Atlantic salmon culture began in the 19th century in the UK; in freshwater as a means of stocking waters with parr in order to enhance wild returns for anglers. Sea cage culture was first used in the 1960s in Norway to raise Atlantic salmon to marketable size. The early successes in Norway prompted the development of salmon culture in Scotland. And latterly Ireland, the Faroe Islands, Canada, the North Eastern seaboard of the USA, Chile and Australia (Tasmania). Minor production also occurs in New Zealand, France and Spain. Here, I invite you to join me to learn how to raise Atlantic salmon.
Broodstock are selected from seasite production stocks. And normally moved into freshwater tanks or cages in autumn approximately 2 months prior to stripping.
Eggs are stripped dry, fertilised with milt. Then water hardened and disinfected, prior to laying them down in trays or silo systems. They are “shocked” following eyeing by pouring from one container into another to remove unfertilised eggs.
Hatching takes place in hatchery trays or following transfer to tanks. Alevins are provided with a matting or stony “substrate” to mimic the natural gravel “redd”, and usually maintained in darkened conditions. Incubation of eggs and alevins normally takes place in water at <10 °C. Following yolk sac absorption, alevins will “swim up” in the water column, indicating readiness to first feed. First feeding, using inert feeds, is normally carried out following transfer of late alevins into tanks, although feed may initially be offered in hatchery trays. “Feeding fry” can be grown on in tanks, either using flow-through or various recirculation systems, or subsequently in lake cage systems, through parr stages to smolt.
How salmon is farmed?
Bay management areas
Atlantic fish farmers follow the highest fish health management standards and are dedicated to producing high quality and nutritious food using a bay management area approach (BMA).
This approach separates first, second and third year fish supporting a proven agriculture practice of rotation and growout periods. This system allows farmers to coordinate the health management practises on all farms in that area and helps prevent the spread of disease or parasites.
Pristine seawater is essential for the production of healthy, high quality salmon. Each farm’s location is carefully chosen in areas with the right temperature, water depth and swift currents. The tidal movement flushes out the pens naturally and eliminates waste build up.
Salmon farmers follow strict codes of practice regarding waste management. In addition to using underwater cameras and sensors to avoid overfeeding, farmers use tailored feed to suit the dietary needs of salmon at each life stage and improve feed digestibility – both of which significantly reduce waste. Farms are fallowed regularly and the environment under and around their farms is monitored routinely.
What do farmed salmon eat?
Farmed salmon eat nutrient-dense, dry pellets made from animal, plant and fish proteins of natural origin to include essential vitamins and minerals.
Two important ingredients are fishmeal and fish oil, which ensure salmon contain high levels of omega-3 fatty acids that are good for your heart and mind. Fishmeal and fish oil primarily come from a number of sources including forage fish not eaten by humans.
What makes farmed salmon pink?
Carotenoids – the same natural ingredients found in carrots and egg yolks – are added to their diet to provide the fish with vitamin A and give them their pink colour. No artificial dyes are ever used.
Methods of harvesting vary but fish are generally starved for up to 3 days beforehand. The whole process is carried out with the aim to keep stress to a minimum, thus maximising flesh quality. The fish are crowded in pens using sweep nets and are either pumped from the holding pen alive and transported to the slaughter plant, generally by well boat, or slaughtered on the side of the pens.
Handling and processing
In Scotland, for example, most fish are initially stunned using an automated stunner or a blow to the head. Bleeding is then carried out by cutting the gill arches rapidly and the fish are immersed in iced water. Waste disposal of blood is strictly controlled in order to prevent disease transmission. The fish are then gutted, washed and chilled. Once the flesh temperature reaches approximately 3 °C, the fish are graded and packed on ice. At this stage, whole fish can be frozen for sale as whole frozen salmon or as fresh gutted salmon. However, most fish are filleted and either sold as fresh salmon fillets or set aside for smoking.
The smoking of salmon accounts for over 60 per cent of total salmon use. Many different methods of smoking exist, but to summarize the process, the fillets are salted, and smoked over smouldering wood chips. The product is then trimmed, de-boned and either sliced by hand or machines.
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Video source: Noel’s Farm