REPORTS OF WORKING GROUPS
WORKING GROUP I
| Topic: | Layout and Design of Aquaculture Projects: Pond Systems |
| Chairman: | Engr. P.L. Torres, Jr. |
| Members : | Engr. E.S. Martinez |
| Engr. A. Abordo | |
| Engr. H. Serna | |
| Engr. P.F. Subosa | |
| Engr. S.J. Jaspe | |
| Engr. N. del Rosario | |
| Engr. M. Arenas | |
| Engr. V.N. Alferez |
SUMMARY
| State-of-the-art | Problems | Recommendations |
|---|---|---|
| Milkfish | ||
| Pond | ||
| a. Area | Grow-out: design of big areas relating to management of H2O, harvesting, pond preparation, etc. | Determine what is the maximum manageable area. |
| b. Shape — rectangular — square — irregular | None | None |
| c. Orientation | No control on the even distribution of lablab. | Disseminate available information on use of substrates. Disseminate information on long side perpendicular to prevailing wind direction. |
| d. Pond layout — 4 types | None | Disseminate the modular system. |
| e. Depth — 40 cm | None | None |
| Shrimp | ||
| Perimeter dike | ||
| E1 = HT + FB Plus 1 m for shrinkage and settlement | Too steep for non-clay material. | Make flatter clay loam. Should be at least 1:1.5 clay (1 m vertical to 1.5 m horizontal). |
| SS = V:H = 3:1 to 1:1 Crown — minimum of 2 m wide | In practice most are steep than desirable. | Open pond gate as soon as tide water reaches pond water level. |
| Main supply canal dike | ||
| H= (HSP — GS) + MR + FB I — SS | ||
| Partition dike | ||
| Minimum of 1 m for crown | Two gates are needed in pond, but should be flow through or not? | Let in water and let out simultaneously or let in and allow for a while before letting it out. |
| Gates | Should the gates be in the center or corners? Determine relative sizes of supply and exit gates. | Appropriate agency should be asked to set up a hydraulics laboratory. Continue present study at LRS of SEAFDEC on gate location and on water circulation and flow using dye. |
| Sluice gate or monk gate | ||
| Square gate is better than other forms | Should gates for entry and discharge be the same (sluice and monk) or different. Entrance gate to be bigger than exit? | Entrance gate should be bigger than discharge gate. |
| Area | ||
| Different areas | Difficulty in management. | Less than 2 ha is recommended. |
| Shape | ||
| Any shape | Ratio of length on the width | Determine ideal ratio: width = 50–100 m |
| Orientation Any | Pond should be parallel to wind direction Install wind breaker or wave breaker when necessary. |
WORKING GROUP II
| Topic: | Layout and Design of Aquaculture: Pen and Cage Systems |
| Chairman: | Engr. O.K. Yu |
| Members : | Engr. A.E. Misagal Engr. R. Demafiles Engr. C.Y. Villodres Dr. A.G. Lambert Arch. V.S. Traviña |
| State-of-the-art | Problems | Recommendations |
|---|---|---|
| Definition | ||
| For purposes of clarity, the group decided to first define a fishpen and fishcage. | ||
| The fishpen was defined as an enclosure with a side structure but no bottom structure. The sides are fixed or embedded in the bottom and placed in an area with a water depth of 2–6 meters. It usually has an area of 1 ha or more. | Best design and best material to use for fishpens. Optimum size or area to be used. | Conduct experiments to answer problems. |
| A fish cage is an enclosure with side and bottom structures, supported by a frame, either fixed or floating. It usually occupies a small surface area. There are three types of fishcages: (1) floating cage —this is a kind of fishcage which is supported by a floating framework. It is anchored to ensure a fixed position; (2) fixed cage — is a kind of fishcage that is supported by a framework that is embedded on the soil bed, and (3) sub-merged cage — is a fishcage with sides, top and bottom totally sub-merged under water and anchored. | The effect of suspended bottom and embedded fishcage on rate of growth of fish. Egg collection from broodstock cages. | Undertake further verification experiment regarding the effect of suspended and embedded bottom net of the fishcage on the growth rate of fish. Disseminate and transfer aquaculture hatchery technology to users. Milkfish should be made to spawn in land-based hatchery. |
| Utilization | ||
Fishpens | ||
| Fishpens in Laguna Lake is a booming industry. In 1973, there were only 5 000 ha of fishpen, but in 1983, there were over 30 000 ha. This shows that it is a very profitable industry. | Availability of fingerlings at fluctuating level Poaching | Use electronic gadgets to deter would-be poachers. The government should organize livelihood projects around the area. |
| Materials used are bamboo poles for framework, anahaw trunks and wooden posts. Polyethelene nets are used in the submerged or unexposed portions of the pens while polyester nets are used for the exposed portions of the net 1 m below the water surface. | Scarcity of local materials used for pens and cages. The prices are also getting high. | Alternative construction materials should be identified. Use of anti-fouling chemicals and knotless nets. In Laguna Lake, the pens should be designed to minimize destructive effects of water hyacinth. |
| The posts are manually embedded, first by aligning and once the line is fixed, it is pushed by 4–8 people using their own body weights. | Recommend the improvement of the quality of materials manufactured locally. | |
| Floats are used as a precaution against typhoons. These floats prevent escape of fish when the nets become submerged when the frames collapsed. | Typhoons. | Monitor weather reports closely and conduct frequent inspection of pens and cages especially during typhoon forecasts. |
| The Laguna Lake fishpens follow the traditional method of construction. The most successful method is followed and do not consider engineering principles. | Referential design data are not available, i.e., soil bearing capacity of the lake, tensile and durability of bamboo and anahaw poles, etc. | Use alternative designs which use few material inputs. |
| Fishcages | ||
| Fishcages are extensively used in Laguna Lake. At present, these are usually constructed on the shallow portions of the lake. The materials used are bamboos for framework, polyethelene and nylon nets. Recently, polyester nets have been introduced which have been found to be more resistant to sunlight effect. These are used at the upper portion of the nets that are exposed to sunlight. | ||
| SEAFDEC also uses fish-cages at its lgang Sub-station for transition grow-out for milkfish, siganid, and P. monodon broodstock and broodstock maturation. The cages used serve the research needs of the Department. | Fouling. The corrosive action of the sea/sea breeze and exposed metals greatly affect installation by and in the sea. | Search for pen/cage construction materials that are corrosion-free. |
WORKING GROUP III
| Topic : | Layout and Design of Aquaculture Projects: Tanks and Other Land-Based Systems |
| Chairman : | Dr. R.R. Platon |
| Members : | Engr. M. Mendoza, Jr. Engr. J.R. Espinosa Engr. H.A. Palma Engr. A.T. Vizcarra Engr. S.A. Tillo Engr. P.M. Gavieta Engr. J.T. Canto, Jr. Engr. O. Millamena Engr. P.V. Canoso |
| State-of-the-art | Problems | Recommendations | |
|---|---|---|---|
| 1. | LIFE SUPPORT SYSTEM | ||
| 1.1 | Aeration a. Blowers b. Aerators c. Air pumps (aquarium type) | Capacity flexibility to match requirements. Expensive blowers (mostly imported). | Variable RPM electricity motor. a) Vari-pulley Explore other means of aeration, e.g., Venturi type. |
| 1.2 | Water supply (for intake system) a. Filtration gallery b.Wells Sea Fresh c. Sewerage water system | Clogging. Biofouling, freshwater intrusion, sand intrusion. Applicability to sheltered areas. | Efficient mechanical cleaning. Use of conical reamer carbide tip. |
| Treatment | |||
| Gravity sand filter | Mechanical backwashing. | ||
| Rapid sand filter | Mechanical backwashing. | ||
| Activated carbon filter | Future course of action. | ||
| Disinfection | |||
| Chlorination | Handling. | Safety measures. | |
| Piping system | |||
| PVC pipes | Deterioration due to sunlight. | Insulation. | |
| Polyethelene valves | Expensive, breakage. | Improvement of design. | |
| 1.3 | Light | ||
| a. Solar | |||
| b. Artificial light | |||
| 2. | CULTURE SYSTEM (TANKS) | ||
| 2.1 | Shrimp species | ||
| a. Broodstock tanks Circular Rectangular | Role of substrates not determined. Critical minimum volume. Stress during stage determination. | Determine location of dead volume. For studies. | |
| b. Hatchery tanks Shape | Evaluation of hydraulic characteristics. | ||
| — Circular | |||
| — Rectangular | |||
| Size | |||
| From 2–200 tons | Leaks. | ||
| Materials | |||
| — Concrete | |||
| — Fiberglass | |||
| — Ferrocement | |||
| — Bamboo-plastic lined | |||
| Aeration (based on circulation patterns) | Optimum level usually unknown. | ||
| c. Nursery tanks Shape | Operational methods regarding safety. | Standardization of shape, size and operation of tanks. | |
| — Rectangular — Square | Service walkways slippery. | Improvement of design of nursery tanks. | |
| Size | |||
| From 10–50 tons (depth 1–3 m) | |||
| Aeration | |||
| — Airstones | |||
| — Airlift pipe | |||
| — Substrates | Evaluate use of substrates. | ||
| Monitoring of water quality | Need for more efficient monitoring. | Provision of adequate monitoring and control of set-up | |
| — Dissolved oxygen | |||
| — pH | |||
| — Salinity | |||
| — Temperature | |||
| 3. | WASTE DISPOSAL | ||
| Discharge point near intake | Unintentional recycling of waste. | Hydrological/meteorological study. | |
| Further studies on the use of recycling/biofiltration. |
WORKING GROUP IV
| Topic: | Equipment, Materials and Methods in Construction and Management |
| Chairman: | Engr. R. C. Sison |
| Members: | Engr. J. P. Yaptangco, Jr. Engr. J. B. Uy Engr. A. V. Guevara Arch. W. J. Barros Arch. J. Quines Engr. R. Lagoc Ms. L. Avance Mr. E. Pador Engr. R. Padlan |
| State-of-the-art | Problems | Recommendations | |
|---|---|---|---|
| 1. | APPLICATION OF PRE-CASE CONCRETE IN AQUACULTURE | ||
| 1.1 | Pre-casting maybe applied to all concrete structure used in aquaculture including infrastructure support facilities | Lack of information dissemination on pre-casting as a method of construction. On the methodology of pre-casting. | Intensive dissemination of information on pre-casting as a method of fabrication and the need for sub-surface analysis. |
| Extensive use of pre-cast on design and construction of gates have been noted | — Connection/jointing. — Water proofing/sealing. — Handling/transport. — Curing. — Storage. | Identification of appropriate water proofing materials/sealants. | |
| Pre-casting is pre-sently applied in fabricating aquaculture components like tanks and other support facilities | Stability of gate foundation has been identified as a major cause of failure. | Explore possibility of using indigenous materials in pre-casting. | |
| Use of concrete/ ferrocement pre-cast in aquaculture has also been noted | |||
| 2. | AERATORS | ||
| 2.1 | Expanded use of aerating devices in hatcheries, nurseries and in grow-out ponds specially for shrimp culture. | Identification of appropriate type of aerator for specific aquaculture application. | Further evaluation of different types of aerators for specific purposes both for technical and economic feasibility. |
| 3. | PUMPS | ||
| 3.1 | Axial, centrifugal and propeller type of pumps are the most commonly used in aquaculture | Identification of the most proper/ efficient pump for specific applications. Lack of technical skills in installing and operating the equipment. | Further evaluation of types of pumps in use. Intensive information dissemination on the result of the above. Training of personnel involved both in installation and operation. |
