Conventionally farmed fish

Despite its emergence as a newly developed primary sector, fish farming can trace its origins to regions of china where it was first practiced several thousand years ago. Edible carp, eel, and catfish, were cultivated in reservoirs linking the canal networks used for crop irrigation. These farms were low intensity by today’s standards and had the advantage of collaborative resource efficiency. Because they used natural materials and sought to maintain the biological integrity of their product the farms were, in effect, organic.

On account of global competition and economic rationalisation, most fish farms are now designed to deliver high yields. In order to meet their production targets, conventional aquaculture farms frequently engage in husbandry practices which are harmful to their stock and potentially unsafe for the consumer.

Controlling the lifecycle of farmed fish

In the wild, fish of the same species will grow and reach sexual maturity at different rates, depending on their local conditions. Water chemistry, temperature, food availability, and population size are some of the factors which contribute to this variable growth.

For commercial fish farmers, there is considerable incentive to control the growth and sexual development of stock. Upon reaching sexual maturity, fish lose weight and decrease their stores of fat. Because this reduces the value of their stock, many conventional producers seek to influence the course of nature. In addition to growth and sexual development, interventions are applied to restrict the physical damage caused by overcrowding, to prevent disease, and to effect alterations in the colour, texture, and flavour of their farmed seafood. In theory, the capacity to control these factors should help to facilitate the most efficient application of resources. With these efficiencies in place, the anticipated outcome is a standardised fish product which can be promoted to consumers as a dependable source of fresh protein.

The reality of conventional fish farming

When stressed by overcrowding, pollution, or changes in their regular environment, farmed salmon are susceptible to disease and parasitic organisms. Infestations of sea lice (lepeophtheirus salmonis) are very common. They interfere with feeding, lower immunity and eventually break down the mucus layer which provides external protection against bacterial infection. Without treatment, fish usually succumb to a slow and agonising death.

Most conventional fish farms treat serious infestations with organophosphate pesticide. Despite claims to the contrary, these chemicals contaminate a significant proportion of conventionally farmed seafood. They contribute to a combined toxic load which can include polychlorinated biphenyls (PCBs), dioxins, and heavy metals like mercury. Sea lice are less problematic when fish populations are restricted to environmentally sustainable levels. Salmon raised on overcrowded farms may require antibiotics and other medications to control inflammatory tumours which debilitate and kill large numbers of fish every year. Seriously contagious diseases such as infectious anaemia have the potential to wipe out significant stocks of farmed fish. In the United Kingdom, outbreaks of this disease must be reported. Since no effective treatments are currently available, the usual obligation is to destroy the afflicted stocks.

Wild salmon eat a varied diet which is particularly rich in crustaceans. Their natural red colouring comes from the keratin protein of shrimp, crabs, and other shelled creatures. When farmed on a diet of processed fish meal, their flesh becomes pale pink or an unpalatable grey colour. Since consumers expect their salmon to be brightly coloured, most conventional farmers supplement their feed with artificial colouring agents like canthaxanthin and astaxanthin. Some organic farmers use a yeast compound to enhance the colour of their product while others achieve a brighter colour by including crustacean shells in their feed.

Genetic modification

In recent years, several fish species have been genetically modified in efforts to improve their cost efficiency and manageability as commercially farmed stock. The biotechnology scientists have experimented with gene manipulation to alter food conversion efficiency in farmed salmon and trout. They have attempted to increase the fish’s capacity to withstand extreme cold by inserting mammalian growth hormone genes into fertilised fish eggs to encourage accelerated growth and weight gain. These technologies are often widely condemned when applied to conventionally farmed land animals. In the case of fish, many consumers are confused or genuinely surprised to be informed of them. Unless there is an adequate evaluation of the health and environmental consequences of these technologies, consumers are advised to avoid them. The alternative is to obtain unaltered seafood captured from the wild, or to consider farmed products with an organic certification.