Farmed fish

Last updated 25 September 2020

According to the United Nations, in 2018 the raising of underwater, factory-farmed fish was at a record high with 114.5 million tonnes of live weight produced, accounting for 53% of fish products produced - the farmgate value of which is a staggering 263.6 billion USD. 

(a) Is a health Atlantic salmon (b) A growth stuned 'drop out' salmon. Photo by Ole Folkedal

Fish raised in underwater fish farms have been observed to exhibit brain activity akin to that of humans under extreme stress and depression.

Research suggests stunted growth in farmed fish is a strong indication of their emotional state.

 

Breeding

Breeder fish, known as broodfish have their milt (eggs and sperm) collected in a hatchery. Female fish are sliced open and their eggs are scooped out from inside of them, in a process commonly referred to as ‘milking’. Sperm is squeezed out of male fish to combine with the females’ eggs.

Some females are said to be able to ‘recover’ from this process, however all males die. The eggs are incubated until the fry (baby fish) are actively feeding and then they are moved to rearing tanks or cages. 

 

Hatchery 

Farmed fish are bred indoors in hatcheries. As fish grow, they are moved to various tanks inside the hatchery facility. As an example, farmed salmon spend 10 to 16 months of their lives in on-land tanks.

Whether fish are a freshwater or saltwater breed largely dictates the way in which they are farmed.

Image: Atlantic salmon being subjected to 'milking'. Source: Canberra Times.

 

Cages and tanks

Freshwater fish, such as barramundi, will spend their entire lives - years - in either indoor tanks or outdoor pens. 

Other breeds, like salmon, are pushed through pipes and into tanks which take them out to caged sections of the sea where they will spend another 14 to 18 months before they are killed. In the underwater cages, salmon are crammed in with thousands of others, unable to live as they would in the wild.

Many species of fish will naturally swim thousands of kilometres throughout their lives, and still, in supposedly ‘high welfare’ Tasmanian fish farms the circumference of underwater cages is a mere 240 metres.

 

The health of fish raised in ocean and on-land factory farms is severely impacted by the way in which they are housed. Living in such close confines with other fish means diseases spread rapidly. Amoebic gill is a common gill disorder found in salmon, caused by a parasite that thrives in warmer water, which is of particular concern during Australian summers. Characterised by deteriorated gills and difficulty breathing, the disorder can lead to heart collapse and death.

These diseases can also spread to wild fish populations, causing even more suffering and death as well as contributing to the ever-approaching reality that we could face fishless oceans by the year 2050. In 2018, over 1 million fish were killed by a virus on Tasmanian fish farms.  

 

Sea Shepherd Conservation Society

In some cases, health issues for farmed fish such as sea lice and amoebic gill disease are treated with ‘sea baths’ which involves fish being forced through tubes into freshwater tanks before being pushed back into their sea cage. During summer these baths can occur as frequently as every 30-40 days; being put through this process causes high levels of stress. This process is also dangerous, with hundreds of thousands of fish having died during, the cause often being ‘human error’.

Slaughter

The most common method used to kill fish is by asphyxiation, which is slow, agonising, suffocation. One study found that across a range of different species, 55-250 minutes passed before fish were insensate in the case of asphyxiation. This means fish suffered and continued trying to breathe for a staggering 4 hours. Sometimes an ‘icy-slurry’ is used during this process, however fish can still take as long as half an hour to die. [note]

Some farms who profess to be ‘higher welfare’ use stunning methods to render fish unconscious by:

  • ‘Percussive stunning’, a form of blunt force trauma, where the skull is smashed with a heavy blow that hits the brain.
  • ‘Electrical stunning’, where fish are put in electrified water. 

Following this, fish are bled out and gutted.