Mapping and Measuring Aquaculture in Palau
Region Oceania & Pacific
Summary
In Palau, urgent food security needs and environmental pressures are driving rapid development of marine aquaculture, but without effective regulatory frameworks and sufficient comprehensive spatial planning, this expansion risks harming biodiversity and local coastal communities. To address this gap, a NASA-funded project led by The Nature Conservancy developed a multi-criteria decision analysis (MCDA) and interactive mapping decision support tool (DST) for aquaculture planning. Using NASA Earth observation data, the tools help identify suitable aquaculture sites and support environmental regulation.
Key outcomes from the project include:
- An online spatial planning and mapping DST built on the results of the MCDA. This web tool is currently used by multiple Palauan states and has been integrated into national master planning to prioritize new aquaculture locations.
- A published Guidance Manual for Marine Aquaculture Spatial Planning and Management distributed to all states and the Bureau of Fisheries that provides country-level case studies, risk assessments, and siting guidelines.
- Hands-on ArcGIS capacity-building training for Palauan stakeholders and students, ensuring the country can independently manage sustainable aquaculture siting long-term.
Conducted between November 2018 and May 2023, the project aimed to demonstrate a replicable model that could eventually be scaled to other Small Island Developing States. To evaluate the success and legacy of these interventions, the Space Science Institute (SSI), in partnership with TNC and the Republic of Palau, is now undertaking an impact assessment also funded under NASA’s Ecological Conservation program. This assessment, led by PI Annie Holland of SSI, will determine the utilization, quality, and long-term socioeconomic and environmental impacts of the project on the people of Palau, setting the stage for these tools to be effectively leveraged for sustainable aquaculture development worldwide.
Value Chain Diagram
Decide
- Identify suitable locations for clam and finfish aquaculture
- Avoid conflicts with marine protected areas, tourism, and navigation
- Reduce environmental impacts and disease transmission risks
- Support permitting and aquaculture planning decisions
Apply
- Aquaculture siting guidelines: guides identification of the major factors constraining siting of aquaculture operations.
- Constraints analysis: identifies spatial locations associated with major constraining factors as defined by the aquaculture siting guidelines and excludes them from further consideration for aquaculture development.
- Ecological forecasting and biophysical suitability models: identifies suitable, resilient locations for aquaculture development.
- Online mapping decision support tool: communicates the results of the constraints analysis and modeling efforts.
Data production
- Aquaculture siting guidelines
- Constraints analysis
- Ecological forecasting and biophysical suitability models for aquaculture development
- Online mapping decision support tool (Palau Aquaculture Suitability)
Sense
- Aqua MODIS satellite imagery (Sea Surface Temperature, Chlorophyll α)
- Multi-scale Ultra-high Resolution (MUR) Sea Surface Temperature
- Landsat 8 Satellite Derived Bathymetry
Decision-Making Context and Needs
Palau is home to a unique and vulnerable marine ecosystem located within the highly biodiverse "Coral Triangle." While expanding marine aquaculture is essential for the nation’s food security, development has been constrained by limited governance capacity and decision-support tools. Farmers often must conduct costly, individual Environmental Assessments (EAs) and siting analyses to secure farm loans and prove that their proposed locations will minimize negative water quality impacts on fragile coral reefs ecosystems. However, most applicants lack the technical capacity and resources to conduct such complex analyses, which often require spatial data.
To overcome these barriers, the spatial planning tools developed by TNC are designed to support the following management and regulatory decisions:
- Site Selection: Identifying locations of greatest opportunity for aquaculture development, such as areas with appropriate, stable water temperatures to support fish health.
- Environmental Protection: Excluding locations where environmental conflicts are greatest, ensuring farms are not sited on top of, adjacent to, or in close proximity of, sensitive coral reefs where bad water quality can damage them.
- Disease Management: Siting farms at a sufficient distance from one another to reduce the likelihood of fish disease or pest connectivity via ocean currents.
- Government Permitting and Financing: Informing regulatory conditions to facilitate a streamlined permitting and loan approval process for local farmers who previously could not meet EA requirements.
If Palau's aquaculture growth develops rapidly without a sound siting governance in place, the consequences for the region's 400 coral species and 1,300 varieties of reef fish could be detrimental. To address this, TNC leveraged NASA Earth observations to evaluate oceanic conditions at a large scale. Satellite data supported models identifying suitable aquaculture locations while minimizing impacts on sensitive habitats. This work has helped facilitate the permitting process for local farmers and contribute to more sustainable aquaculture growth in Palau.
Earth Observation Data Products and Information
The project has produced and used EO-derived products that directly address the decision needs described above. Key products include:
- Sea Surface Temperature: Measuring upper and lower temperature limits helps ensure that sites are suitable for aquaculture species, whose physiological tolerances can vary widely.
- Chlorophyll a: While chlorophyll a indicates phytoplankton availability for filter-feeding species, high concentrations may also reflect excess nutrients or eutrophication; thus, sites with elevated levels should be avoided.
- Water current speed and direction: Current speeds must remain below gear limits while maintaining sufficient flow and direction to disperse build-up of fish and feed waste.
- Salinity: Upper and lower salinity limits define key physiological tolerances for aquaculture species and vary widely among species.
- Significant Wave Height and Direction: Aquaculture gear has upper limits for maximum tolerable wave heights. Waves that are too high make it difficult to visit a site to feed and maintain gear. If severe, gear can become dislodged or break apart.
- Satellite-derived bathymetry: Water depth determines the suitability, stability, and environmental impact of aquaculture systems, including gear deployment, mooring requirements, and waste dispersion.
Satellite Earth observation data were used to generate indicators for assessing aquaculture suitability across ecological and social criteria to support spatial planning.
- Aqua MODIS for deriving sea surface temperature (Mean, Variation, and Minimum/Maximum; over a 17-year time series) and Chlorophyll a (Mean and Variation over a 17-year time series) through ocean color remote sensing.
- MUR (Multi-scale Ultra-high Resolution) for deriving sea surface temperature since 2002; Combines infrared and microwave data from various satellites and ship/buoy data, available from 2002 to the present for ocean research and forecasting.
- AVISO for measuring significant wave height and direction (Mean, Variation, and Maximum over a 10-year time series).
- Landsat 8 for satellite-derived bathymetry (see Wei and Theuerkauf, 2021 for methods used).
Impacts and Benefits
For NASA’s Ecological Conservation Program, project success is defined by its tangible impact on the decision-making and operational activities of end-users, leading to measurable conservation outcomes, improved efficiency, or socioeconomic gains. However, quantifying this impact is inherently challenging due to the time lag between project completion and real-world results, as well as the complex nature of decision-making. Because capturing these long-term benefits is a top priority, the current impact assessment, undertaken by the Space Science Institute in partnership with TNC, seeks to gather concrete examples from the Palau aquaculture project to demonstrate exactly how Earth observation products informed decisions, drove specific actions, and produced real-world consequences.
Designed to produce measurable value by converting NASA Earth observations into actionable spatial planning tools, TNC project's outcomes are already being utilized to protect marine ecosystems and support livelihoods. Benefits observed and evidenced to date include:
- Strategic Master Planning and Regulation: The Ngiwal State Planning Commission (NSPC) utilized maps generated from the project's Palau Aquaculture Sustainability DST to inform the comprehensive Ngiwal State Master Plan.
- Co-Development and Technical Capacity Building: The Bureau of Fisheries actively shaped the Palau Aquaculture Suitability DST and participated in targeted mentorship, building internal technical capacity to manage these tools long-term.
- Community Outreach and Extension Support: The Bureau of Fisheries leveraged the spatial data to disseminate best practices directly to local communities.
- Scientific Advancement and Replicable Methodology: The project's innovative multitemporal approach for satellite-derived bathymetry was published in a peer-reviewed journal, providing a replicable methodology for other coastal nations facing data limitations.
The ongoing evaluation combines document review and stakeholder interviews to assess tool uptake, usability, and impacts on planning and permitting.
Preliminary Evaluation Insights
Preliminary interviews conducted for the impact evaluation are already demonstrating the tool's significant operational and social value. Stakeholders emphasize how the integration of NASA satellite data has streamlined resources and empowered local regulatory processes:
- Improving Operational Efficiency: Fabio Siksei, Fisheries Development Coordinator at the Bureau of Fisheries, highlighted how the tool saves critical time and resources in the field. "I think NASA did a great job of developing that tool, especially with the satellite technology and imagery," Siksei noted. "Sometimes we'll do the desktop exercise through that tool and then after we still have the ground truth it, but at least we've kind of had an idea. And that also helps us prepare when we go through the actual site visit and run through everything like farm construction."
- Building Community Trust and Guiding Leasing Decisions: Lincy Marino, Project Manager at the Ministry of Agriculture, Fisheries and Environment, emphasized the importance of the co-development process and the trust in the NASA brand. "NASA and TNC had worked with the community to build the tool, which is very important to us... because those are the people that we're trying to help," Marino explained. She also highlighted its direct regulatory application: "In Palau... the farmer wants to build a farm, they go to the state, and the state leases them a water area... we'll work directly with the state to identify where those areas are so that farmers down the line are more successful in growing their farms than putting them somewhere that's probably not suitable."
Through this ongoing data collection, the impact evaluation will verify these preliminary results and provide formal updates on how well TNC has achieved its intended objectives. The evaluation is measuring uptake of the DST, growth in technical capacity, use of spatial analysis in permitting decisions, and longer-term improvements in aquaculture governance. Capturing these tangible outcomes will ultimately provide NASA with the methodological approaches needed to evaluate and guide conservation impact globally.
Scaling for Global Impact
Building upon its project in Palau, TNC launched new aquaculture siting projects in 2022 in critical geographies, including Mexico and the African Great Lakes. Looking ahead, TNC has established a 10 x 2030 plan to conserve more than 10% of the world's ocean by 2030, with a focus on sustainable fishing and better-managed marine areas, and they hope to strategically scale this work to priority geographies. By evaluating indicators of environmental health, aquaculture production, seafood consumption, social resilience (including food insecurity & vulnerability), and economic influences, TNC has identified 17 countries that could immediately benefit from investment in a smart growth approach.