By Asbjørn Bergheim*
Arctic charr is the most cold-water adapted salmonid species, with both landlocked and anadromous populations. Artificial breeding was initiated in North America and Europe in the late 1800’s (Sten Siikavoupio, personal communication). Naturally, the species grows well at a low temperature of 6 – 10ºC. Most important for intensive aquaculture, Arctic charr is a schooling fish and tolerant to high-density conditions. No growth decline has been reported at stocking levels as high as 100 kg/m3 provided that water quality is controlled. Cold-water species are vulnerable to oxygen deficits, and in tanks stocked with charr the running concentration should be kept above 70 – 80% of saturation.
Exact figures of Arctic charr production are not available, but the annually produced volume some five years ago was roughly 3,200 tons in Iceland, 2,300 tons in Sweden and 700 tons in Norway (Bjørn Sæther, personal communication). The Canadian production was a bit below 1,000 tons at the turn of the millennium.
Aquaculture of charr has faced some problems, such as temporary disease problems (BKD in Iceland) and marginal profitability. Consequently, the global production has not increased much in recent years.
Iceland is the major producer of charr and most farms are land-based, supplied with ground water. Some farms also use geothermal water to control temperature at optimal level for growth (www.fisheries.is/aquaculture/species/arctic-charr/). The world’s biggest farms belong to Islandsbleikja and Samherji located outside Reykjavik where three sites produce a total of about 3,000 tons of charr per year from eggs to harvest size (see picture of on-growing in large tanks). About 90% of these farms’ total production is exported to the U.S.
The majority of the Swedish production takes place in freshwater cages in reservoirs for hydroelectric power production. The on-growing in the cages is based on stocking of juveniles from tank-based onshore hatcheries. According to Swedish studies, Arctic charr tends to prefer a temperature of 11ºC in cages and thus it is found advantageous to use deep cages allowing the fish stock to select this temperature during summer and autumn. Only two out of the 17 operating Norwegian farms produce Arctic charr in seawater cages but these two farms represent about 2/3 parts of the country’s total production (Bjørn Sæther, personal communication).
Scottish and Scandinavian fjords, where freshwater run-off leads to reduced salinity and where the winter temperature beneath the surface layer remains around 6 – 8ºC, are considered to be suitable for mariculture of charr. So far, however, these sites are predominated by cage farming of salmon.
A selective breeding program was carried out for charr in Sweden (Lars-Ove Eriksson, personal communication) and has demonstrated a remarkably improved performance. Over two decades, the growing cycle was halved, the individual size at maturation has increased, etc., all resulting in strongly reduced production costs.
Arctic charr is considered a very high quality product with a delicate texture, mild taste and pink-orange colour (www.fishchoice.com). The low production volume makes charr not widely available, and consequently it is a high price product. Charr is commonly sold as boneless fillets or fresh whole fish.
Processing of charr fillets in an Icelandic factory illustrates the delicious product before packing and export to the market.
Dr. AsbjØrn Bergheim is a senior researcher in the Dept. of Marine Environment at the International Research Institute of Stavanger. His fields of interest within aquaculture are primarily water quality vs. technology and management in tanks, cages and ponds, among others.