Deaths of diseased farmed salmon reach an all time high

The Scottish Environment Protection Agency (SEPA) has reported a staggering ten million+ premature farmed salmon deaths in 2019.

Not only are these mortality rates higher than any previous documented year (since 2002), but the mortality rates have also risen faster than salmon production over the years.

High mortality rates indicate suffering, as deaths are rarely instantaneous and rather are due to conditions such as disease and sea lice.

It’s an animal welfare crisis.

In light of this welfare crisis, we take a look at the glaring animal welfare issues on Scotland’s salmon farms.

Disease

Farmed salmon can suffer from a wide range of diseases, given that they are kept in such crowded conditions. High levels of stress in the salmon, caused from sea lice infestations (and its treatment), handling and crowding, mean that they are also increasingly susceptible to infection.

One disease, in particular, Amoebic Gill Disease (AGD)- which causes respiratory problems, and can cause death through asphyxiation- is still a major cause of mortalities in Scotland and has been known to cause up to 50% of losses on salmon farms.

There have been countless incidences of diseases causing havoc on Scottish fish farms. In 2019, the £3 billion fish farming firm, Mowi, reported the deaths of around 700,000 salmon on its farms in just a three month period. Diseases and sea lice infestations were among the top reasons cited for the huge numbers of deaths.

Sea lice infestations 

Sea lice infestations are rife on Scotland’s salmon farms.

Sea lice feed on the skin, scales, tissues and mucous layer of salmon, causing the development of lesions and loss of scales and ultimately even death. So – called “death crowns” can also be created by sea lice, whereby the flesh on the head of the fish is exposed. For example, Fish Health Inspectorate reports (2017) document seeing fish with “severe lice damage to their heads”.

Heavy infestation of sea lice also can lead to increased levels of stress in farmed salmon. This chronic stress compromises the welfare of fish by increasing the likelihood of further Infection.

Treatment for disease and sea lice infestations

Treatments for sea lice and disease often do more harm than good, exposing salmon to harsh chemicals or harsh mechanical treatments, causing stress, physical injury and death.

 Cleaner fish

Lumpfish, known as “cleaner fish”, are used to pick off and eat sea lice from salmon. As noted by the Farm Animal Welfare Committee (2014a), cleaner fish experience the same welfare issues that farmed fish face

Salmon are also carnivorous, and can show aggression towards cleaner fish, and have been found to consume cleaner fish. Aggressive interactions can also work the other way around, with cleaner fish causing damage to salmon.

In 2019, the Scottish Government’s Animal and Plant Health Agency (APHA) criticised MOWI for failing to protect the welfare of “cleaner fish” earlier that year.

Thermolicer

The Thermolicer is a mechanical treatment that uses a sudden rise in water temperature to kill sea lice. Salmon are first “crowded” into one area, so that they can be pumped up into the Thermolicer. and then exposed to water of up to 34°C, which is outside of their normal temperature range.

Crowding is recognised as a stressful process and can expose the fish to harsh, abrasive surfaces, which can cause them physical damage, while temperatures above 22.5°C inflict stress upon Atlantic salmon. Furthermore, salmon are not used to rapid temperature changes, which causes additional stress.

Escapes

At the beginning of this year, 74,000 farmed salmon escaped from just ONE salmon farm, situated off Colonsay. Mowi, the company responsible for the disaster, was also responsible for the escape of 48,000 fish in October 2017 and November 2018.

Escaped salmon have compromised welfare. They are not well-adapted to the wild, which means that they likely suffer. Despite this, there is evidence that they can interbreed with wild individuals, which compromises the welfare of wild salmon, as it produces offspring that have reduced fitness.

Scotland’s farmed salmon suffer greatly at the hands of Scotland’s salmon farming industry. Please take a stand for these often forgotten animals and sign our petition calling for a moratorium on the expansion of the salmon farming industry here.