Because fish and shrimp farming requires a source of brackish water, ponds are normally constructed close the sea or estuaries. Before the tsunami many ponds were constructed in an ad hoc manner without detailed site assessment. The aquaculture ponds in Aceh received the full force of the tsunami due to a lack of greenbelts and wave dissipating structures. The tsunami also exposed large quantities of acid sulfate soils. The tsunami wiped out thousands of kilometers of dykes and also caused damage to canals, ponds and hatcheries. Domestic and industrial debris, along with sediments, were deposited in canals and ponds. The extent and nature of this damage has been assessed by FAO and MMAF (Phillips and Budhiman, 2006).

 

The two most problematic soils types in Aceh are acid sulfate soils and sandy textured soils. Both soils are common along the coastline. Acid sulfate soils contain a mineral called pyrite which oxidises when exposed to oxygen. The oxidation process releases large amounts of sulfuric acid and mobilizes metals which are toxic to fish and shrimp. Damage to dykes and sluice gates has exposed acid sulfate soils to oxygen on every low tide since the tsunami. Consequently acid production in ponds is now greater than before the tsunami and threatens the productivity of restored ponds. Furthermore, acid sulfate soils present a risk to the reconstruction effort because fresh acid-producing sediments are likely to be disturbed by excavators and used to reconstruct dykes.

 

If acid sulfate soils are not managed they will cause:

Sandy soils are a common problem in Pidie and occur in pockets at other locations. These soils are best avoided outright because dykes constructed in sandy soils are unstable and are prone to leakage and erosion. Although sandy soils are easy to identify, excavator operators and farmers are often unaware of the engineering limitations of these sediments. Dykes and canals constructed in sandy soils can degrade within days of reconstruction and will eventually fail to control water.

 

Although acid sulfate and sandy soils are easily identified in the field, proper soil assessment still requires skill. Soils need to be assessed and remediated before ponds can be reconstructed and stocked. Long term pond management also requires a good understanding of soils. An understanding of soil properties is necessary for:

The ACIAR project is characterizing and mapping soil properties at key locations. Expert soil and mapping staff from UNSW and Gadjah Mada University are undertaking the work.  The results of these activities are being disseminated to the relevant stakeholders. Compressed copies of maps will be made available on the links page.

 

 

Accurate hydrological data are scarce in Aceh due to a lack of hydrological gauging stations, long term data sets, and changes to the coastline caused by the earthquake and the tsunami. The tsunami also damaged existing gauging stations.

 

An understanding of tidal, surface and groundwater hydrology is necessary to:

 

The current project is measuring and modeling the hydrology of the redevelopment areas and designing alternative pond layouts.

 

 

Disease is a common problem in coastal aquaculture and the risk of outbreaks is now high in Aceh due to a lack of testing for specific diseases in hatchery broodstock and post larvae, and a lack of understanding of disease prevention and management strategies at the farm level.

 

The most common shrimp disease threat is White Spot Disease (WSD). Outbreaks of WSD can cause significant production losses and affect the export potential of the industry. Proper disease screening, diagnosis and management are urgently required.

 

ACIAR and the AARP are developing strategies to manage disease including the establishment of mobile- and laboratory-based testing facilities and services, training stakeholders in disease assessment and management, and the development of an extension program. Laboratory technicians at CBAD are being trained in cutting-edge disease diagnosis.

 

 

The redevelopment of ponds requires careful assessment of each site to account for the environmental problems discussed in the above sections. Site assessment is also required to avoid social impacts. In some cases a return to past culture systems is not possible because of:

Site selection criteria are needed to address these issues and to identify alternative land use and/or select new areas that are more suitable for aquaculture. Aquaculture alternatives, such as seaweed production or polyculture, that are a more sustainable replacement for shrimp or fish monoculture, are also under consideration.

 

The exposure of ASS, increased disease risk, modified pond layouts and other changes will require improved pond management practices to enable the redeveloped industry to cope with new pressures and also meet the requirements of sustainable and environmentally responsible shrimp farming.

 

Site selection criteria, site assessment and pond management methods developed under ACIAR Projects FIS/97/22 and FIS/2002/076 are being adapted to the situation in Aceh and disseminated through the current project's extension program in collaboration with the AARP. Aceh-specific information is also currently available in the form of technical notes (see links page).