Production Systems
All king salmon farmed in New Zealand are born in land-based hatcheries, then transferred to sea cages or fresh water farms, where they are grown to harvest size.
Most on-growing of salmon in New Zealand occurs in sea cages in the Marlborough Sounds, Stewart Island and Akaroa Harbour. There are, however, some freshwater grow-out operations in the Canterbury, Otago and Tasman regions. These freshwater farms are usually ponds and raceways, but can also be in nets suspended in hydro canals.
Grow-out operations in sea cages grow their salmon to harvest size in netting cages that are each around 18,000 cubic metres in size. A whole grow-out farm usually covers up to 1.5 hectares.
There are several land-based hatcheries around New Zealand that supply young salmon to grow-out farms.
New Zealand salmon farms use diets specially formulated for king salmon. These feeds do not contain antibiotics, vaccines, steroids or other growth enhancers.
Sea-based grow-out salmon farms tend to be placed in areas that are ‘flushed’ by currents. This improves the rearing environment for salmon and minimises the effects of salmon waste and uneaten food on the environment. These effects can be further reduced through farm management practices – particularly around stocking densities and feeding.
The relative absence of salmon diseases and parasites in New Zealand waters means chemical treatments against these things are not used in New Zealand salmon farms.
Salmon generally reach a harvestable size of 3-4kg live weight after 10-18 months in seawater.
A number of New Zealand salmon farming operations anaesthetise salmon before slaughter using Aqui-S™ - an organically based anaesthetic developed in New Zealand that is safe for use in food and which has been favourably reported on by the British Humane Slaughter Association.
King salmon are farmed in the following New Zealand regions:
Source of Stock
Broodstock used in most New Zealand marine salmon farms is selected from farm stock. Some New Zealand freshwater salmon farms use broodstock returning from the wild.
Eggs and milt are manually stripped from mature ripe salmon and incubated in a hatchery under conditions that replicate those found in streams and rivers where salmon would naturally spawn.
The fertilised eggs hatch into baby salmon (alevin) which are generally reared in the hatchery until they reach the smolt stage of development (about 6 months). At this point they can be transferred to sea cages for on-growing (the smolt stage is when young salmon naturally swim down the river to the sea).
Salmon for freshwater farms can be transferred there as fry before they reach the smolt stage.
Stocking Densities
Stocking densities in sea cage salmon farms tend to range between less than 1 kg m-3 up to around 25 kg m-3, depending on the life stage of the salmon being farmed.
Growing and Harvesting
All king salmon farmed in New Zealand are born in land-based hatcheries, then transferred to sea cages or fresh water farms, where they are grown to harvest size.
Most on-growing of salmon in New Zealand occurs in sea cages in the Marlborough Sounds, Stewart Island and Akaroa Harbour. There are some freshwater grow-out operations in the Canterbury, Otago and Tasman regions. These freshwater farms are usually ponds and raceways, but can also be in nets suspended in hydro canals.
There are several land-based hatcheries around New Zealand that supply young salmon to the farms, where they are grown on to harvestable size.
On the farms, salmon are fed an artificial diet, high in protein and fat. Typical proportions of the feed are protein 45.2%, fat 21.5%, carbohydrate 14.2%, ash 9.8% and moisture 9.3%, with vitamins and minerals added to provide a balanced nutritious diet.
The New Zealand Salmon Farmers Association’s Finfish Aquaculture Environmental Code of Practice states that raw material for fish feeds should come from sustainably managed fisheries.
The standard feed on New Zealand farms does not contain antibiotics, vaccines, steroids or other growth enhancers.
The relative absence of salmon diseases and parasites in New Zealand waters means chemical treatments against these things are not used in New Zealand salmon farms.
Salmon generally reach a harvestable size of 3-4kg after about 10-18 months in seawater.
A number of New Zealand salmon farming operations anaesthetise salmon before slaughter using Aqui-S™ - an organically based anaesthetic developed in New Zealand that is safe for use in food and which has been favourably reported on by the British Humane Slaughter Association.
Additives and Treatments
Salmon Feed
New Zealand salmon farms use diets specially formulated for king salmon. The standard feed on New Zealand farms does not contain antibiotics, vaccines, steroids or other growth enhancers.
The feed contains very small amounts of zinc (concentrations of ~130 - 150 mg/kg, or 0.013-0.015%), which is an essential micronutrient for the prevention of cataract formation and other health problems. Zinc has been known to accumulate in sediments beneath fish farms in New Zealand and internationally (refer Ecological Effects: Chemicals and Additives section). Feed companies are presently investigating ways of minimising zinc discharges to the seabed, primarily by reducing the content in the feed.
The New Zealand Salmon Farmers Association’s Finfish Aquaculture Environmental Code of Practice states that raw material for fish feeds should come from sustainably managed fisheries.
Chemical Treatments
The relative absence of salmon diseases and parasites in New Zealand waters means chemical treatments against these things are not used in New Zealand salmon farms.
