Good management of farm siting can help to mitigate such negative impacts as: the impingement on natural ecosystems (such as mangrove and wetlands) and the species that live within them; the discharge of sediment into natural waters; over-abstraction of freshwater supplies; and the salinisation of surrounding land and freshwater1, 2. Because inappropriate siting, design and construction of warm water prawn farm ponds can have negative impacts on resources and the environment, buyers should seek assurances from their suppliers that all national and local laws are adhered to, and that all farms have the required licences, permits and registrations in regards to their site and its operations, with documentation being kept to evidence compliance.
New farms should be located within appropriately identified aquaculture zones3 and ideally in areas where aquaculture development plans exist. Farm and pond developments should take place on land that has previously been used for agriculture or aquaculture (e.g. for at least 10 years). Existing and new farmers should consider carrying out assessments such as Biodiversity Environmental Impact Assessments (B-EIA) which are participatory and open in terms of results and outcomes. Where B-EIAs require rehabilitation of affected ecosystems then procedures should follow approved restoration guidelines.
New farms should not be situated in mangrove ecosystems or other natural wetlands of ecological importance, although allowance can be made for pumping stations and inlet/outlet canals providing they are permitted. Farms should ensure that ecological buffers, barriers and corridors are maintained through farms as required either by legislation or if identified by a B-EIA. Alternatively farms can work closely with the natural environment, as is the case with integrated prawn and mangrove farms4 for example. Contribution to environmental and social restoration funds may be possible where farms fall outside the above criteria.
To prevent salinisation of freshwater and soils earthen ponds should be lined, and there should be no discharge of saline water into natural freshwater bodies. Farms should also monitor and use appropriate testing methods to check salinity levels in resources such as freshwater wells, adjacent ecosystems and agricultural land, and in pond sludge that is collected for disposal outside the farm.
As warm water prawn farms are often located in coastal areas with relatively rich wildlife, species that prey on shellfish can be attracted to them. This can potentially cause problems due to direct losses as a result of predation, as well as having wider impacts on the stock due to stress and injuries. Warm water prawn farmers should ensure all possible management measures are taken to protect stocks from predators; this might be via netting of smaller ponds or fencing site perimeters. Deterrents, scarers and increased on-site activity may be effective and are preferable to lethal methods of predator control, which should only be resorted to when other methods have failed, and then only when appropriate licences are in place. Care should be taken to ensure that predator prevention does not potentially damage threatened, endangered or protected species.
Warm water prawn farms can apply for certification which ensures they address issues such as siting of the farm to avoid impacts in protected areas, discharge of earth into water bodies, negative impacts on endangered species and compliance with water abstraction limits, amongst other aspects. As many warm water prawn farms are small-scale concerns exist that certification may lead to a polarisation of larger farms from smaller ones, with the latter being unable to access export markets such as Europe. To address this, various programmes are supporting small-scale farmer cooperation, with the potential for multi-farm, or so called ‘cluster’ certification5, 6, 7.