In Pond Raceway System: An Intensive Fish Production System - Dr. Jesse Chappell

Summary of Scientific Concepts and Technology in the In-Pond Raceway System (IPRS)

Overview:

• The In-Pond Raceway System (IPRS) is an advanced aquaculture technology designed to intensify fish production within earthen ponds.
• It contrasts with traditional pond culture by using a flowing water principle rather than static water.
• The system integrates raceway cells inside large ponds, with continuous water circulation driven by specialized aeration units called white water units (WWUs).

Key Scientific and Technical Concepts:

• System Design and Requirements:
  • Minimum pond size: 10,000 cubic meters per raceway cell (220 m³ per raceway).
  • Typically, 2-3 raceways per pond (20,000 to 30,000 m³ pond volume) for economic viability.
  • Raceway dimensions: 22 m long, 5 m wide, 2 m water depth.
  • Continuous electrical power required, with automatic backup generators to prevent system failure.
  • Only high-quality floating feed is used; no sinking feed or agricultural by-products.
  • The system is principle-driven; strict adherence to design and management is critical for success.
• Water Management:
  • Water is continuously circulated around and through raceways to maintain oxygen levels and remove waste.
  • white water units (floating aerators with regenerative blowers) create a robust, circular water flow.
  • Baffles are installed to lengthen water flow path and prevent short-circuiting of water flow.
  • Water exchange in raceways occurs every 5-7 minutes, exchanging the entire raceway volume 8-9 times per hour.
  • Flow velocity targeted around 8 cm/s to ensure fish comfort and effective waste transport.
• Aeration and Circulation Equipment:
  • white water units are floating, with no moving parts except the blower underneath a protective shroud.
  • Diffuser tubes (aerotube brand recommended) produce fine bubbles for efficient aeration and water movement.
  • Each raceway requires:
    • One blower for the raceway white water unit.
    • One blower for an associated open pond white water unit.
    • One supplementary blower for additional aeration when biomass reaches ~60%.
    • One spare blower for backup.
  • For ponds deeper than 3 meters, vertical mixing chimneys or additional white water units are used to maintain oxygen homogeneity.
• Fish Management and Production:
  • Fish are confined within raceways by upstream and downstream confinement gates made of metal frames and PVC-coated mesh.
  • Gates allow water flow but prevent fish escape and exclude wild fish from the quiescent zone.
  • The quiescent zone (6 m long) at the downstream end of the raceway allows settling of waste solids.
  • Target production per 10,000 m³ pond volume:
    • 33 tons of fed species per cycle.
    • 7.5 tons of non-fed "service" or filtering species in open pond water.
  • Staggered stocking and harvesting of multiple raceways allows continuous production.
• Waste Management:
  • The pond acts as a biological filter, maintaining aerobic conditions through thorough mixing.
  • Waste solids settle in the quiescent zone and are removed mechanically 3-4 times daily using oscillating vacuum heads.
  • Waste removal systems use semi-solid pumps and a cable-driven carriage to efficiently collect and pump solids to shore-based settling tanks.
  • The system is designed as zero discharge; removed solids are used as fertilizer for crops.
  • Proper pond bottom preparation (removal of vegetation, shaping) is critical to avoid oxygen depletion and ensure efficient water flow.
• Construction and Operation:
  • Raceway walls constructed from brick, concrete, and reinforced steel bars.
  • Floors are thin concrete slabs supported by footers.
  • Working walkways are installed for feeding and maintenance, avoiding obstruction of gates and white water units.
  • Electrical installations must follow strict safety protocols due to proximity to water.
  • backup generators should be tested regularly under load, and staff trained with fire drills for power outage scenarios.
• Key Principles for Success:
  • Follow design parameters strictly (pond volume per raceway, flow rates, equipment specifications).
  • Use only recommended equipment (e.g., aerotube diffusers, Gast regenerative blowers).
  • Maintain continuous operation of water circulation and aeration.
  • Properly manage stocking density and harvest timing to avoid exceeding peak biomass.
  • Efficiently remove waste solids to reduce oxygen demand and maintain water quality.
  • Ensure reliable electrical power with automatic backup systems.
  • Maintain and clean equipment regularly (e.g., blower filters, diffuser racks).

Methodology / Setup Outline:

• Pond Preparation:
  • Ensure pond volume ≥ 10,000 m³ per raceway.
  • Remove organic vegetation and shape pond bottom.
  • Combine smaller ponds if possible for economic efficiency.