Fish harvesting is a critical stage in fish farming that directly impacts the quality, yield, and profitability of aquaculture enterprises. For Agriculture and Extension professionals in Kenya, understanding efficient and sustainable harvesting methods is essential to support fish farmers in maximizing returns while preserving fish health and pond integrity. This chapter explores the tools and equipment used in harvesting, their appropriate applications, and the necessary maintenance practices to ensure longevity and effectiveness in Kenyan fish farming contexts.

4.1 Fish harvesting

Fish harvesting involves the systematic collection of mature fish from culture systems such as ponds, cages, or tanks. This process demands skillful use of specialized tools and equipment to minimize stress and injury to fish, thus preserving product quality. In Kenya, where fish farming contributes to food security and income generation, adopting best practices in harvesting is vital for smallholder farmers, cooperatives, and commercial enterprises alike.

4.1.1 Fish harvesting tools, equipment and materials

Fish harvesting depends on a variety of tools and equipment designed to capture fish efficiently and safely. Each tool has specific characteristics suited for different pond sizes, fish species, and harvesting methods. Selection of appropriate equipment ensures minimal fish damage, reduces labor intensity, and enhances harvest efficiency.

Cast Nets

• Design and Use: Cast nets are circular with evenly distributed weights on their periphery. They are thrown over a school of fish to trap them as the net sinks.
• Suitability: Ideal for harvesting fish in small ponds or cages where fish congregate near the surface.
• Advantages: Low cost and ease of use make them popular among small-scale farmers.
• Limitations: Effective only when fish are visible and concentrated; requires skillful throwing.

Seine Nets

• Design and Use: Seine nets have floats on the top edge and weights on the bottom, allowing them to hang vertically in water. They are dragged or encircled to herd fish.
• Suitability: Best for ponds with shallow waters and moderate surface area.
• Advantages: Can harvest a large number of fish in one operation.
• Limitations: Requires multiple operators and careful handling to prevent fish injury.

Fish Traps

• Design and Use: Made of bamboo or synthetic mesh, traps allow fish to enter but hinder their exit. They can be stationary or movable.
• Suitability: Useful in ponds with inlet/outlet channels or natural water bodies.
• Advantages: Passive harvesting reduces labor and fish stress.
• Limitations: Not suitable for large-scale immediate harvests; fish size limited by trap dimensions.

Landing Nets

• Design and Use: Handheld with a hoop frame and mesh net, landing nets scoop fish after capture.
• Suitability: Used during sorting, grading, or transferring fish after initial harvesting.
• Advantages: Minimizes fish handling and physical damage.
• Limitations: Labor-intensive for large quantities.

Fish Pumps

• Design and Use: Pumps equipped with fine mesh filters gently suction fish from confined spaces.
• Suitability: Common in hatcheries and small tank systems.
• Advantages: Reduces physical handling and stress on fish.
• Limitations: Requires power source and maintenance.

4.1.2 Uses of harvesting tools, equipment and materials

The choice of harvesting tools depends on pond size, fish species, harvest scale, and desired fish quality. Proper use of tools improves efficiency and reduces mortality, which is crucial for profitability and sustainability in Kenyan fish farms.

Efficient Harvesting Methods

• Selective Harvesting: Use of landing nets and traps to remove mature fish while leaving juveniles to grow, enhancing stock management.
• Bulk Harvesting: Seine nets and cast nets enable harvesting of large quantities quickly, suitable for final harvests.
• Minimizing Fish Stress: Fish pumps and gentle netting reduce handling injuries, preserving fish quality for market.

Handling and Transport

• Post-Harvest Handling: Landing nets allow careful transfer of fish to containers or transport tanks, reducing physical damage.
• Water Quality Maintenance: During harvesting, maintaining adequate oxygen levels and minimizing pond disturbance is essential to prevent fish mortality.
• Use of Materials: Containers such as aerated tanks or oxygenated bags are used in transporting harvested fish to markets or processing units.

Seasonal and Species Considerations

• Species Behavior: Tilapia may require different net sizes and techniques compared to catfish or trout.
• Harvest Timing: Early morning or late afternoon harvesting reduces fish stress due to cooler temperatures.
• Market Demand: Harvesting schedules are adjusted to meet market needs, ensuring fresh supply and optimal pricing.

4.1.3 Maintenance of harvesting tools and equipment

Proper maintenance of harvesting tools is necessary to prolong their lifespan, ensure operational efficiency, and prevent losses during harvesting. In Kenya’s rural and peri-urban fish farms, where resources may be limited, routine care is vital to sustain equipment functionality.

Cleaning and Drying

• Post-Use Washing: Nets and traps should be thoroughly rinsed with clean water after use to remove mud, algae, and fish slime that can degrade materials.
• Drying: Equipment must be dried completely in the sun to prevent mold growth and deterioration of fibers.
• Avoiding Chemical Exposure: Avoid contact with harsh chemicals or oils that weaken net fibers and metal parts.

Repair and Inspection

• Regular Inspection: Nets and traps should be checked for holes, tears, or broken frames before and after each use.
• Patching and Mending: Small holes in nets can be repaired with nylon twine or appropriate netting material to prevent fish escape.
• Equipment Lubrication: Moving parts of fish pumps require periodic lubrication to prevent rust and ensure smooth operation.

Storage Practices

• Proper Storage Areas: Equipment should be stored in dry, shaded locations to avoid UV damage and moisture accumulation.
• Avoiding Tangling: Nets should be folded or rolled neatly to prevent tangling and stretching.
• Security Measures: Secure storage prevents theft or damage by animals.

Calibration and Testing

• Functional Testing: Pumps and mechanical equipment should be tested regularly to confirm operational readiness.
• Replacement of Worn Parts: Timely replacement of worn or damaged parts reduces breakdowns during harvesting.
• Training on Maintenance: Farmers and extension officers should be trained on maintenance techniques to promote equipment longevity.

Chapter Summary

This chapter covers the essential aspects of fish harvesting, beginning with an overview of the various tools, equipment, and materials used in the process, including fishing nets, traps, and lines. It explains the specific uses of these harvesting implements and highlights the importance of proper maintenance to ensure their longevity and effectiveness. The chapter then explores different fish harvesting methods such as trawling, longlining, and purse seining, detailing how each technique operates and their suitability for various fishing environments. Fish processing is also addressed, emphasizing the steps necessary to prepare the catch for market or consumption. Finally, the chapter underscores the significance of keeping accurate fish records to monitor harvest quantities, track stock health, and support sustainable fish farming practices. Together, these topics provide a comprehensive understanding of the harvest phase in fish farming operations.