Why is salmon pink?

The colour of a salmon’s flesh, whether wild or farmed, is determined by its diet. Ranging from orange to ivory-pink, flesh coloration is a result of the levels of organic pigments, known as carotenoids, present in what the fish has eaten.

There are more than 600 naturally occurring carotenoids; they are what make carrots and pumpkins orange, daffodils and sweetcorn yellow and what produces the spectacular colour changes in autumn leaves.

For animals such as pink flamingos and through to the vibrant red sockeye salmon, which feed on crustaceans and plankton, the carotenoid responsible for their eye-catching colours is called Astaxanthin.

Astaxanthin, which can be synthesised or biologically grown, is a powerful antioxidant and source of pro-vitamin A. These properties stimulate immune systems and can improve fertility and growth. In Scotland farmers use a organic, naturally sourced pigment, derived from the fermentation of a micro-organism and with no additives or preservatives.

Light pink flesh of a salmon smolt without carotenoids present in diet

Scottish Salmon farmers want to provide their fish with the best feed possible, closely aligned to a wild diet, but they also want to meet the expectations of consumers. The salmon farming sector therefore adds small quantities of Astaxanthin (between 20 and 60 milligrams per kilo of food) to salmon feed resulting in not only healthier fish but also the familiar ‘salmon pink’ colour of fillets.

What would salmon flesh look like if this important pigment was left out of their diets? As the picture above (of a salmon smolt fed a non-carotenoid diet) shows it would look much more like haddock, white with a pink hue.

Pale flesh of a white Pacific Chinook or King salmon

In the wild, 1 in 20 Chinook (also known as King) salmon, found in the northwest Pacific, is unable to process Astaxanthin which results in its flesh staying white. Until recently the white-fleshed chinook salmon was considered less desirable.

What is emamectin benzoate? SSPO Admin 07/01/2020

What is it?

Emamectin benzoate is the active ingredient in a veterinary medicine, prescribed to treat sea lice. It is a an avermectin, one of a series of drugs used to treat parasites. Emamectin benzoate is used in agricultural settings to control insects among vegetable crops such as cabbage and broccoli.

Why is it used?

What is Deltamethrin? SSPO Admin 07/01/2020

What is it?

Deltamethrin is the active ingredient in a veterinary medicine, prescribed to treat sea lice. It is a synthetic pyrethroid which mimics natural chemicals produced in certain chrysanthemum flowers. In agriculture it is used in the control of ticks and is also one of the primary ingredients found in household ant powders.

Why is it used?

What are sea lice? SSPO Admin 07/01/2020

Sea lice are naturally occurring ectoparasitic copepods which can affect both wild and farmed fish populations. They are tiny, translucent fish parasites and do not affect humans. How planktonic stages of sea lice disperse and find new hosts is still not completely known but sea temperature, light, and currents are all major factors.

What is Azamethiphos? SSPO Admin 07/01/2020

What is it?

Azamethiphos is the active ingredient in Salmosan, a veterinary medicine prescribed by fish vets to treat sea lice.

Why is is used?

Sea lice are naturally occurring ectoparasites that can cause harm to fish. In order for the Scottish salmon sector to maintain the highest standards of fish health and welfare it is necessary to use medicines alongside a selection of alternative management measures (Figure 1).

How do acoustic deterrent devices work? admin_sspo 03/12/2019

The first acoustic deterrent devices (ADDs) were developed several decades ago, and were basic, if imaginative: farmers used underwater speakers to play recordings of killer whales (orcas), a natural predator of seals. However, the latter quickly caught on and the deterrent effect was short-lived.

Modern ADDs use underwater transducers (a device that turns one form of energy into another – in this case, electrical energy into sound). The deterrent, which creates a temporary sonic fence around a salmon farm can work in two ways:

Salmon mortality: what are the causes? admin_sspo 03/12/2019

Fish health and welfare are at the heart of successful Scottish salmon farming. It is in everyone’s interests to operate to the highest of welfare standards.

The reproductive strategy of fish is to produce a large number of offspring so that a proportion will survive to adulthood. 

Fish, including farmed fish, are subject to a number of pressures in the environment, particularly naturally present pathogens. It can, therefore, be expected that some fish will experience challenges to their health. 

Why is hydrogen peroxide used by salmon farmers admin_sspo 03/11/2019

What is hydrogen peroxide?

Hydrogen peroxide is water with an extra oxygen molecule. It is a naturally occurring substance found in the atmosphere, soil and water, and is naturally produced by many living organisms including humans in breast milk. It also has many commercial applications including, sterilisation of juice and milk cartons, hair and teeth bleaching and as a disinfectant for contact lenses.

Why is hydrogen peroxide used in salmon farming?

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