What gives farmed Salmon its colour?
In the wild, salmon eat shrimps and fish that contain a class of pigments called Carotenoids.
All living things require carotenoids in one form or another for proper growth and development.
The wild male salmon use the pigment for skin camouflage and in sexual attraction during the breeding season. While in the female salmon, as they prepare for breeding, the carotenoids are transported to the ovaries where they improve the maturation rate of eggs. The pigments become part of the yolk sac. When the eggs are released, carotenoids have two further functions, protecting the eggs from damage by light and helping the male to find them.
The levels of pigment found in the flesh of both wild and farm raised salmon are essentially the same. The fact that they also give the flesh of the salmon its characteristic pink colour, which we have come to expect from this fish is a by-product, not an end in itself.
Despite these facts some claim the source of the pigments in farmed salmon is un-natural.
However, this is not the case. The pigments used in fish feed are part of a balanced diet designed to be identical to those found in nature.
These pigments don’t just serve as powerful anti-oxidants in our salmon and trout, they make a positive contribution to our health too.
So do we dye our fish? No – there is a pigment in the diet fed to farmed salmon, but the same pigment is in the diet of wild salmon.
How is salmon farmed?
Huon Aquaculture farmed salmon are held in rearing pens that contain just under 99 per cent seawater – that is a stocking density of 12 kilograms per tonne of water – the lowest stocking density in the world.
This means that our Tasmanian salmon live in pens with clean flowing seawater passing through our nets driven by the tide and wind.
It’s difficult to imagine the volume of seawater enclosed and flowing through the nets of even one of the sea pens on a Huon site. On average the salmon inside one of these structures have almost 24,000 cubic metres of water to swim around in.
What is just as important is how the fish use all of this space they have available to them. Salmon form shoals, socially ordered groups in both the farm and in the wild. The fish not the farmer tend to set a shoals density by choosing how close they are to their neighbours.
Salmon leave a lot of empty water around the outside of the shoal as they swim purposefully around the giant sea pen. They are extremely active and athletic animals, swimming day and night facing into the current and constantly shifting position inside the hierarchy of the shoal in behaviour that is identical to the wild.
It has been estimated that a wild salmon will swim more than 13,000 kilometres while she is growing in the ocean. That is the equivalent of crossing the Atlantic Ocean and coming back again. Huon salmon are estimated to swim close to this distance too in our offshore southern wild Tasmanian sites.
This freedom to move and behave naturally within a normal social hierarchy goes way beyond any of the standards set for ‘Free Range’ or ‘Organic’ that are used to describe aspects of the rearing methods for other land farmed animals.
How much organic waste does a salmon farm create?
Unlike warm blooded animals such as humans, salmon are cold blooded marine animals and so the waste produced by their metabolism is very different to that produced by mammals.
The bulk of human and other warm blooded animal faeces are made up of bacteria, mostly of the E-coli type and it is these gut microbes that create odour and pose a contamination risk.
Fish digestion works in a completely different way to this. Fish excretory products pose no danger whatsoever to humans because they do not contain E-coli or any of the other potentially pathogenic bacteria or viruses that are found in human or land farm sewage.
So it is probably wrong to use the word ‘sewage’ in connection with fish farms but having said that salmon farms do produce organic waste, which can have a negative impact on the seabed directly under the cages.
Monitoring of this organic waste in Tasmania is undertaken by the Marine Farming Branch of the State Government’s Department of Primary Industry, Parks, Water and the Environment. All Huon farms are monitored and if there is any detectable impact from our operations within 35 metres of the edge of our lease area then we must stop operations at that pen site.
In addition Huon Aquaculture has the lowest stocking density in the world and we also fallow our pen sites for several months each year, to allow the seabed to revert back to exactly how it was before the farm was there. This is in line with environmental best practice and ensures our farming methods are sustainable.
Are there risks associated with the use of anti-fouling paints which can harm the sea bed?
Huon Aquaculture uses copper containing antifouling paints on all our containment nets. These paints are used widely across the marine environment to prevent undesirable loading of marine structures and vessels such as piers, boat jetties, swimming pontoons and boat hulls by preventing the attachment of seaweeds and some invertebrate animals such as mussels.
At present we adhere to the strict standards set by the Australian Pesticides and Veterinary Medicines Authority(APVMA) to guide our use of antifoulants. However we are also developing innovative technology to both reclaim copper from nets and also clean our nets in situ to allow non-antifouled nets to be used.
Huon Aquaculture along with the majority of leisure and commercial water based industry uses antifouling paints under strict federal government control and we are committed to innovation to minimise the need for antifoulants in the future.
Does Huon use antibiotics?
We put our fish first and are committed to preventative health measures. We produce the highest quality Tasmanian salmon for Australian and International markets and we are proud of our animal husbandry and welfare record. Our improved husbandry and breeding program is eliminating even the occasional use of antibiotics on our production farms – a critical part of the Huon Method. Huon farms have the lowest stocking densities in the world, we maintain clean nets, a healthy environment and work hard to reduce stress, all to ensure healthy fish. Huon’s own selective breeding programme produces fish which are ideally suited to our Tasmanian conditions.
In the past when Huon has had to medicate individual pens it was for short periods of 10 days or less. Even then antibiotics were only used under the strict prescription and supervision of a veterinarian and only in response to specific isolated health issues, as with all livestock reared for food production. In the last three years less than 4% of our fish have needed to be treated with antibiotics, this would have represented 0.05% of the feed fed by Huon.
In keeping with the Australian and New Zealand food safety standards and world’s best practice in aquaculture, any fish treated with antibiotics are not harvested until the antibiotic has cleared their system. So if antibiotics were ever used we made sure that there were no residues in the fish that we harvested.
Looking ahead we are actively supporting and funding vaccine development in co-operation with other farming companies to further help our fish deal with environmental stressors and opportunistic bacteria that can make them unwell.
How much wild fish do you feed your salmon?
A lot of people think that salmon farms feed their stocks minced up wild fish in large volumes – we don’t as it wouldn’t meet their needs.
Our Salmon’s diets are strictly controlled. Fish meal is a concentrated protein powder made from small bony oceanic fish and fish oil, and for each kilogram of salmon, about 1.96 kilograms of wild fish is used.
Tasmania is a unique environment and our fish are truly a special breed, so their diets here have to meet some special requirements in two main areas.
Firstly their diet needs to provide the fish with enough energy to live and thrive; secondly it must supply all the nutrients (proteins, fats, vitamins and minerals) to grow.
After many years of research we have a good understanding of what the relative amounts and balance of each nutrient needs to be in the range of environmental conditions we experience. This generates a specification for our diets for each stage of the salmon’s growth.
There is some flexibility in which ingredients go into the recipe to deliver that specified feed but all ingredients must go through a raft of quality checks before they can be used.
Aside from fishmeal and fish oil, our diets may contain wheat, soya derivatives, corn gluten, meat by-product meal, blood meal and vitamin and mineral supplements very similar to those taken by people.