Farmed Cod

| 1st September 2003
Already on sale in some British supermarkets, is farmed cod really the long-term solution to the problem of declining wild populations.
By Tom Hargreaves

Marks and Spencer has recently sold the UK’s first farmed cod to consumers. The cod came from the UK’s first commercial cod farm – situated on the shores of Scotland’s Loch Striven (pictured right). Many more cod farms are proposed, particularly in Shetland, and large numbers of salmon farmers are considering diversifying into this new branch of aquaculture.

Historically, it used to be possible to catch vast numbers of Atlantic cod supposedly just by lowering a basket into the ocean and scooping them out. Today, wild populations of the fish are almost extinct. The EU is constantly reducing fishing quotas for cod, but it may be that the only way wild populations will recover is through a complete ban. Cod farming is being hailed as the salvation of the dwindling cod fishing industry, but the broader truth is that we eat too much of the fish.

Cod-Farming techniques
Captive females are mated with wild-caught males. Artificial light is used to encourage spawning out of season. Once hatched, juvenile fish are given antibiotics and vaccinated against diseases before being stored in seawater-filled tanks. For “on-growing” to market size the cod are graded according to size so as to counter their cannibalistic tendencies, and may be transferred to sea cages.

Adding Pressure to Fish Stocks
While cod farming is supposed to benefit wild stocks, the feed required actually contributes to the depletion of the wild fish. Adult cod are fed on fish-meal pellets that are made out of fish oil extracted from “trash fish”. It is estimated that four kilograms of fish are required to produce one kilogram of farmed cod. This trebles the pressure on marine fisheries, harming natural food chains and making it harder for wild cod stocks to recover.

Poor Conditions
Farmed cod are stocked at high densities, with up to 1,000 fish per tank. This density leads to deoxygenated water. In addition to this, the fish are constantly transferred from one over-crowded tank to another.

Harming the Fish
The poor conditions farmed cod are subjected to cause physiological deformities. Over-crowded tanks cause the fish to rub tails and fins, which then become damaged. Overcrowding also increases the risk of disease and lice being passed from fish to fish. And the fish’s oily diet causes their livers to swell up.

Destroying the Marine Environment
Waste and uneaten feed from cod sea cages are spread on the seabed, fouling it and causing deoxygenisation. This leads to localised destruction of the marine environment, which can harm population levels of other fish and bottom-feeding animals like prawns.

Bad for Consumers
Farmed cod look and taste similar to wild cod, but processors have a legal duty to label farmed cod. A ‘farmed’ label tells the consumer that the fish contains residues from the antibiotics and vaccines used to control disease among cod. ‘Organic’ farmed cod has been dubbed a ‘consumer con’; it contains and ‘bio-accumulates’ PCBs and dioxins from the wild-caught fish used in fish-meal pellet feed.

Adult cod are carnivorous and will eat almost anything, swimming as they do with their mouths open. They feed mainly on smaller fatty fishes such as herring, capelin, sand eels, shrimp and squid, however. They can’t see more than a few feet ahead, and rely on their sense of smell to find food. In 1994, a Dutch fisherman caught a cod with a set of dentures in its belly. In 1532, British fishermen fought with the Hanseatic League in the first of many ‘cod wars’. Some believe it was the Basques who were the first people to encounter North America thanks to their fishing expeditions, which took them further and further west in search of cod.

4 different continents have eaten cod in hundreds of different recipes over the last 1,000 years

7 per cent of the cod consumed in the UK comes from the North or Irish Seas; 85 per cent comes from Iceland, Norway, the Faroes and Russia

10 per cent of all fish caught worldwide is cod 15th century – when John Cabot arrived in what are now Canadian waters cod were supposed to be so plentiful in the sea that they impeded the progress of his ship

30 number of years cod can live for

40 kg/m3 – said to be the “successful” stocking density of cod tanks and cages

45 per cent – the cut placed on cod quotas by the EU in December 2001; this reduced North and Irish Sea catches from 49,000 to 29,000 tonnes

211 pounds – the record weight for a caught cod (the fish in question was more than six feet long); most fish caught today weigh between five and 14 pounds

1,000 the number of cod that farms frequently store in a single tank

150,000 tonnes of cod currently consumed in the UK each year 7 million eggs laid by a single female each spawning season; most females lay between 4 and

7 million eggs laid by a single female each spawning season; most females lay between 4 and 7 million

This article first appeared in the Ecologist September 2003

More from this author


The Ecologist has a formidable reputation built on fifty years of investigative journalism and compelling commentary from writers across the world. Now, as we face the compound crises of climate breakdown, biodiversity collapse and social injustice, the need for rigorous, trusted and ethical journalism has never been greater. This is the moment to consolidate, connect and rise to meet the challenges of our changing world. The Ecologist is owned and published by the Resurgence Trust. Support The Resurgence Trust from as little as £1. Thank you. Donate now.