suitable in relatively large bodies of water? a. a fish pen b. a fishpond c. a fixed fish cage d. a floating fish cage 10.In general, which aquaculture facility has the biggest area? a. fish pen b. fish tank c. fixed fish cage d. floating fish cage
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Quarter 4 Glossary Anchor. Something that serves to hold an object firmly Biology. Life processes of an organism Buoyant. Ability of an object to float in water or air Intertidal. Of or relating to the area of the shore that is between the low tide and the high tide levels Mariculture. The cultivation of marine organisms in their natural environment Mesh. Material made from threads or wires with evenly spaced holes that allow air or water to pass through Penetration. Act of going through or into something Submersible. Able to be used underwater Substrate. Base on which an organism lives
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Quarter 4 Resources Republic of the Philippines, Department of Education. Public Technical Vocational High School Competency-based Learning Material. Third Year. Aquaculture NC II.
Dela Cruz, C. R. et. al. FAO Fisheries Technical Paper Republic of the Phillipines, Fishpen and Cage Culture Development Project in Laguna de Bay, Republic of the Phillipines, Freshwater Aquaculture Centre: Central Luzon State University, Muñoz, Nueva Ecija.
Toledo, C. 2009. AQUA203: Aquaculture Engineering. Lecture manual. Pangasinan State University, Binmaley Campus.
Merriam-webster.com
www.bar.gov.ph
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Quarter 4
Lesson 2 Evaluate Fishpen and Fish Cage Site
Introduction A suitable site for fishpen and fish cage is a very important factor for an aquaculture project to succeed. This lesson is about evaluating a suitable site for fish pens and fish cages. This includes ways of analyzing water current speed, natural food determination, in measuring water transparency and monitoring tide elevation. Specific Objectives At the end of the lesson, you are expected to: 1.
monitor the water current speed with a water current meter.
2.
measure water transparency with the Secchi disc.
3.
determine the tide level/flood water level of the area.
4.
be familiar plankton sampling and analysis of feeding requirement.
Pre-Assessment Multiple Choice: Choose the letter with the correct answer. Write this in your test notebook. 1. What do you call the animal components of planktons which are drifting with the water movement? a. detritus b. flagelletes c .Zooplanktons d.Phytoplanktons
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Quarter 4 2. Which of the following does not belong to the group? a. fish pen b. fish trap c. fish cage d. fish tank 3. It measures the magnitude and the direction of horizontal motion of the water a. Secchi disk b. Water sampler c. Eckman dredge d. Water current meter 4. Which of the examples below is configured for water column profiling and wave measurements? a. Refractometer b. Eckman dredge c. S4 current meter d. Astronomical regulator 5. How will you collect phytoplanktons? a. Towing a seine net b. Setting the barrier net c. Towing a plankton net d. installing collecting nets 6. Which is used in measuring water transparency? a. pH meter b. secchi disc c. thermometer d. dissolved oxygen meter
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Quarter 4 7. Which facility allows free flow of water while retaining confined fishes. a. fish cage b. fish tanks c. Fishpond d. fish sanctuaries 8. The following are the factors to consider in evaluating ideal site for fish pen except a. pollution b. accessibility c. water circulation d. altitude of the area 9. Which of the following is NOT a kind of natural food? a. lumut b. darak c. lablab d. plankton 10. It is the alternate rising and falling of the level of the sea. a. tide b. wave c. climate d. weather
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Quarter 4
Site Selection for Fishpen and Fish Cage
1. Water circulation. Water current circulation in an
area that provides
continuous flushing of water cages, makes dissolved oxygen highly available to fish and wash out metabolites. In the Philippines, northeast to southeast or vice versa prevails from March to August. 2. Protection from winds and waves. Locate a site protected from strong wind
action and water currents caused by a flood or heavy
runoff.Providing bamboo barricades or wave breakers facing the direction of the prevailing wind direction of the prevailing wind traps floating debris from damaging fish enclosures. 3. Dissolved oxygen concentration. The ideal range of dissolved oxygen concentration must be at least 3 ppm. 4. Temperature. The suggested temperature range is range is
20°C to
30°C. 5. Pollution. pH Level. To enhance a better growth, the recommended pH range is 6.8 to 8.0. 6.
Accessibility. The site must be accessible to land and water transportation to facilitate delivery of farm inputs and marketing of produce.
7. Other factors. One social problem existing in any fishery establishment is poaching. Poachers get into the project at night, bore hole on nettings to let the stock escape, then set gill net on surroundings of the project. This gives a bountiful catch overnight. Security in the premises fish cages may be enhanced by having good relation with local people in the vicinity. Another consideration is the source of fingerlings for periodic stocking.
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Quarter 4 Analyzing Water Current Speed The water current meter is used to measure the true magnitude and direction of horizontal current motion in any fresh or salt water and it can be configured for water column profiling and wave measurement. It is particularly useful in: 1. Wave zones where its vertical cosine response is needed. 2. Low current regimes where stability and resolution are needed. 3. High flow regimes where low drag and lack of moving parts permit practical deployment into concern for fragility. 4. For long deployment where memory capacity and programmability are needed. Sampling of Natural Food 1. General Information Suspended matter in the water column may consist of living organisms called plankton and may include loose particles referred to as detritus. Phytoplankton are plant components and zooplankton are animal components which “passively drift” in the water movements (Zeischel, 1970). 2. Ecological Importance Phytoplankton are the major producers in the aquatic world. Although small in size, they contribute an enormous quantity of the world’s supply of organic matter, serving as the basic food source of consumers like zooplankton and fishes.
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Quarter 4 3. Potential Phytoplankton play the following roles in larvae culture:
Provide nutrient to larvae.
Provide quality water medium by assimilating neutralizing inhibitory materials.
Improve the nutritional value of secondary food organism like zooplankton
Secrete metabolic products which may enhance larval growth and development.
4. Sampling Phytoplankton may be collected by towing a plankton net (180 meshes/sq. inch) through the water, a receiving container (usually a vial) is attached to one end of the net.
Figure 9. Plankton Net
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Quarter 4 Measuring the Water Transparency Using a Secchi Disc 1. Slowly lower the Secchi Disk into the water. 2. Stop when it disappears from sight. 3. Note at which point the line breaks the water surface. Mark this point A. 4. After noting at which point along the line the disk just disappears, lower it a little and then raise until it appears. Mark this point B. 5. Measure the transparency of the water as equal to the distance from
the top of the disk and count the knots along the line. This value is the Secchi disc transparency (in cm). How to measure Secchi Disc Visibility Depth
When the disc goes into the water, it will sink straight down and disappear from sight at some depth.
If the disc disappears at 30 cm depth, the cage contains enough natural food (mainly phytoplankton).
Secchi Disc Visibility depth of more than 30 cm is an indicator that there is not enough natural food and that the cage needs fertilization.
If Secchi Disc Vissibility depth is less than 10 cm, this means that
there
is
too
much
phytoplankton in the cage and there is a good chance of a dieoff that may lead to dissolved oxygen (DO) depletion.
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Figure 10. Measuring secchi disc visibility depth
Quarter 4 Some considerations when taking Secchi disc visibility test 1. clearness of the day 2. position of the sun 3. roughness of the water 4. sight of observer
Formula : Secchi Disc Vissibility Depth = {Depth1 + Depth 2} 2 where:
Depth 1 = depth at which disc just disappeared Depth 2 = depth at which disc just appeared
What is the role/importance of the following factors in site selection for fishpen and fish cage? a. Temperature b. Pollution c. Accessibility d. Dissolved oxygen concentration e. Protection from wind and wave action
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Quarter 4
Answer the questions briefly. 1. How important is the consideration of the project site for fishpen and fish cage? 2. How will you manage an aquaculture facility project of the source of the natural food for fish becomes low?
Read the instructions carefully and do the following: 1.
Provide your own Secchi disc for measuring transparency of the water.
2.
Measure at least six areas/locations in the water area in your school, if available.
3.
Compare the measurements gathered and write this in tabular form. The format is given below.
Disappearance
Reappearance
SDVD
(cm)
(cm)
(cm)
Station 1 2 3 4
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Quarter 4 Post-Assessment Multiple Choice: Choose the letter with the correct answer. Write this in your test notebook. 1. The animal components of plankton which passively drift in water. a. detritus b. flagelletes c .Zooplankton d.Phytoplankton 2. Which of the following does not belong to the group? a. fish pen b. fish trap c. fish cage d. fish tank 3. It measures the magnitude and the direction of horizontal motion of the water a. Secchi disk b. Water sampler c. Eckman dredge d. Water current meter 4. Which of the examples below is configured for water column profiling and wave measurements? a. Refractometer b. Eckman dredge c. S4 current meter d. Astronomical regulator
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Quarter 4 5. How will you collect phytoplankton? a. Towing a seine net b. Setting the varier net c. Towing a plankton net d. Installing collecting nets 6. How do you measure water transparency? a. pH meter b. secchi disc c. thermometer d. dissolved oxygen meter 7. Which structure allows free flow of water while retaining confined fishes? a. fish cage b. fish tanks c. Fishpond d. fish sanctuaries 8. The following are factors to consider in evaluating ideal site for fish pen except a. pollution b. accessibility c. water circulation d. altitude of the area 9. Which of the examples below is NOT a kind of natural food? a. lumut b. darak c. lablab d. plankton
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Quarter 4 10. What do you call the alternate rising and falling of the level of sea? a. tide b. wave c. climate d. weather
Glossary Assimilating. Take in (information, ideas, or culture) and understand fully. Augment. Make (something) greater by addition to; increase. Debris. Rubble, wreckage, ruins, litter and discarded garbage/refuse/trash, scattered remains of something destroyed. Enormous. Very large in size, quantity, or extent. Lethal. Harmful or destructive. Magnitude. Great size or extent Metabolites. A substance essential to the metabolism of a particular organism or to a particular metabolic process Natural foods. Minute plants or animals naturally growing in water. Phytoplankton. Minute plan organisms that drift with water currents Sand. A soil that has granular appearance Secchi Disc. An instrument used to measure water transparency Tide. The alternate rising and falling of the surface of the ocean Transparency. The condition of water whether opaque or transparent
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Quarter 4 Turbidity. The quality of the water being muddy, thick or opaque water due to suspended soil Vegetation. The kinds of plants covering a site
Resources Republic of the Philippines, Department of Education. Public Technical Vocational High School Competency-based Learning Material. Third Year. Aquaculture NC II.
Dela Cruz, C. R. et. al. FAO Fisheries Technical Paper Republic of the Phillipines, Fishpen and Cage Culture Development Project in Laguna de Bay, Republic of the Phillipines, Freshwater Aquaculture Centre: Central Luzon State University, Muñoz, Nueva Ecija.
Toledo, C. 2009. AQUA203: Aquaculture Engineering. Lecture manual. Pangasinan State University, Binmaley Campus.
Merriam-webster.com
www.bar.gov.ph
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Quarter 4
Lesson 3 Constructing Fish Pens and Fish Cages
Introduction A pen culture is similar to a cage culture because cages and pens allow water currents or wind action to carry away waste products and to continually provide oxygen. This lesson will provide you knowledge and skills on fish pen and fish cage construction. Specific Objectives At the end of the lesson, you are expected to; 1. prepare a list of construction materials; 2. position posts appropriately based on specifications; 3. select netting materials based on the size of fish stocked; 4. attach floats and sinkers properly; 5. inspect damaged net prior to installation; 6. set up nets to fit the frame; and 7. check proper placement of net’s bottom.
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Quarter 4 Pre-Assessment Directions: Multiple Choice. Choose the letter with the correct answer. Write this in your test notebook. 1. What part of a floating fish cage nets are suspended? a. floaters b. anchors c. frameworks d. mooring lines 2 Which is a disadvantage of culturing fish in a fish cage? a. more man power requirement b. better control of fish population c. easier handling, inventory, and harvesting fish d. efficient control of fish competitors and predators 3. What is the first step in net cage fabrication? a. double lace every mesh b. rig all sinkers to the rib lines c. make splices on the four corners d. cut net according to the desired specification 4. What is the mesh size of net used in grow–out cages? a. 15 mm b. 20 mm c. 25 mm d. 30 mm 5. Why should bamboo poles or anahaw logs used in fish pen construction be cleared of sharp edges? a. to prolong its life span b. to make staking easier c. to increase its buoyancy d. to prevent damage to the nets
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Quarter 4 6. What is the first step in fixing the net to the framework of a fish pen? a. Fix the net in place by driving bamboo pegs. b. Fasten double foot rope to the bamboo pole. c. Tie the head rope about 1.2 m above the water surface. d. Remove debris and other materials inside the enclosure 7. How do you align the poles to be installed between each of the guide poles? a. by using a rope b. by using of a transit c. by using a sighting device d. by using a bracing bamboo 8. What keeps the whole cage in a certain location in the water a. framework b. floating system c. mooring system d. netting assembly 9. Net fabrication will be based on the physical characteristics of the proposed site. This includes a. nature of water current b. characteristics of the cultured fish c. highest water levels or flood levels d. temperature and salinity of the water 10. The length of the nets needed is determined by multiplying the perimeter of the fish pen by a. 1.2 b. 1.3 c. 1.4 d. 1.5
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Quarter 4
Materials for Fish Pen and Fish Cage Construction A. Fish Pen 1. Framework/structure a. bamboo- most common b. wooden poles c. anahaw (palm tree) logs/coconut pole d. creosoted pole- pole treated with creosote (wood preservatives) e. steel/ G.I. pipe 2. Enclosure and barrier nets a. polyethylene nets b. polypropylene nets c. nylon nets d. woven bamboo splits
Fig. 11. Polyethylene net
Fig. 12 . Polypropylene net Fig. 13. Nylon net
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Quarter 4
3. Tying and braiding materials a. polyethylene rope and twine b. polypropylene rope c. nylon threads d. nylon cord (monofilament) e. rubber tire strips
Figure 15. Nylon Thread
Figure 14. Polypropylene Rope
Figure 16. Monofilament Nylon cord Figure 17. Rubber strips
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Quarter 4
Preparation of Frameworks 1. Bamboo poles and anahaw logs are cleaned of sharp edges to prevent net damage. 2. When bamboo poles are used for posting, the diaphragm is removed to reduce buoyancy.
Figure 18. Removing of Diaphragm of Bamboo Poles
Preparation of Net Installation Net fabrication should be based on the physical characteristics of the proposed site like depth of water and mud), highest water level or flood, and characteristics of species to be cultured. The perimeter of the fish pen must be known before the nets are cut and installed according to specifications.
Net Measurement The length of the net is determined by multiplying the total perimeter of the pen by 1.3. This is the ideal allowance for the net pen and cage. It gives equal stretching to the four sides of the mesh.
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Quarter 4
Example: Perimeter pen = 400 m. Therefore, the length of perimeter net required = 400 x 1.3 = 520 meters.
Procedure in Ribbing Nets (joining nets with rope) 1. First, enclose both ends of the nets. 2. Then, insert 5 mm polyrope at the first row of meshes of nets. 3. Weave with 210/18 resined nylon-twine one inch apart employing a clove hitch and knot. 4. Repeat the procedure for the succeeding layers until the desired depth of net is completed.
Figure 19. Ribbing Nets for Fish Pen 202
Figure 20. Barrier Net
Quarter 4 Net Assembly.
Assembly.
Barrier Net Installation The commonly used nets are 3 knots and 7 knots polypropylene nets. A 9 mm polyrope can be used for lower (foot) and upper (head) part of the barrier assembly. The installed nets can be adjusted according to fluctuations in water level.
Fixing Nets into Frameworks The installed nets are brought to the site and attached to the pen framework. Tie the head rope about 1-2 meters high above the water surface. Use the double footrope to fasten the bamboo pegs and stone sinkers. Install the net in place by driving the pegs and stone sinkers into the lakebed. After the net has been fixed in place, remove the debris and other materials inside the net enclosure as these may damage the nets.
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Quarter 4
Figure 21. Fixing Nets to Fish Pen Frameworks
B. Fish Cage 1. Framework/ structure a. b. c. d. e.
bamboo- most common wooden poles anahaw (palm tree) logs creosoted pole steel/ G.I. pipe
Figure22 . Materials framework
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Quarter 4 4. Enclosure and barrier nets a. b. c. d.
polyethylene nets polypropylene nets nylon nets woven bamboo splits
5. Tying and braiding a. polyethylene rope and twine b. polypropylene rope c. nylon threads d. nylon cord (monofilament) e. rubber tire strips 6. Floats a. b. c. d. e. f. g.
bamboo steel drum/ barrel Styrofoam plastic container aluminum cylinder PVC pipes rubber tires
Figure 23 . Commonly used materials as floaters. 7. Sinkers/anchors a. stone b. concrete slabs c. bamboo and wooden pegs Nets and Mesh Sizes Suitable for Fish Pens and Fish Cages Generally, the most suitable nets should be flexible or adaptable, for ease of handling; resistant to fouling growth and heat. The mesh size must be small enough to prevent the escape of fish and entry of predators. For hatchery operations of tilapia, the most common sizes of mesh used are 0.5 mm (hapa) for breeding, 10 mm for nursery and 20 mm for grow-out. However, as long as the fish cannot escape, larger 205
Quarter 4 meshes are recommended since they provide larger passageway for water circulation, slower rate of fouling, ease in handling and cheaper cost per unit area. Nets for Cage Fabrication
B- NET (1/4 in mesh) DD- NET (3/8 in mesh) CC-NET (1/2 in mesh)
There are many kinds of nets that could be used for fabrication. The most common are the B-net (1/4” mesh), DD-net (3/8” mesh), and CCnet (1/2” mesh). However, the most popular is the B-net because smaller fingerlings do not need a nursery cage. It is cheaper per unit area because it is wider (108 inches) than the other nets, hence, labor cost in fabricating cages is much lower, and tearing of one or two mesh do not easily provide an escape route for bigger fish. Floating System (Floating Fish Cage) The floats for floating cages must have the following qualities: a. high buoyancy b. fouling-resistant c. durable, enough to withstand the wind and waves For longer life and less fouling, floats used may be covered with protective materials such as rubberized canvass. Mooring System Mooring lines should be light and strong, flexible, highly resistant to wear, impact, abrasion, stretching and twisting. As a general guide, the length of the mooring lines should be three times the depth of water. Anchoring Device An ideal anchor must provide enough holding power with reasonable weight size. The type of anchor to use in the mooring system depends on the depth of water, nature of bottom, and water current. The three types of anchors are the following:
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Quarter 4 1. Dead weight anchors. They are recommended for mooring involving essentially vertical tension. A typical example is a concrete block.
Figure 24. Dead Weight Anchor 2. Embedment anchors. These are designed to dig into the bottom as they are being pulled by a horizontal force. It is recommended for sandy and muddy bottom.
Figure 25 . Embedment Anchor 3. Special anchors. These are the combinations of deadweight and embedment anchors. They are designed to resist vertical and horizontal components of tension.
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Quarter 4 Net Cage Fabrication The cage is made from netting materials, which are sewn together to form an oversized mosquito net. These are then installed in the modules in an inverted position. The dimensions of the cage will depend on the needs, capability, and production target of the fish farmer. For instance, a small cage measuring 5 x 10 x 2.5 m is easy to manage. One or two laborers can readily lift the cages during harvest or during routine inspection. Another advantage using smaller cages is that even if a cage gets damaged or destroyed, fish loss will be minimal. However, one can increase to as much as 10 x 25 x 2.5 meter to save on materials compared to fabricating several units of smaller cages. A 5 x 10 x 2.5 meter net cage would require at least one Role of polyethylene nets, a roll of polyethelene and 3-5 rolls of nylon twine. The 10 x 20 x 2.5 m net cage would use up to 2 ½ rolls of netting materials, 2 ½ rolls of polyethelene rope, and 8-10 rolls of nylon twine. Procedure in Installing Net Cage-to-Cage Frame 1. Hang the nets in bamboo raft-type frame. 2. Fix the synthetic ropes into the four corners of the frame. 3. Set the mooring system.
Bill of Materials and Cost Estimate for a 10m x 20m Floating Net Cage I.
Materials Materials
Quantity 54 pcs. 3 rolls
Unit Price (Php) 480.00 4, 500.00
4. GI Pipe 1.5” diam. X 6m # 40 5. PE net enclosure, size 17, knotted 200 mesh depth, 400 K/14 6. PE Rope # 14 (7 mm) 7. PE Rope #16 (8 mm) 8. PE Rope #24 (12 mm) 9. PE Twine #2 ( 1.0 mm) 10. Plastic Drum ( 200 L capacity) 11. Welding Electrode ( 1/8” diam.) 12. Paint Epoxy Primer 13. Stainless Steel bolt and Nut
25, 920.00 13, 500.00
2 rolls 3 rolls 1 roll 10 rolls 18 pcs. 30 kgs.
200.00 250.00 400.00 50.00 900.00 40.00
400.00 750.00 400.00 500.00 16, 200.00 1, 200.00
3L 120 pcs.
110.00 18.00
330.00 2, 160.00
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Cost (Php)
Quarter 4 with washer 14 mm diam. X 40 mm 14. Steel Plate (120 x 100 x 5 mm) 15. Paint brush ( 1”)
II. -
56 pcs.
20.83
2 pcs.
20.00 Total
1, 166.48 50.00 62, 566.48
Construction Cost Material Cost …………………………. P 62, 566.48 Labor Cost (22 % Material Cost) ………………… P 13, 138.96 Miscellaneous and Contingencies (10% Of Material Cost……………………… P 6, 256.64__ Grand Total P 81, 962.00 say P 82, 000.00
Directions. Go to your nearest hardware/agricultural supply stores in your locality. Canvass the prevailing price of the materials listed below. Follow the suggested format and provide at least three (3) price quotations from different stores/bidders. NO. 1. 2.
3. 4. 5. 6. 7. 8. 9.
Materials GI Pipe 1.5” diam. X 6m ach. 40 PE net enclosure, size 17, knotted 200 mesh depth, 400 K/14 PE Rope # 14 (7 mm) PE Rope #16 (8 mm) PE Rope #24 (12 mm) PE Twine #2 ( 1.0 mm) Plastic Drum ( 200 L capacity) Welding Electrode ( 1/8” diam.) Paint Epoxy Primer 209
Unit Price (Php)
Quarter 4 10. 11. 12.
1. 2.
Stainless Steel bolt and Nut with washer 14 mm diam. X 40 mm Steel Plate (120 x 100 x 5 mm) Paint brush ( 1”)
Is it possible to construct a fish cage at the mouth of a a river? Why? If your fish pen is located at the typhoon belt zone, what will you do to protect your structure?
Directions: Make a miniature/diorama of a floating fish cage. I. II.
Materials: Used net barbeque sticks Pop sickle sticks Glue and glue gun/glue sticks Cutter/pair of scissors styropor used rope How to Make a Diorama of a Fish Cage 1. Provide a layout of the fish cage. 2. Cut the barbecue sticks according to your layout. 3. Assemble the sticks into a frame.
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Quarter 4 4. Decide on the numbers, size and shapes of floaters of your fish cage. Use the styropor as floaters. 5. Cut and assemble ithe net barriers according to the dimension of the net enclosure and attach it to tha frame and provide sinkers. 6. Cut it according to your desired length. And attach them into the frame. Provide anchors as well. 7. Make a caretakers hut. Note: You can also use some other scrap materials aside from the suggested materials listed in this activity.
Post-Assessment Directions:Multiple Choice. Choose the letter with the correct answer. Write this in your test notebook. 1. What part of a floating fish cage nets are suspended? a. floaters b. anchors c. framework d. mooring lines 2. Which among the following is a disadvantage of culturing fish in fish cage? a. more man power requirement b. better control of fish population c. easier handling, inventory, and harvesting fish d. efficient control of fish competitors and predators 3. What is the first step in net cage fabrication? a. double lace every mesh b. rig all sinkers to the rib lines c. make splices on the four corners d. cut net according to the desired specification
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Quarter 4 4. What is the mesh size of net used in grow–out cages? a. 15 mm b. 20 mm c. 25 mm d. 30 mm 5. Why should bamboo poles or anahaw logs used in fish pen construction be cleared of sharp edges?
6.
a.
to prolong its life span
b.
to make staking easier
c.
to increase its buoyancy
d.
to prevent damage to the nets
What is the first step in fixing the net into the framework of a fish pen? a. Fix the net in place by driving bamboo pegs. b. Fasten double foot rope to the bamboo pole. c. Tie the head rope about 1.2 m above the water surface. d. Remove debris and other materials inside the enclosure
7. How do you align the poles to be installed between each of the guide poles? a. by using a rope b. by using of a transit c. by using a sighting device d. by using a bracing bamboo 8. It keeps the whole cage in a certain location to prevent towing the fish cage by water current. a. framework b. floating system c. mooring system d. netting assembly 9. Net fabrication will be based on the physical charateristics of the proposed site. This includes 212
Quarter 4 a. nature of water current b. characteristics of the cultured fish c. highest water levels or flood levels d. temperature and salinity of the water 10. The length of the nets is determined by multiplying the perimeter of the fish pen by a. 1.2 b. 1.3 c. 1.4 d. 1.5
Glossary Barrier. Something (such as a fence or natural obstacle) that prevents or blocks movement from one place to another Braid. To weave together (three or more strands or parts of something) Buoyancy. Ability of an object to float in water or air Creosote. A brown, oily liquid used to keep wood from rotting Diaphragm. A thin sheet of material forming a partition Fabrication. The action or process of manufacturing or inventing something Fluctuation. An irregular rising and falling in number or amount raised lines on a surface
Resources Republic of the Philippines, Department of Education. Public Technical Vocational High School Competency-based Learning Material. Third Year. Aquaculture NC II.
213
Quarter 4 Dela Cruz, C. R. et. al. FAO Fisheries Technical Paper Republic of the Phillipines, Fishpen and Cage Culture Development Project in Laguna de Bay, Republic of the Phillipines, Freshwater Aquaculture Centre: Central Luzon State University, Muñoz, Nueva Ecija. Toledo, C. 2009. AQUA203: Aquaculture Engineering. Lecture manual. Pangasinan State University, Binmaley Campus.
Merriam-webster.com www.bar.gov.ph
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