The differences between organic and non-organic (conventional) salmon farming are significant, primarily driven by the stricter regulations and principles governing organic certification bodies like the Soil Association. These differences aim to promote higher welfare standards, minimise environmental impact, and produce a more natural product.

In summary, organic salmon farming in the UK operates under a stricter set of standards aimed at promoting animal welfare, environmental protection, and a more “natural” product compared to conventional salmon farming.

Here’s a breakdown of the key distinctions:

Farming Methods
Organic Salmon:
* Lower Stocking Densities: Organic farms adhere to significantly lower stocking densities. For instance, organic salmon farms typically have a maximum ratio of 1% fish to 99% water (or 10 kg of fish per cubic meter), allowing the fish much more space to swim and shoal, mimicking their natural behaviour. This reduces stress, aggression, and the spread of disease.
* Location and Water Quality: Organic farms are often situated in areas with strong currents and excellent water quality, which helps to naturally disperse waste and keep the environment clean. This constant circulation reduces the build-up of seabed pollution from faeces and uneaten feed.
* Natural Life Cycle: Organic salmon are typically grown from organic smolts (juvenile fish) and reared to follow a more natural reproductive cycle, such as only in the spring.
* Environmental Harmony: The overarching principle is to work in harmony with the environment, aiming for a neutral marine footprint that does no harm to the ocean bottom or surrounding ecosystem.
* Segregation from Conventional Farms: Certified organic farms are required to be segregated from all neighbouring farms, including conventional ones, to minimise potential cross-contamination or disease spread.
Non-Organic (Conventional) Salmon:
* Higher Stocking Densities: Conventional farms typically have much higher stocking densities, sometimes as high as 20 kg/m³, which can lead to increased stress, fin damage, and a greater susceptibility to disease.
* Less Emphasis on Natural Conditions: While conventional farms also aim for efficiency, their primary focus is often on maximising production, which may sometimes compromise the natural conditions or welfare of the fish.
* Location Variability: Locations might be chosen more for logistical efficiency than for optimal natural water flow.

Substances Used
Organic Salmon:
* Strict Restrictions on Chemicals and Medications: The use of synthetic chemicals, antibiotics, and pesticides is severely restricted.
Antibiotics: Only allowed under strict veterinary prescription, and their use may result in the loss of organic status. They cannot be used prophylactically (preventatively).
Sea Lice Treatments: Certain harmful treatments like emamectin benzoate and azamethiphos are banned. While deltamethrin might be used, its usage is a third of that on non-organic farms, with strict withdrawal periods, and efforts are being made to prohibit its release into the environment. Organic farms often prioritise alternative methods like cleaner fish (wrasse and lumpfish) or physical removal, though sourcing of cleaner fish can be an issue.
Anti-foulants: Copper-based and other toxic anti-foulants are prohibited.
GMOs: Genetically modified organisms are strictly prohibited in the feed and for the salmon themselves.
Artificial Colouring: Only natural pigments are allowed in feed to enhance flesh colour.
* Approved Disinfectants: A limited list of allowed substances for disinfecting rearing systems and equipment (e.g., iodophors, calcium carbonate, hydrogen peroxide, organic acids) for use in the presence or absence of fis

Non-Organic (Conventional) Salmon:
* More Permitted Treatments: Conventional farms have a wider range of therapeutic agents, antibiotics, and pesticides available for use, often including those banned in organic systems. Antibiotics may be used preventatively.
* Synthetic Pigments: Synthetic pigments are commonly used in feed to achieve the desired pink flesh colour.
* Broader Range of Anti-foulants: May use a wider variety of anti-foulants to prevent marine growth on nets.
Feed

Organic Salmon:
* 100% Certified Organic Diet: The feed must be 100% certified organic, free from GMOs, synthetic pesticides, and growth hormones.
* Sustainable Fish Meal and Fish Oil: The fish meal and fish oil used must be derived from sustainable fisheries, prioritising trimmings and by-products from fish intended for human consumption (e.g., anchovy, herring, mackerel). This aims to reduce reliance on wild-caught fish specifically for feed.
* Limited Fish Oil Content: The overall fish oil content in organic feed is often limited (e.g., cannot exceed 28%), which can lead to a more natural growth rate and a lower risk of accumulating environmental contaminants.
* Plant-based Ingredients: Any plant-based ingredients must also be certified organic.
* Natural Astaxanthin: If astaxanthin is used for pigmentation, it must be derived primarily from organic sources or natural sources like Phaffia yeast.

Non-Organic (Conventional) Salmon:
* Wider Range of Feed Ingredients: Conventional salmon feed can include a broader range of ingredients, not all of which need to be organic.
* Variable Sourcing of Fish Meal/Oil: While efforts are being made to use more sustainable sources, conventional feed may still rely more heavily on wild-caught fish specifically for fish meal and fish oil.
* Higher Oil Content: “High-energy” feeds with higher oil content (e.g., up to 45%) may be used to accelerate growth rates.
* Synthetic Pigments: Synthetic pigments are commonly added to achieve the desired flesh colour.
* Potential for GMOs: While not all non-organic salmon are GM, there’s no blanket ban on GMO ingredients in feed unless specific regulations or farm practices prohibit it.