Applications of Finer-Scale Geospatial Information and Analysis to Support the Sustainable Management of Silvofisheries-Based BrackishWAter Aquaculture: A Case Study from Subang Regency, West Java Province-Indonesia

An integrated mangrove and low-density brackishwater aquaculture system also known as "silvofisheries" has been practiced in Indonesia since the 1970s, for the purpose of mangrove conservation, increased incomes from fish products and food security. The sustainable development and management of silvofisheries require the availability of effective spatial information, tools and analysis. This study presents model applications of finer-scale geospatial information and analysis to support the sustainable management of silvofisheries-based brackishwater aquaculture in Subang Regency, West Java Province, Indonesia.

WorldView-2 multispectral satellite imagery with a spatial resolution of 2 m was used to extract brackishwater aquaculture geospatial information (Figure 1A).  Environmental data used for simulation was obtained from Research Institute for Coastal Aquaculture (RICA) in Maros, South Sulawesi, Indonesia. To demonstrate the major geospatial issues and phenomena on the existing silvofisheries pond in the study site, GIS-based spatial analysis such as vector-image conversion, interpolation and geospatial statistical models were employed.

The results indicate that geospatial data analysis provides quick analytical process and display of spatial features of pond design like canal networks, pond layout and mangrove: water area ratio. A single feature of pond unit can have various attributes such as the status of land ownership, biophysical characteristics, bio-economic status and aquaculture management history. The characteristics of these attributes might change over time, thus require a cycle of regular monitoring. Using spatial data of land elevation and local tide data (3D-View in Figure 1B) this study discovered the presence of hydrological constraints due to ineffective tidal flushing to supply the required volume and quality of seawater to support the silvofisheries. Salinity of pond water ranging from 0 to 65 ppt was also found to be a significant limiting factor to pond productivity in the study area. This wide range in salinity values was relating to high spatial variation of pond bed elevation and ineffectual canal due to high sedimentation rate reducing water exchange. Geospatial information and analysis simplicity should be used to encourage local environmental managers or governments as well as other aquaculture stakeholders participatory in applications to help sustain productivity and conservation objectives of the existing silvofisheries programs in Indonesia.