Resources management in aquaculture
Fishermen in Ecuador catching wild shrimp from the sea
Many of the resources that aquaculture depends on are finite - water, land; inputs like seed, broodstock, feed ingredients. It is essential that the sector's resource use is managed so as to achieve long term sustainability and, in most cases, this means avoidance of adverse effects on the environment. At the same time, there are often conflicting demands on the resources aquaculture uses from other economic sectors; management decisions must then be made on the most appropriate distribution of what is available. The concept of economic efficiency can be useful in this process. In many cases aquaculture can be one of the most efficient users of resources in terms of the outputs it generates from a particular input - such as water, for instance. At the farmer level 'efficiency' can mean profitability and, as long as the inputs and outputs are given their proper value, sustainability also.
Decisions on resource use do not necessarily have to favour one sector at the expense of another. Aquaculture activities can frequently be integrated with other uses of water and land. Much aquaculture production occurs in small freshwater ponds that often have multiple uses. Fish production may be integrated with household waste disposal, poultry rearing or vegetable growing. In some cases, a pond may just be a by-product of an excavation to provide soil for house construction or road building. In other situations, aquaculture may be developed on land that is unsuitable for agriculture, due to the soil's low nutrient content, salinization or because of flooding.
In some kinds of aquaculture, integration with other interests can be more difficult. Balancing the farming of sea fish in cages or of oysters on moored systems in the sea, for instance, with the demands of tourism or fishing can be problematic. It is especially important in these cases that national and regional authorities develop a well thought out management plan, that this plan is prepared with the participation of the stakeholders and that it meets the aims of optimizing economic efficiency and sustainable use of the available resources.
The zoning of water and land areas for particular kinds of use, based on their physical characteristics and limitations, can be a useful start in the management process. It is also important that an understanding is reached of the social, environmental and biological constraints that exist. Problems have occurred with the expansion of shrimp farming, for instance, because of too narrow a focus in the planning process. Areas of land may have suitable soils, topography, ground cover etc. for development as shrimp ponds, but it is important neither to ignore the capacity of the local coastal environment to accept and reprocess the effluents that would be produced, nor the potential impacts on coastal peoples. Similarly in the salmon cage culture industry, it was not initially realized that disease considerations would set lower cage density limits than would be expected merely on the basis of prudent management of dissolved oxygen levels and feed inputs.
Satellite images, such as this one illustrating the hydrology of the Niger River basin, can be a useful planning tool
Aquaculture operations need seedstock and ideally these should come from hatcheries operating captive breeding programmes, without using animals captured from the wild. This first step towards domestication has been taken with comparatively few farmed species however. Management of the collection of wild stocks is a noted problem particularly in the shrimp, eel, and some sectors of the salmon farming industries. It is arguable that the collection of some seed from the wild, for instance of oyster spat, has no adverse effects on wild stocks and so guidelines have to be considered on a species by species basis, but the overall goal of domestication has merit.
Currently, there are also serious issues to be addressed as a result of the transfer of broodstock and seed stocks between regions and even continents. Disease and competition problems have resulted from many imprudent introductions and this is a key area that needs well-informed management. Scientists have worked to develop safe guidelines to assist managers in this area.
The management of feed and effluents are further important factors in optimizing aquaculture's resource use and minimizing adverse effects on local environments. The sources and costs of feed and feed ingredients affect the economic efficiency of production systems. The sinks where wasted and uneaten feed ends up always need consideration, but there should also be effort made towards avoiding the use of ingredients for feed that could have been used directly for human food. Secondly, formulations should strive to minimize net nutrient and faecal output. The technology exists to run many kinds of aquaculture so that the effluents contribute no net increase in nutrient load to the natural environment. While some sectors face practical or economic difficulties in achieving this, it is desirable that management strategies work towards it as a goal.
Improvements in efficiency of resource management in aquaculture have been recognized as prime considerations by many governments, aquaculture producers and other stakeholders.