Fish Farming In New Zealand
Fish farming, particularly salmon farming, is big business in New Zealand and is looking to expand considerably. The majority of farmed salmon is produced by salt-water operations in the Marlborough Sounds and Stewart Island. The breed used is Chinook, or king salmon, and is non-native to New Zealand.
The salmon are reared in land-based hatcheries then transferred to sea cages or fresh-water farms. To make them grow fat and fast, salmon are fed a synthetic diet fortified with fishmeal and fish oil. They generally reach slaughter size after 10-18 months. About 50% of New-Zealand-farmed salmon is exported, with Japan and Australia being the biggest markets.
Invasive and dangerous farming methods
The repetitive manipulation in fish farms is a major cause of stress and pain. Salmon need to be constantly sorted by size and separated, as trapped bigger fish will bully smaller fish. Other invasive practices include vaccinations, loading, transportation and breeding techniques in which the male is brutally stripped of sperm and the female of eggs.
Farmed fish are liable to suffer high mortality rates from injury and disease, and they are also vulnerable to predators and other hazards. Attacks from seals are a major issue in New Zealand, and in just one incident in 2009 thousands of fish were killed when jellyfish floated into a salmon farm.
There is a perception that captive fish farming takes the pressure off wild fish populations. Unfortunately the opposite is true. Wild fish are caught and used to feed the farmed fish, which contributes to the threat to the biodiversity of our oceans. Additionally, all waste from factory-farmed fish goes untreated into the sea. Salmon advertising talks about "the pristine waters of the Marlborough Sounds", but as operations become bigger so do the levels of pollution. Waste in the water also encourages the growth of algal bloom, resulting in depleted oxygen levels and poor water quality.
By definition fish farming is not 'sustainable'.