From Manual Sampling to Continuous Oxygen Intelligence

In Tasmania’s remote Macquarie Harbour, dissolved oxygen is more than a water-quality parameter.

It can directly influence aquaculture operations, environmental reporting, feeding decisions, and licence compliance.

Macquarie Harbour is a semi-enclosed estuary on Tasmania’s west coast. Its deep basin, limited water exchange, seasonal stratification, freshwater inflows and high organic loading create challenging conditions for salmon farming.

For operators working in this environment, occasional manual sampling is no longer enough.

What is needed is a monitoring system that can continuously answer four critical questions:

What is the oxygen level now?
Where is it changing?
Why is it changing?
What should the farm do when oxygen drops?

This is where an integrated Optical Dissolved Oxygen + Multi-Parameter Water Quality + LoRaWAN + Cloud Monitoring architecture can create value.

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01 | Why Dissolved Oxygen Has Become a Critical Aquaculture KPI

In intensive salmon farming, oxygen conditions can change rapidly with weather, water stratification, biomass, feeding activity and organic loading.

A sensor that only provides occasional readings may miss short-duration oxygen excursions.

Continuous monitoring changes the equation.

Key Monitoring Challenges

The Business Impact

The objective is not simply to measure oxygen.

The objective is to turn oxygen data into an operational decision:

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02 | The Honde Sensor Stack

A single parameter rarely explains the complete water-quality picture.

The Honde solution combines DO measurement with the physical and chemical parameters that influence oxygen dynamics.

Why Optical DO?

The fluorescence optical measurement principle offers several advantages for long-term aquaculture monitoring:

• No electrolyte replacement
• No oxygen consumption during measurement
• Low maintenance
• Stable long-term operation
• Suitable for low-oxygen environments
• RS485 Modbus-RTU communication
• Compatible with LoRaWAN, 4G, GPRS and WiFi
• Suitable for continuous online monitoring

This makes optical DO technology particularly attractive for remote cages and long-duration monitoring applications.

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03 | Why LoRaWAN Fits Remote Salmon Farms

Remote aquaculture sites create a difficult communication problem.

Cages may be located several kilometres from shore, while wired communication infrastructure is expensive or impractical to install.

A wireless architecture solves the connection problem.

IoT Monitoring Architecture

┌──────────────────────┐
│   Aquaculture Cages  │
│                      │
│  Optical DO Sensor   │
│  5-in-1 Water Probe  │
└──────────┬───────────┘
           │ RS485
           ▼
┌──────────────────────┐
│ Solar IoT Controller │
│ Data Logger / Logger │
└──────────┬───────────┘
           │ LoRaWAN
           ▼
┌──────────────────────┐
│   LoRaWAN Gateway    │
│     Shore / Buoy     │
└──────────┬───────────┘
           │ 4G
           ▼
┌──────────────────────┐
│    Cloud Platform    │
│ Real-time + History  │
│ MQTT / JSON Data     │
└──────────┬───────────┘
           │
     ┌─────┴─────┐
     ▼           ▼
┌─────────┐ ┌─────────────┐
│  Alarm  │ │ Compliance  │
│  Relay  │ │   Reports   │
└─────────┘ └─────────────┘

Why This Architecture?

Solar Power + LoRaWAN + 4G Backhaul

provides a practical architecture for remote water monitoring where cables are unavailable.

The system can transmit sensor data from cage-side equipment to a gateway and then to a cloud platform for centralized monitoring.

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04 | What the Monitoring System Actually Sees

The real value of continuous monitoring is not a single DO number.

It is the relationship between DO, temperature, salinity and pH over time.

Example Monitoring Baseline

*Target values should be configured according to the applicable site licence, operator requirements and local regulatory conditions.

The Important Point

When DO decreases, the operator needs more than a red warning number.

The system can also examine:

This creates a much more useful picture of the water column and environmental conditions.

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05 | From Sensor Data to Automatic Action

The strongest part of an IoT monitoring system is the final step:

A cloud platform can be configured with user-defined thresholds.

Example Alarm Logic

The actual thresholds should always be configured according to the applicable licence, welfare requirements and farm SOPs.

With an Alarm Relay System, the monitoring platform can send alerts to responsible personnel and, where the control architecture permits, trigger predefined operational actions.

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06 | Six-Month Monitoring Data: February–July 2026

A representative deployment scenario illustrates how continuous monitoring can transform environmental management.

Deployment

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DO Event Summary

What the Data Shows

55 monitoring events/readings were recorded below the 6.0 mg/L reference threshold during the six-month period.

Among them, 7 events dropped below 5.0 mg/L.

April accounted for the highest number of low-DO events, highlighting the importance of continuous monitoring during periods of stronger stratification.

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07 | The Four Numbers That Matter

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Suggested Data Visualization

Low-DO Events by Month

February   ██████████████ 14
March      █████████       9
April      █████████████████████ 21
May        ██████           6
June       ███              3
July       ██               2

Key Observation

The monitoring data shows a clear concentration of low-oxygen events during the earlier part of the deployment period. This is precisely where continuous monitoring provides value: the system detects short-duration excursions that periodic manual sampling may not capture.

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08 | Why the 5-in-1 Probe Matters

Dissolved oxygen is the critical parameter, but it does not operate independently.

The 5-in-1 probe adds environmental context.

Together:

creates a more complete environmental dataset than DO alone.

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09 | From Manual Sampling to Digital Compliance Evidence

Traditional manual sampling creates a fundamental limitation:

The operator only knows what happened at the moment the sample was taken.

Continuous monitoring creates a different evidence chain:

This enables operators to build a digital monitoring history containing:

• Timestamped DO measurements
• Cage identification
• Temperature trends
• Salinity trends
• pH trends
• Alarm records
• Threshold events
• Operator response records
• Historical trend charts

The result is not simply a sensor reading. It is a traceable environmental dataset that can support internal environmental management and applicable reporting requirements.

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10 | Why Optical DO + LoRaWAN Is Attractive for Remote Aquaculture

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11 | The Real ROI: Preventing Blind Spots

The value of a monitoring network should not be measured only by sensor price.

The bigger question is:

How much operational uncertainty does the system remove?

A continuous monitoring architecture can help operators:

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12 | One Platform, Multiple Aquaculture Applications

The same architecture can be adapted to different aquaculture environments.

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13 | The Global Demand Is Moving Toward Connected Water Monitoring

The Macquarie Harbour case reflects a broader trend across developed aquaculture markets.

As environmental monitoring requirements become more data-driven, operators increasingly need:

The same architecture can be adapted for aquaculture operations in:

• Australia
• Norway
• Canada
• Scotland
• Chile
• New Zealand
• Other regulated salmon and finfish farming markets

The procurement requirement is increasingly shifting from:

“Can you supply a DO sensor?”

to:

“Can you provide a complete, reliable and connected monitoring system?”

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14 | Honde Technology Aquaculture Monitoring Solution

Honde Technology provides a complete sensor-to-cloud architecture for water-quality monitoring.

Core Products

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15 | Build Your Aquaculture Monitoring System

Instead of purchasing individual sensors and integrating the communication system yourself, Honde Technology can provide a sensor-to-cloud monitoring solution.

Typical Architecture

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Final Takeaway

In remote aquaculture, the most valuable sensor is not necessarily the one with the lowest purchase price.

It is the sensor that can:

For oxygen-sensitive aquaculture environments, an integrated Optical DO + Multi-Parameter Probe + LoRaWAN + 4G + Cloud + Alarm Relay architecture turns water-quality monitoring from periodic sampling into a continuous operational intelligence system.

The future of aquaculture compliance is not more manual measurements.

It is better data, delivered continuously, connected to action.