Background

The Norwegian coast is well suited for aquaculture, offering extensive archipelagos with deep, well flushed inshore fish farming localities and stable salinity and water temperatures. The Norwegian aquaculture industry has prospered under these conditions for many years. Salmonid aquaculture is a major coastal activity in Norway with a current annual production of approximately 1.1 million tons with a value of 3.8 billion Euros. Provided crucial environmental issues can be resolved, aquaculture will expand, with annual growth forecasted at about 4 % and a production of 5 million tons by 2050 is predicted (Anon 2012). 

 With the rapid expansion, the Salmonid aquaculture industry has continuously restructured since 1999, with reductions in the number of farms (1900-1000), increased farm size and relocation of farms to deeper (50 - 300 m) and more current rich sites. During this time period, the production has doubled (Gullestad et al. 2011). A typical salmon farm produces between 3-5000 tons in an 18-month period in sheltered coastal waters, but at more dynamic coastal sites, farms may produce as much as 14 000 tons. Continued expansion is expected to promote further restructuring of the industry towards larger industrial farms located in highly dynamic regions and new habitats at the outer coast. There will also be a shift towards northern Norway with less competition for space compared to the southern part of Norway. Rising sea water temperatures associated with global climate change will also favour Salmonid farming in mid and northern Norway.   

The Ministry of Fisheries and Coastal Affairs have stated that “the environmental impact of aquaculture must be kept at an acceptable level and be within the assimilative capacity of the area” (Anon 2009a). Since 2005 all Norwegian fish farm sites have been surveyed according to the risk of impact through a national monitoring system for benthic impact of fin-fish aquaculture (the “MOM” monitoring system; Ervik et al. 1997; Hansen et al. 2001; Norwegian Standard NS9410). However, the monitoring is currently limited to soft sediment habitats. The reason for that is scarce knowledge on other benthic habitats such as hard, mixed and sandy bottom habitats, including sensitive habitats, and seaweed and kelp habitats (Holmer 2010). More and more fish farms are now located over hardbottom, and an increasing number of sites are located in the coastal zone, where soft sediment is less prominent. Increasing our basic knowledge on the environmental effects of salmon farming in these habitats will ensure better management and that an environmentally sustainable industry can be attained.