Are medicines/antibiotics used in salmon farming?
Are farmed salmon coloured artificially?
How does Marine Harvest control predators taking its fish?
How are salmon farms working to control sea lice?
Do salmon escape from farms?
Is fish farming causing algal blooms and shellfish poisoning?
Are salmon kept in crowded conditions?
Are medicines/antibiotics used in salmon farming?
As with humans and other animals, both wild and farmed fish are susceptible to attack from infectious pathogens. If left untreated, diseases (viral, bacterial and parasitic) can compromise welfare and cause significant mortalities in a short period of time, so safe and effective control is vital.
In comparison with the number of medicines available and used in terrestrial food animal production, only a limited number of preparations are available to fish farmers to treat disease or to eliminate parasites such as sea lice. These prescription-only medicines are applied under strictly controlled conditions, in line with regulatory authority rules and recommendations, and under the supervision of authorised veterinarians.
Marine Harvest adopts a preventative approach to disease and health management through good husbandry and feeding methods, e.g. fallowing and introducing only healthy stock. Health strategies and good husbandry practices together with vaccination have now greatly reduced diseases.
Antibiotics are not given to promote growth, neither are any growth-promoting hormones used.
Marine Harvest uses good husbandry and management, and safe and efficacious vaccines to minimise the need for medicines and will continue to seek ways of improving these practices. Marine Harvest is actively involved, together with vaccine and pharmaceutical producers and other aquaculture companies, in the development of new vaccines and technologies. Where vaccines are not available, Marine Harvest uses licensed medicines, in accordance with relevant regulations, to control outbreaks of disease.
Any medicines that are used are authorised by the regulatory authorities when they are satisfied that the correct use of the medicines presents no risk to the operator, consumer, fish or the environment.
Authorisation specifies withdrawal periods and tolerance levels for residues, which must be observed prior to harvest. The Maximum Residue Limits for medicines, as specified by the EU, by the FDA in the United States, by the Food Inspection Agency in Canada and by the Japanese Minister of Health, Labour and Welfare among others, are implemented as the minimum requirement. These are equivalent to the conditions that apply to the use of medicines in other food animals.
Are farmed salmon coloured artificially?
The pink colour of salmon flesh, wild or farmed, is caused by the presence of carotenoid pigments. These are known to be important in salmon and human nutrition, since they are important antioxidants.
The wild salmon diet includes krill, zooplankton, small fish and crustaceans. Crustaceans and krill contain carotenoids that are absorbed by the salmon and deposited mainly in the muscle but also in the skin and in the eggs. The intensity of the colour varies between fish and does not seem to have an effect on the taste but it does enhance attractiveness to the consumer. There is evidence to show that there are several health benefits from the pigments for salmon and trout.
There are more than 600 naturally occurring carotenoids and, for example, they produce the colours of carrots and of autumn leaves. The group of carotenoids found in fish are known as xanthophylls and include astaxanthin and canthaxanthin
As salmon are unable to synthesise these pigments, they must take them in as part of their diets. The pigments may come from crustaceans, from yeast culture or, more usually, from nature identical products — all are approved for addition to the diet of farmed salmon and of trout.
Fish health benefit.
In the wild salmon it seems that the pigmentation has benefits in camouflage and in sexual attraction.
As female salmon prepare for breeding, the xanthophylls are transported to the ovaries where they improve the maturation rate of the oocytes. The pigments become part of the yolk sac. When the eggs are released, the pigments have two further functions, protecting the eggs from damage by light and helping the male to find them. Carotenoids in the diet have been shown to increase the growth rate and survival of juvenile fish and are implicated in the synthesis of vitamin A in the fish.
How does Marine Harvest control predators taking its fish?
All animals that are farmed, including fish, have natural predators that will try to take stock from farms.
Marine Harvest acts to protect wildlife and takes a humane approach to animals that naturally prey on its fish throughout their growth cycle. The company policy is to discourage predators by employing a range of accepted and approved preventative measures, such as nets, which achieve a high rate of success while minimising damage to wildlife.
How are salmon farms working to control sea lice?
Sea lice are naturally occurring ectoparasites (ectoparasitic copepods) of salmon and a range of other wild fish species. They occur on both wild and farmed salmon and horizontal infection occurs in both directions.
Through a combination of good husbandry and management techniques together with biological and medicinal control, sea lice infections on Marine Harvest farms are kept to a minimum, for welfare, environmental and economic reasons. As a result, the spread of lice from farmed salmon to wild salmon is minimised.
Sea lice feed on the mucus and skin of the host fish. They are indigenous and were present long before fish farming started. Their presence is maintained through the wild population. When commercial farming began, the health status of the fish became important and it is much easier to monitor than that of the wild population. As a result, we are more aware of impact, biology and control of such pests on farmed fish.
Reducing the problem
Active health monitoring programmes, including regular veterinary inspections, are proving to be a tool in limiting sea lice abundance. The magnitude of the problem is declining through modern husbandry and management practices and the latest biological and medicinal control techniques. These involve a combination of methods and preventative approaches. In areas of Scotland, Norway, Ireland and some areas in Chile, companies have arranged that whole loch/fjord systems be managed in a strategic and coordinated way thus reducing lice abundance and consequently the risk of infection within a body of water.
Medicines
Marine Harvest realises the importance of having safe and efficacious medicines available for the control of sea lice. As a major salmon farming company, Marine Harvest provides open and unlimited technical support for the maintenance of existing products in each market and for the development of new products and technologies that will further improve lice control strategies.
In addition, Marine Harvest is committed to efforts to limit discharge of medicines into the environment and maintaining environmental standards for sea lice medicines.
Biological control
On farms in Scotland, Norway, Shetland and Ireland, indigenous cleaner fish, specifically wrasse, can be used to clean the lice from the salmon. These fish are sourced locally from sustainable fish stocks. Also, sites are left fallow (unoccupied and inactive) for several weeks. Without hosts, the lice population dies out. Both wrasse and fallowing are biological control methods.
Integrated pest management
Marine Harvest has put into place an internal procedure for Integrated Pest Management (IPM) and Resistance Management (RM) strategies. This follows a two-year internal development project. The procedure was designed to be compatible with and adaptable to the various national guidelines and programmes such as Norway’s Nasjonal Handlingsplan mot lus på Laksefisk (National Action Plan for Combating Sea Lice in Salmon Farming) and Chile’s Caligus Plan.
IPM and RM seek to incorporate good husbandry and management practices, to use biological controls and to optimise the use of medicines, including strategically timed and coordinated treatments. This provides efficacious control of lice while maximising the effectiveness of available medicines and prolonging their useful market life. At the same time it reduces environmental inputs and contributes towards a sustainable fish production system.
The concepts of IPM and RM are formally promoted in several aquaculture areas where Marine Harvest is farming, including Scotland, Ireland, Norway, west coast Canada and Chile.
Multi-party projects
Marine Harvest has been an active partner in several projects related to sea lice and their control, where new tools and processes have emerged, and which have been utilised and harmonised to optimise strategic lice control. These projects have included investigations into sea lice epidemiology, sea lice resistance, optimal use of wrasse and the interaction of lice between wild and farmed fish.
Do salmon escape from farms?
Escapes from salmon farms do happen. It is a very small percentage of the total number of salmon in farms but the numbers can seem potentially significant.
Obviously escapes are not to the advantage of the salmon farmer. The economic disadvantage and the wish to produce salmon on a sustainable basis encourage the farmer to use all available precautions to prevent escapes.
Marine Harvest has a zero escapes policy and great attention is being given to ways of limiting escapes. Research confirms that most escapes happen during handling and moving of nets. Extreme weather conditions have also led to escapes and work continues to develop more robust equipment. Another source of escapes can be attack by predators such as seals that can damage the nets allowing fish to escape. In some incidents, escapes were caused by deliberate vandalism.
There is a continuous programme to reduce escapes, including ensuring nets are always in good condition, moorings are renewed on a regular basis, pens are regularly inspected for wear and tear, and nets are weighted properly.
Is fish farming causing algal blooms and shellfish poisoning?
Links are often suggested between the presence of fish farms, the occurrence of algal blooms and subsequent potential for shellfish poisoning. There is no scientific evidence that the nitrogen introduced to the aquatic environment by salmon farms is the cause of these blooms. Algal blooms are natural phenomena, which have been linked to rising sea temperatures.
Shellfish poisoning is caused by toxins that are generated during the algal bloom and then accumulate in bivalve shellfish such as scallops as they filter the water.
Algal blooms can also cause problems to fish. Some species may produce potent toxins such as neurotoxins, others physically clog the gills, leading to damage and in some cases to death by asphyxiation (suffocation). The algae can also reduce the available oxygen in the water.
The toxins concerned and all three forms of shellfish poisoning they can cause; amnesic, diarrhoeic and paralytic, have been known as long as man has been eating shellfish. The algal species concerned have been identified in fossil records. Not eating shellfish in the summer months and purging in clean water have been standard practices for many decades.
Are salmon kept in crowded conditions?
Marine Harvest sees no conflict between commercial interests and taking a humane and enlightened approach to salmon production.
The health of salmon and other farmed fish demands a pure and stable environment, a balanced and healthy diet and freedom from stress. There is a direct link between the standards of husbandry and the high quality products that consumers demand.
Keeping farmed fish in overcrowded conditions would be counter-productive even if the company had no interest in animal welfare. In fact, Marine Harvest holds animal welfare to be an important consideration in all its activities.
The actual stocking density on a Marine Harvest salmon farm compares favourably with other livestock production systems, partly because it is three-dimensional — with the fish able to move vertically as well as horizontally.
Marine Harvest specified stocking densities are around 15–25 kg per cubic metre (1,000 kg of water). This means that even at maximum stocking rates the fish occupy less than 3% of the cage volume and have more than 97% of the space for free movement. Although they have this space available, the fish often congregate and swim together, as a shoal.