Integrated Production Systems and Harvest Procedures

Why Harvest Planning Matters

A successful harvest does not begin when the first net hits the water — it begins days before, in the planning room. Poor planning causes fish stress, weight loss, mortality, and food-safety failures that can cost a facility its market. Every commercial aquaculture site operates from a written harvest standard operating procedure (SOP). Before you touch any equipment, read that SOP and follow it.

Feed Withdrawal

Feed withdrawal — stopping feed delivery for a set period before harvest — serves two purposes. First, it empties the gut, which reduces the chance of fecal contamination during processing and improves flesh quality. Second, fish that are not actively digesting are more tolerant of the crowding and handling stress that harvest creates.

Withdrawal time is species- and market-form dependent. A live-haul market may require a shorter withdrawal than a round-weight fresh market. Warmwater species in high summer may need a longer period than coldwater fish at low temperature because digestion rate changes with water temperature. Always follow the facility SOP and any buyer specifications in writing — do not guess.

Equipment Inspection

Before harvest day, inspect every piece of equipment:

• Seines and dip nets — check for holes, frayed leads, and broken floats. A hole lets fish escape; a broken lead lets the net belly up off the bottom.
• Fish grader — confirm bar spacing matches the target market grades. Spin a trommel grader by hand to check for stuck rollers or broken welds. Bar graders should be clean and free of debris.
• Digital scale — zero the scale with an empty container, then verify with a known weight if available. Record the scale ID and last calibration date on your harvest record sheet.
• Ice chest or live-haul tank — ice chests must be pre-chilled and drained. Live-haul tanks must be running, aerated, and at or near harvest pond temperature before fish are loaded. A sudden temperature shock can kill a load.
• PPE — rubber aprons, waterproof boots with slip-resistant soles, and nitrile or rubber gloves are required for all personnel handling fish or operating in wet harvest areas. Wet surfaces are slip hazards. Never work alone near open water or tanks deep enough to pose a drowning risk.

The Harvest Sequence

Step 1 — Crowding. Deploy the seine across the pond or tank and walk it toward one end, concentrating fish in a shallow area. Move slowly and steadily; rapid movement spikes stress hormones and can cause fish to pile and suffocate. Keep a watch on dissolved oxygen (DO) — crowding sharply drops DO. Have emergency aeration ready.

Step 2 — Dip-netting and transfer. Dip fish from the crowded area in manageable loads. Avoid overfilling the dip net; fish crushed at the bottom of a heavy net suffer scale loss and injury. Transfer fish promptly to the counting/weighing station or directly to grade.

Step 3 — Grading. Run fish through the grader to separate market grades (for example, large, medium, and small). Keep each grade separate from this point forward. Grades that do not meet market specifications are typically sold to a secondary market or held for grow-out.

Step 4 — Counting and weighing. Weigh each grade in a tared container. Count a sub-sample of fish (for example, count 10 fish and weigh them) to calculate an average individual weight, then use total weight to estimate total count. Record all weights and counts immediately — do not rely on memory.

Step 5 — Loading. Load fish into the designated container — ice for round-weight fresh market, live-haul tank for live delivery. Maintain the cold chain: fresh fish must reach the required chilled temperature quickly. Live-haul tanks must maintain adequate DO and temperature throughout transport.

Food Safety and the Temperature Chain

Once fish destined for fresh or processed markets leave the water, time and temperature control begins. Keep fresh fish on ice or at refrigerated temperatures without interruption. Any break in the cold chain — sitting on a warm dock, delay in icing — accelerates bacterial growth and shortens shelf life. Document the time fish came out of the water and the time they were placed on ice or in refrigeration on your harvest record sheet.

Post-Harvest Documentation

Accurate records protect the facility legally and help improve future production. Your harvest record sheet must include: species, tank or pond ID, date and time, final harvest biomass by grade, total mortality observed during harvest, water temperature, disposition (buyer name or storage location), and the name of each person who worked the harvest.

Compare your total harvest weight against your earlier standing-crop biomass estimate. Calculate variance:

Yield variance (%) = ((Estimated biomass − Actual harvest weight) ÷ Estimated biomass) × 100

A positive number means you overestimated; negative means you underestimated. Large variances signal problems with your earlier sampling methods and should be noted for improvement.

Safety Summary

• Wear slip-resistant boots and rubber aprons at all times near harvest areas.
• Never work alone near open water.
• Monitor DO continuously during crowding; have aeration on standby.
• Inspect all electrical equipment (aerators, pumps) before use near water — follow lockout/tagout procedures when servicing any equipment.
• Lift nets and containers using proper body mechanics; harvest equipment can be heavy when wet.