Agriculture and Environment: Salmon

Better Management Practices: Fish Oil & Fish Meal

Considerable work has been done to achieve truly phenomenal results in improving the feed conversion ratios for salmon production.

The industry norm at this time is nearly one-to-one: 1 kilogram of feed produces 1 kilogram of product.


Work still needs to be done, however, to change the formulation of the feed to reduce the total quantities of wild fish needed to supply the oil and meal. Today, it takes 4 or 5 kilograms of wild fish to make 1 kilogram of farmed salmon.

In order to reduce overall environmental impacts and use resources more efficiently, this proportion needs to be changed. Given that salmon are carnivorous, it is not clear how much progress can be made.

Vegetable-based oils in place of fish oils
Replacing part of the fish oil component of fish feed with vegetable-based oils would be a good start and could have a number of benefits. It could decrease the toxins from fish oil that farmed salmon currently consume.

Ultimately, this means that humans would consume fewer of these harmful toxins as well. While the accumulation of residues from vegetable-based oils is possible, it is much less of a problem than from fish oil (Jacobs et al. 2002).

The use of fish meal and fish oil in salmon diets has also been linked to eutrophication and pollution problems. A vegetable-based diet results in lower levels of pollution, even though there is still considerable organic matter. Because salmon raised on a vegetable-based diet have a different flavour, a lot of work will need to be done to maintain the flavour profile consumers have come to expect (Staniford 2002).

Alitec, a leading Chilean feed producer, says that it will begin to reformulate its feed so that it will contain significant quantities of vegetable oil by 2004, thus reducing the amount of fish oil used. Though some salmon farmers are sceptical, the company believes that the reformulation will have benefits, one of which will be a lower-priced feed.

Credits

Extracts from "World Agriculture & Environment" by Jason Clay - buy the book online from Island Press

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