Aquaculture Sustainability Calculator

The score is a composite index (0–100) derived from five weighted indicators: feed conversion ratio, carbon footprint per kg of fish produced, energy intensity, marine ingredient dependency in feed, and chemical/antibiotic use. Each indicator is benchmarked against published industry averages for the selected species and farming system. A higher score means better environmental performance.

FCR is the amount of dry feed required to produce 1 kg of live fish weight. It is calculated as total feed used divided by total harvest weight. A lower FCR means less feed is wasted and less pressure is placed on forage fish stocks and land-based feed crops. Typical FCR values range from about 1.0 for tilapia to 1.5 for salmon in well-managed systems.

The calculator converts each energy input to CO₂ equivalent using standard emission factors: electricity (~0.5 kg CO₂e/kWh on average grid), diesel (2.68 kg CO₂e/L), petrol (2.31 kg CO₂e/L), and natural gas (2.04 kg CO₂e/m³). Feed-related emissions are estimated based on the proportion of marine ingredients and plant-based ingredients. The total is divided by annual harvest weight to give a per-kg figure.

Yes. Select 'Oyster / Shellfish' as the farmed species. Shellfish require no supplemental feed and have minimal energy requirements, so they typically score very highly. Shellfish farming also provides nutrient removal services — oysters filter nitrogen and phosphorus from the water column, providing a measurable ecosystem benefit that contributes positively to the sustainability score.

Feeds high in fish meal and fish oil place greater pressure on wild forage fish populations and tend to have higher greenhouse gas footprints per kg. Feeds with a higher proportion of certified plant-based or alternative proteins (insect meal, single-cell protein) generally score better. The Marine Ingredient Dependency index reflects the combined fish meal and fish oil percentage, benchmarked against best-practice thresholds for each species.

Include all direct energy used in farm operations: electricity for aeration, pumping, lighting, and water treatment; diesel and petrol for boats, generators, and vehicles; and natural gas for heating. Do not include energy embedded in the manufacture of equipment or feed ingredients — those lifecycle factors are partly captured through the feed composition inputs.

Recirculating Aquaculture Systems (RAS/tanks) typically use far more electricity than pond or sea-cage systems but recycle nearly all water and produce highly concentrated waste streams that can be managed. Sea cages have low direct energy use but higher disease and escapement risks. Pond systems vary widely depending on aeration intensity and water exchange rates. The calculator applies system-specific emission and benchmark factors.

The most impactful levers are: reducing FCR through improved feed management and genetics, switching to lower-carbon energy sources (e.g., renewable electricity), reducing the marine ingredient fraction in feed, minimising unnecessary water exchange, and eliminating or reducing routine chemical and antibiotic use. The indicator breakdown table helps identify which areas offer the greatest improvement potential for your specific operation.