Frozen Seafood Temperature Logs: The Importer’s Playbook to Accept, Hold, or Reject Shipments

A practical, step-by-step workflow from the Indonesia-Seafood team for using reefer and data logger records to make defensible decisions on frozen seafood deliveries—and to document claims when something goes wrong.

If you’ve ever stood at a cold dock with a million-dollar frozen load and a temperature log that “doesn’t look right,” you know the stomach drop. We’ve been there with buyers in Houston, Busan and Rotterdam. The good news is you can turn logs into clear decisions and solid claim evidence. Here’s the importer-side workflow we use with our own frozen shipments of IQF fillets, portions and tuna from Indonesia.

The three pillars of a defensible frozen-seafood temperature program

1. Set the right reefer conditions. Use a -18C setpoint for frozen seafood and keep vents closed. That’s standard across our portfolio, whether it’s Grouper Fillet (IQF), Yellowfin Saku (Sushi Grade) or Frozen Shrimp (Black Tiger, Vannamei & Wild Caught). Pre-trip inspections should be current, defrost schedules set, and controller sensors within calibration.

2. Place loggers smartly. Redundancy and placement beat brand selection. We prefer 4–6 data loggers per container with at least one product-simulant probe.

3. Define acceptance criteria before sailing. Most disputes happen because the PO/spec didn’t say what “acceptable” means. Put thresholds and actions in writing.

This leads us to how to run the shipment lifecycle.

Before loading: lock in specs, place loggers, document

• Purchase order and booking. State setpoint -18C, vents closed, and your acceptance criteria. Also state how many loggers, where they’ll be placed, and who downloads the reefer trip data.
• Reefer pre-trip inspection (PTI). Ask for the PTI pass record with sensor checks, fan and defrost tests. We ask for PTI within 30 days of sailing.
• Photo evidence. At stuffing, photograph the controller setpoint and supply/return display, the vent setting, and at least two logger serials with their placement.
• Logger placement in the container. Our baseline for IQF fish:
  • Bulkhead end: one logger in the top third, 30–50 cm from the front face of pallet.
  • Mid-bay center: one logger buried in a carton near the center pallet. If possible, run a probe into the middle of one box to mimic product core.
  • Near the doors: one logger 1–1.5 m from the doors, mid-height, not touching metal, to detect door heat ingress at discharge.
  • Sidewall: one logger mid-length, mid-height to catch airflow issues.
  • Optional: tape a small ambient logger just under the door gasket. It catches door openings and helps explain last-mile spikes.

Takeaway: if you only use one logger by the doors, you’ll see heat spikes that don’t represent the load. Spread them.

At discharge: a simple accept/hold/reject workflow

Start with seals and time. Record arrival time, seal integrity, ambient temperature, and how long the doors are open. Small details win claims later.

1. Download the reefer trip report. On Carrier units this is a “Trip Data” or “DataCorder” printout showing supply and return air, defrosts, alarms and setpoint history. On Thermo King, it’s similar. Note any “supply sensor fault,” “return high temp,” or “door” alarms.
2. Retrieve logger data. Keep files intact and avoid overwriting. Name them with container number, location, and serial.
3. Sample core temperature. Use a calibrated needle probe on a representative sample: front, middle, back. On IQF, we test several pieces together in a zip bag to avoid false highs from surface warming.
4. Decide: accept, hold or reject pending survey.

Here’s the thing. Air readings move fast. Product cores move slow. We never decide on air data alone.

How to interpret return vs supply air—and link to core

• Supply air is what the reefer unit pushes into the load. It should hover tight to setpoint. At -18C, a normal band is -17C to -19C most of the voyage, with brief swings during defrost.
• Return air is the warmest air coming back from the cargo. It’s always higher than supply. Large sustained gaps between return and supply can signal airflow blockage or heat ingress.
• Product core lags both. You’ll often see a small bump in return air at discharge. That doesn’t mean the fish thawed.

A practical rule we use when reading charts:

• A short return-air spike to -14C at opening, with supply still at -18C and cores ≤ -15C, is generally acceptable.
• A sustained return-air drift warming over many hours, paired with supply also drifting warmer than -18C, points to a reefer performance or power issue. That’s when we correlate with loggers and consider a claim.

Takeaway: compare supply, return and core together. Look for duration and trends, not single points.

Acceptance thresholds that actually work in practice

There isn’t a global law for seafood like there is for ice cream integrity. So we recommend you write thresholds into your contracts. Examples we’ve used with buyers:

• Setpoint: -18C supply, vents closed. Target supply average -18C ±1C for 95% of voyage. Accept brief defrost peaks.
• Excursions: no more than 2 cumulative hours above -12C on any logger, and no time above -10C. For sensitive items (sashimi-grade tuna saku), we tighten to “no time above -12C.”
• Core on arrival: accept if representative cores are ≤ -15C for IQF portions and fillets. If cores sit between -15C and -12C, hold for sensory and drip-loss checks. Above -12C, reject or survey.

These are commercially conservative. The key is clarity before sailing. If you need help tuning thresholds to your product mix, need help with your specific situation? Contact us on whatsapp.

Common mistakes we still see (and easy fixes)

• Only one logger at the doors. This exaggerates heat at discharge. Fix: place loggers front, middle and near doors.
• No product-simulant probe. Air moves too fast. Fix: put one probe inside a carton near the center pallet.
• Accepting or rejecting on a single high reading. Fix: use duration-based limits and core confirmation.
• Missing PTI and setpoint photos. Fix: make them a shipment deliverable, same as the packing list.
• Ignoring “return minus supply” delta. In our experience, a sustained delta above 6–8C mid-voyage can indicate airflow blockage or high heat load. That’s a red flag.

The key questions buyers ask us

What temperature should frozen seafood be kept at during ocean transit?

Use -18C setpoint. Supply air should stay close to -18C with brief defrost peaks. Return air will trend warmer than supply. For sensitive lines, some buyers choose -20C. Just align the entire chain on the spec.

How much time above -12C is acceptable before quality is affected?

We treat -12C as a practical excursion threshold for IQF seafood. Our default spec allows no more than 2 cumulative hours above -12C and none above -10C. Quality impact depends on product, glazing and packaging, so write product-specific limits into the PO.

Does a return-air reading of -14C mean my fish thawed?

No. Return air is not product core. A brief -14C at door opening is common. Check duration, check other loggers, and measure core. If cores are ≤ -15C and supply stayed near -18C, you likely have no loss.

Where should I place temperature loggers in a reefer container for seafood?

Use 4–6 units minimum. Place them at bulkhead top-third, mid-bay center (inside a carton), near the doors mid-height, and along a sidewall. Add one product-simulant probe and one ambient near the door gasket. Label locations and photograph placements.

How do I link data logger readings to core product temperature at delivery?

Correlate time stamps. You’ll usually see a spike on the “near-door” logger when doors open. Measure cores within minutes of that timestamp, on front/middle/back pallets. If the center logger stayed ≤ -15C and cores match, your load stayed frozen despite surface warming.

What documents do I need to file a temperature-related cargo claim?

Gather in one folder: PO/spec with temperature criteria, booking confirmation with setpoint, PTI record, stuffing photos (setpoint, vent, logger placement), bill of lading, packing list, reefer trip data download, all logger raw files and PDFs, arrival photos and timestamps, seal numbers, core temperature records, surveyor report, and any carrier alarm logs. Claims are won on consistency.

What should I do if the temperature logger didn’t record any data?

Don’t panic. Use the reefer trip report first. Pull Carrier/Thermo King alarms and temperature graph. Document core temperatures immediately on multiple pallets. Look for corroborating evidence: door logger, terminal gate-in/out EIRs, and power interruption records. Then keep the container intact and request a joint survey if quality is in doubt.

Bonus: reading reefer trip alarms without overreacting

• Defrost events. Brief supply/return increases are normal. Look for a quick return to setpoint.
• High return temp alarm. Investigate duration and whether supply also drifted. If supply stayed cold, it’s often a door-open or localized airflow issue.
• Sensor fault alarms. These weaken or nullify air readings. You’ll rely more on your independent loggers and core temps.

Takeaway: alarms are clues, not verdicts. Always cross-check with logger data and cores.

When to tighten or loosen the criteria

Tighten for high-value sashimi items, long transits through tropical ports, or light glazing. Loosen slightly for heavy-glazed, block-frozen or shorter voyages with fast cross-docks. The reality is your spec should reflect commodity, packaging and route risk.

Final word

Temperature logs are only scary when you don’t have a plan. With the right setpoint, smart logger placement, clear thresholds, and disciplined documentation, you can make fast, defensible decisions and stop arguing over single spikes. If you want product-specific thresholds for items like Grouper Bites (Portion Cut) or Mahi Mahi Portion (IQF), questions about your project? Call us. Or browse our export-ready range to match your program: View our products.