The Workshop produced a large volume of well-documented technical information. One very important aspect of the Workshop was the exchange of this information and related experiences among the participants. A second aspect was the crystalizing of ideas in regard to follow-up actions. Utilizing the prepared Summaries of the Sessions and Sectoral Meetings as a basis, the sponsors prepared a condensed summary of the major problem areas developed in the course of the Workshop and in addition a commentary and a set of recommendations on the follow-up actions that appear desirable. Some follow-up actions are noted as in-country, other as regional. SCSP and/or SEAFDEC propose to follow up on regional matters in consultation with the various Governments most concerned. Implementation by other interested agencies or institutions will also be welcome. With respect to in-country measures, various agencies and institutions will be consulted in regard to appropriate constructive measures to be taken. Some proposed actions are noted as both regional and in-country.
When major new reclamation, commercial, industrial or urban projects are proposed which could have significant impacts on aquaculture and fisheries, the environmental impacts should be evaluated and mitigating measures determined before, not after, the projects are constructed.
Commentary - All developing countries are in the process of intensively pursuing policies leading to increased industrial, commercial and urban development, often by land reclamation. An inevitable by-product of these developments is pollution which can and often does cause serious adverse effects on fisheries and aquaculture systems. Evaluation of these impacts is essential to determine whether mitigating measures are possible, or whether some alternative development plan could be less costly in terms of environmental impact. This appears to be almost entirely an in-country interest.
All proposed fishery projects should be carefully examined to determine that they do not create adverse environmental effects, as for example, significant flooding of drainage basins, sedimentation because of obstructive construction of fishponds in tidal swamplands and river estuaries, or erosion and ecological damage in coastal areas because of indiscriminate mangrove swamp removal. Essentially this means comprehensive planning and proper engineering designs so that human needs and environmental impacts can be balanced.
Commentary - There is increasing awareness that aquaculture projects can cause environmental damage, as well as be subject to environmental damage, as noted in the findings. The prevention of such environmental damage is essentially an in-country interest.
Physical factors of the environment such as climate, precipitation, flooding, storms, drought and other related factors need consideration in terms of departure from the average, as well as averages. Thus a 5-year drought or flood might well cause the failure of a project with a 10 to 20-year economic life, unless adequate design, operational and maintenance provisions are made.
Commentary - This is an in-country design responsibility.
A major concern of many aquaculture operations which use irrigation waters for their water supply is the effect of pesticides and herbicides on their operations. A determination of kinds and timing of pesticide/herbicide applications compatible with fish/rice culture, fish cage culture and other aquaculture forms is essential. In addition the suitability of pesticides used in fish culture should be considered.
Commentary - Some countries have now banned persistent pesticides of the chlorinated hydrocarbon type. New pesticides are coming into the market which are difficult and costly to analyze. Some governments such as Indonesia have adopted regulations requiring manufacturers of pesticides to pay for analyses and studies relative to their composition and effects before marketing is allowed. It appears that a regional cataloguing of pesticides and their toxicity characteristics could save costly duplication of effort between countries In-country action for control and regional cooperation in data gathering are considered desirable.
Oil spills are matters of serious concern in the countries bordering the Malacca Strait, and in Hong Kong and in other countries in the region with respect to adverse effects on fisheries and aquaculture.
Commentary - This is both an in-country and regional problem particularly with respect to possible major oil spill catastrophies. However, the proper forum for regional cooperation appears to be the ASEAN, or other regional or international body.
Manuals, guidelines, procedures and check lists are desired for fresh- brackish- and marine waters hatchery design, including both shrimp and fish culture, for small-scale projects (see par. 4.2.12). Items of particular interest include parameters on water quality requirements, control systems and methodologies for simple water treatment including sedimentation chambers, filters, aeration systems and water purification. Details of basic systems for fry production would be presented.
Commentary - It appears that such manuals could be prepared as a regional undertaking. The manuals could be utilized as a basis for in-country adaptation to needs of particular countries.
There is a marked shortage of small-scale hatcheries to produce all types of fry for production.
Commentary - This is essentially an in-country matter. However, the manuals noted under (i) could be valuable as an adjunct of increasing hatchery production.
The engineering and economic aspects of site selection with respect to surveys, soil and water quality, water control, biologic, environmental, and including socio-economic considerations are all matters which are generally common to most countries in the region. In making decisions about large-scale expansions of aquaculture, the Government often requires alternative site evaluations and ratings. A rating methodology giving due consideration to all the above parameters was considered highly desirable, as a means of decision making.
Commentary - The preparation of a site evaluation rating methodology appears possible as a regional endeavour. The methodology could be adapted to specific in-country needs as desired. It could also be integrated with the proposal following for a corresponding design manual for aquaculture projects.
There is a real need to provide specific engineering guidelines for pond design in as non-technical and understandable terms as possible. These guidelines, in the form of a manual, would apply to surveys, soil and water quality, water control, soil mechanics and site related engineering matters.
The aim would be to assist fish farmers, extension workers and field engineers in basics of design so that the quality of aquaculture pond and related systems can be improved at the least possible cost.
Commentary - The preparation of a regional scope manual was considered most desirable. The manual would then be adapted for in-country usage as desired.
The occurrence of acid sulfate soils is a matter of major importance in existing and proposed fishponds. Methods of treatment by lime application and application of animal manures are highly experimental and costly and uncertain in their results.
Commentary - This appears to be primarily a matter of concern in countries with extensive brackishwater aquaculture and is considered an in-country problem, in siting and design. In countries where brackish aquaculture is being introduced, care should be exercised in determining whether this condition exists.
In some areas of the Philippines where extensive or indiscriminate destruction of mangrove swamps has occurred through construction of brackishwater fishponds, there has been a marked increase in coastal erosion. Individual fish farmers have difficulty in coping with this erosion and therefore the proposal has been made that the Government should undertake the remedying of this coastal erosion on a comprehensive infrastructure basis, rather than the present unsuccessful, individual farmer, piece-meal basis. Such a basis presumably could be cost-sharing between Government and fish farmer groups.
Commentary - This appears to be entirely an in-country matter.
In many parts of Southeast Asia and in China there are widespread applications of a variety of techniques to utilize animal wastes, for nutrients in aquaculture production. Quantitative evaluations to balance waste inputs with fishpond nutrient requirements and production are lacking. Pig, duck and chicken wastes are commonly utilized, some pre-digested and some direct. Studies are needed to determine quantitative needs, as well as the most efficient means of nutrient production. In addition, pathogen transmittals need further study. Work programmed at AIT (CP 17) could be a significant step in this regard for the region. In-country efforts are needed to evaluate existing methodology.
Commentary - This appears to be essentially an in-country matter at the present time, but there are broad regional implications in any major breakthroughs to increase nutrient production for aquaculture purposes.
Fish cages. There is increasing interest in fish cage culture as evidenced by papers from Hong Kong, Indonesia, Malaysia, Philippines and Thailand. The several advantages of fish cage culture such as preservation of stock during flooding, opportunities for selective area culture, intensive stocking and feeding, and non-mixing of species make it increasingly attractive. In Indonesia and Thailand these are essentially small-scale operations. In Hong Kong larger scale operations, using rafts of cages, are being practised, where experiments with new materials are underway. A major problem in brackish and marine waters is to overcome fouling.
Commentary - Increasing use of cage culture is anticipated. Cage culture is practised in fresh-, brackish- and marine waters. The development of cage culture is considered essentially an in-country matter. However, a regional survey of practices could result in beneficial technology transfers.
Fishpens. The use of large area fishpens appears confined to Laguna de Bay in the Philippines. Pens of 0.25 ha to more than 10 ha have been constructed. Major problems have been encountered because of typhoon damage, pressures of massive movements of water hyacinth against the pens, deterioration of bamboo frameworks and nets in the lake water, and algal blooms causing fish mortality. A new circular truss design is under consideration. The suggestion was made that a floating pen cage design be considered, rather than a rigid framework type design.
Commentary - This is an essentially in-country matter.
The use of aerators to increase pond production and avoid mortalities is becoming increasingly prevalent. Aerators may be used only a few hours per day to compensate for diurnal minimum oxygen levels in fishponds, just before sunrise. A variety of aerating devices with varying efficiencies and applications are available.
Commentary - This is essentially an in-country matter.
The basics of pump design were presented, covering centrifugal, propeller, axial and mixed flow design units. The use of pumps was shown to greatly increase capabilities of utilizing lands not entirely suitable for filling and draining by gravity. However, costs and design
efficiencies in selection of pumps then become an important factor in considering their usage. The possibility of using wind operated pumps was of particular interest.
Commentary - This is essentially an in-country matter but could be covered as an adjunct to the engineering design manual noted in par. 4.2.4.
The simplest form of wave break for use inside large area fishponds is the installation of brush or bush wave breaks in lines to reduce the wave fetch. In coastal areas in Malaysia, underground reefs formed of pyramidal bunches of tires tied together have been utilized for both fish reef culture areas and shoreline protection. Major shoreline protection projects require full consideration of coastal mechanics theory of design; and may be necessary as an alternative to piecemeal protection as noted in par. 4.2.6.
Commentary - This is essentially an in-country matter.
In the region it is noted that some technological progress has been attained by private commercial aquaculture enterprises and research results from the government sector are just starting to filter into development projects. Concerted effort should be made so that the technological advances attained are transferred into the development and improvement of small-scale aquaculture ventures so that such ventures can be effective as an integral part of the overall rural development programme.
