In China, the industrial super-intensive culture (ISIC) model for shrimp has gained ground. However, choosing the right technology is vital for sustainability and profitability.
A recent study published by researchers from Ocean University of China, the Yellow Sea Fisheries Research Institute, and the Qingdao Marine Science and Technology Center conducted a bioeconomic analysis comparing two predominant technologies in the industrial farming of Litopenaeus vannamei shrimp: the water exchange system and the recirculating aquaculture system (RAS). This analysis, published in the journal Aquaculture Reports, offers valuable information for producers’ decision-making.
Why Compare Shrimp Farming Systems?
Super-intensive shrimp culture (ISIC), with densities of 600 to 1200 shrimp/m3, aims for high yields. The traditional water exchange model uses treated water (seawater or groundwater), achieving good economic benefits by being less dependent on seasons. However, the high stocking density requires rigorous water quality control and raises concerns about high water consumption and effluent discharge that can cause eutrophication.
On the other hand, the recirculating aquaculture system (RAS) reuses water after a purification process (physical and biological filtration, disinfection, etc.). RAS promises lower environmental impact, better water conservation, and potentially lower disease incidence, positioning itself as a future direction for efficient aquaculture. However, it still faces technical barriers and lacks consolidated experience. Objectively evaluating both systems through economic analysis is fundamental for optimizing production.
Methodology: A Bioeconomic Approach
To understand the complexities of each system, the researchers applied a bioeconomic approach. This method integrates the biological growth of the shrimp with the economic aspects of production (costs, revenue, profits).
The study was conducted in commercial facilities in Qingdao (China) in 2022. Tanks under a water exchange model (control, with approx. 20% daily exchange) were compared with tanks in an RAS system operating at three recirculation intensities: low (0.5m3/h), medium (1.0m3/h), and high (1.5m3/h). All tanks started with L. vannamei juveniles averaging 0.92 g, fed similarly.
Key statistical analyses were performed:
- Structural Equation Modeling (SEM): To assess how different water quality factors (Nitrogen, Phosphorus, COD) indirectly impact the final shrimp weight.
- Mixed Effects Model: To analyze the direct effect of the system type (exchange vs. RAS at different intensities) on the average final weight.
- Cost-Benefit Analysis: Detailing variable costs (larvae, feed, medicines, energy, temporary labor, etc.) and fixed costs (rent, fixed salaries, maintenance, depreciation, etc.) for each model.
- Marginal Benefit Analysis: To measure how unit changes in shrimp price or shrimp weight affect revenue in each system.
Key Results: Productive Efficiency and Water Quality
Impact of Water Quality
The SEM analysis revealed that water quality factors have an indirect negative effect on the final shrimp weight in these intensive systems.
- Chemical Oxygen Demand (COD) and Phosphorus compounds showed the most significant negative impact (coefficients of -0.375 and -0.397, respectively).
- Interactions were observed: Phosphorus compounds negatively impacted Nitrogen compounds (-0.311), while COD had an indirect positive effect on Nitrogen compounds (0.594). This underscores the complexity of water quality management and the importance of controlling P and COD.
Performance by System: Water Exchange Leads
The mixed-effects model showed clear differences in growth:
- The water exchange system contributed significantly more to the final shrimp weight compared to all RAS intensities (P<0.001). This aligns with previous studies indicating higher yields in well-managed exchange systems.
- Within RAS, the moderate recirculation intensity (1.0m3/h) had the highest positive impact on the average final weight. Very high or low intensities resulted in lower growth.
Specific growth rates (SGR) reflected these findings:
- Water exchange: 14.93 %/day
- Moderate RAS: 13.36 %/day
- Low RAS: 11.26 %/day
- High RAS: 11.06 %/day
Economic Analysis: Costs and Profitability
Cost Breakdown
The cost analysis showed that the RAS model had higher total costs (US$ 940.91 ha−1) than the water exchange model (US$ 835.42 ha−1).
- The main difference was in the electricity cost, representing 43.11% of the total cost in RAS (due to the recirculation system) versus 27.47% in the exchange system.
- Other significant costs were Nutrition and Medicines (17.34% in RAS, 22.10% in exchange). These findings are consistent with other studies pointing to higher fixed and operational costs in RAS, especially for energy and maintenance.
Revenue, Net Profits, and Margins
Despite higher costs, the difference in yield tipped the economic balance:
- Total Revenue: US$ 1306.76 ha−1 (Exchange) vs. US$ 1064.90 ha−1 (RAS).
- Net Profit: US$ 471.34 ha−1 (Exchange) vs. US$ 124.00 ha−1 (RAS).
- Cost-Benefit Margin: 56.42% (Exchange) vs. 13.18% (RAS).
The water exchange system, under the studied conditions, proved considerably more profitable.
Economic Sensitivity: The Impact of Price and Weight
The marginal benefit analysis explored how variations in price and final weight affect profitability:
Price Impact:
- In the water exchange model, for every dollar increase in shrimp price, revenue increases by 1.33 units.
- In RAS, the greatest impact was seen with moderate intensity, where each dollar increase in price raised revenue by 1.16 units.Weight Impact:
- In the water exchange model, for each unit (e.g., gram) increase in average shrimp weight, revenue increases by 30.3 units.
- In RAS, again, moderate intensity was the most positively sensitive, with a 26.3 unit increase in revenue per additional unit of weight.
These results confirm that both selling price and final weight (specification) are crucial factors for profitability in both systems, but the exchange system showed greater positive sensitivity, reflecting its higher base net profit.
Discussion and Implications for the Shrimp Industry
This bioeconomic analysis offers several important conclusions for shrimp producers in intensive systems:
- Water Quality is Key, but Complex: While factors like N and P negatively affect growth, their interactions and the influence of COD are complex. Comprehensive management is necessary.
- Water Exchange (Well-Managed) Remains Highly Competitive: In terms of yield and economic profitability, the water exchange system proved superior under the study conditions, likely due to technology maturity and the favorable farming environment it creates.
- RAS Potential Depends on Optimization: Although RAS had lower overall profitability, moderate recirculation intensity proved most efficient within this system, both in growth and marginal economic response. This suggests optimizing the recirculation rate is crucial for improving RAS viability. Adjusting intensity can narrow the economic gap with exchange systems.
- Operational Costs (Energy) are a Critical Point in RAS: The high energy cost of RAS is a significant economic barrier that needs addressing to improve its competitiveness.
- Price and Final Weight Define Success: Regardless of the system, achieving good final weight and favorable prices are determinants of profitability. However, the study suggests current technological constraints in RAS may limit final shrimp size, affecting profitability.
Conclusion: Balancing Economics and Ecology
The study concludes that while the water exchange system currently offers greater economic profitability in super-intensive L. vannamei shrimp farming, the RAS system, particularly with an optimized (moderate) recirculation intensity, holds potential. Improving RAS technology, for example, with the use of Artificial Intelligence, to reduce costs (especially energy) and optimize shrimp growth is fundamental to making it more competitive.
As the industry seeks more sustainable systems with lower environmental impact, the continuous development and optimization of RAS are essential. This bioeconomic analysis provides a solid foundation for producers to make informed decisions, considering both the economic benefits and operational challenges of each technology in intensive shrimp farming.
Contact
Jian Li
Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences
Qingdao 266071, China
Email: bigbird@ysfri.ac.cn
Reference (open access)
Wang, Y., Chen, Z., Wang, J., Chang, Z., Zhang, S., Meng, G., & Li, J. (2025). Neoclassical economic analysis of water exchange and recirculating aquaculture systems in shrimp farming. Aquaculture Reports, 42, 102800. https://doi.org/10.1016/j.aqrep.2025.102800
Editor at the digital magazine AquaHoy. He holds a degree in Aquaculture Biology from the National University of Santa (UNS) and a Master’s degree in Science and Innovation Management from the Polytechnic University of Valencia, with postgraduate diplomas in Business Innovation and Innovation Management. He possesses extensive experience in the aquaculture and fisheries sector, having led the Fisheries Innovation Unit of the National Program for Innovation in Fisheries and Aquaculture (PNIPA). He has served as a senior consultant in technology watch, an innovation project formulator and advisor, and a lecturer at UNS. He is a member of the Peruvian College of Biologists and was recognized by the World Aquaculture Society (WAS) in 2016 for his contribution to aquaculture.
