A Major Breakthrough in Complete Eel Farming: The Impact of the "New Mass-Production Tank" That Reduced Juvenile Fish Costs from 40,000 Yen to 1,800 Yen

Table of Contents

1. Introduction: "Doyo no Ushi no Hi" and the Eel Crisis

2. Issues with Dependency on Wild Glass Eels

3. Overview of Technological Innovations

   • 3-1 Collaborative Research Framework and Project Background

   • 3-2 Design Philosophy of the New Mass-Production Tank

   • 3-3 Fluid Analysis and Feeding Automation

4. Dramatic Changes in Cost Structure

5. Verification of Survival Rate and Growth Performance

6. Commercialization Roadmap and Industrial Impact

7. Ripple Effects on the International Community

8. Sustainability Assessment and Environmental Impact

9. Impact on Consumer Prices and Distribution

10. Future Challenges and Outlook

11. Conclusion

1. Introduction: "Doyo no Ushi no Hi" and the Eel Crisis

Every summer, news is filled with reports of the soaring prices of "unaju" (grilled eel over rice). The backdrop to this is the decline in the catch of wild glass eels and the strengthening of international trade regulations (CITES Appendix II). Domestic aquaculture industries are forced to purchase juvenile eels at high prices from overseas, leading to a normalization of price transfers. Complete aquaculture technology has long been called a "dream technology," but its biggest hurdle has been the "cost of mass-producing juvenile eels."

2. Issues with Dependency on Wild Glass Eels

• Resource Depletion: The catch in Japanese coastal waters has plummeted from 232 tons in the 1960s to around 5 tons in recent years.

• Rising Purchase Prices: Recent transaction prices have remained high at 500-600 yen per eel.

• International Criticism: The Japanese eel is listed as Critically Endangered on the IUCN Red List, and there is strong CSR pressure from overseas markets.

3. Overview of Technological Innovations

3-1 Collaborative Research Framework and Project Background

Since fiscal year 2017, a project commissioned by the Fisheries Agency has seen collaboration between FRA, Yanmar HD, and Marino Forum 21. To solve the issues of declining survival rates and high costs in existing 1000L large tanks, they have conducted research on shape optimization and materials prtimes.jpyanmar.com.

3-2 Design Philosophy of the New Mass-Production Tank

• Size: Horizontal cylinder with a diameter of 40 cm × length of 150 cm

• Material: Adoption of FRP (Fiber Reinforced Plastic) significantly reduces manufacturing costs

• Internal Flow Field: Yanmar's CFD analysis ensures adequate circulation and oxygen supply

• Capacity Efficiency: 1,000 eels per tank, with one worker able to manage four tanks

3-3 Fluid Analysis and Feeding Automation

An automatic feeding device is incorporated to disperse shark egg powder-based feed in small amounts and at high frequency. This minimizes feed loss and prevents water quality deterioration. FRA tests maintained growth and survival rates (approximately 65-70%) equivalent to small 5L tanks.

4. Dramatic Changes in Cost Structure

Labor costs compressed from about 70% to 25%, and material costs from about 20% to 10%. The automation ratio reached 60% at the trial stage.

5. Verification of Survival Rate and Growth Performance

Growth rates decrease with diameters over 50 cm, but a 40 cm diameter maintains growth speeds equal to or greater than small tanks yanmar.com. Additionally, extending the axial length does not affect survival rates, allowing for expansion to 1.5 m in length. Long-term breeding tests reported an average body length of 5.8 cm and an average survival rate of 68% after 30 days.

6. Commercialization Roadmap and Industrial Impact

1. 2026 FY: Demonstration farm (100 tanks) with an annual production of 100,000 eels

2. 2028 FY: Integrate IoT with automatic feeding and water quality monitoring for 90% labor reduction

3. 2030 FY: Aim for an annual production of 1 million eels per facility, with costs in the low 1,000 yen range
   
   

Replacing just 1% of the domestic consumption (100 million eels annually) is expected to create a market worth approximately 5 billion yen.

7. Ripple Effects on the International Community

• With the export restrictions on European eels (Anguilla anguilla), the Hong Kong and Chinese markets are under pressure, presenting new export opportunities for Japanese-produced fully farmed glass eels.

• CITES Compliance: Artificial seedlings are likely to be treated outside the quota, expanding legal distribution channels.

• Technology Licensing: Joint research proposals are pouring in from aquaculture companies in Southeast Asia.

8. Sustainability Assessment and Environmental Impact

LCA estimates show a reduction of about 45% in greenhouse gas emissions compared to the traditional wild capture route. FRP tanks are lightweight, reducing CO₂ emissions during transport. By adopting a closed-loop system for wastewater treatment, nitrogen emissions are reduced by 40%.

9. Impact on Consumer Prices and Distribution

If the cost of juvenile eels drops from 40,000 yen to 1,800 yen, there is room for a price reduction of "300-500 yen per grilled eel," even after accounting for processing and distribution costs. Offering eel dishes in the mid-1,000 yen range on "Doyo no Ushi no Hi" is within sight, and restaurant chains are considering menu expansions.

10. Future Challenges and Outlook

• Complete Automation of Feeding: AI control for 24-hour operation to reduce feed loss by 10%

• Ensuring Genetic Diversity: Risks of inbreeding depression in closed systems

• Consumer Understanding: PR regarding taste and nutritional differences between artificial seedlings and wild eels

• International Standardization: Export strategy through obtaining third-party certifications like ASC and BAP

11. Conclusion

The new mass-production tank by FRA has become a decisive factor in elevating complete eel aquaculture from the "research stage" to the "industrial phase." As a model case that balances resource management and the preservation of food culture, it can be said to be a technological innovation that provides significant insights to the global aquaculture industry.

🔗List of Reference Articles (External Links, in Date Order)

• Yanmar Holdings "Development of a New Eel Seedling Mass-Production Tank Contributing to a Significant Reduction in Glass Eel Production Costs" (July 8, 2025)

• Fisheries Research and Education Agency Press Release (July 8, 2025)

• Chugoku Shimbun Digital "Development of New Tanks for Glass Eel Mass Production" (July 8, 2025)

• Nippon.com "Japanese Aquaculture Technology Could Make Eel Dishes Cheaper" (July 25, 2024)

• Seafood Media "Glass eels now cost 1,821 yen each, a step towards social implementation" (July 2024)

• J-PlatPat Patent Information Platform "Patent No. 7606689: Tank for Breeding Larvae and Larvae Breeding Device" (December 18, 2024)