Organic waste in farming of salmon 147
hatcheries, the grow- out phase in salt water and the final processing at
slaughterhouses. The hatcheries acquire fertilised eggs, which are hatched
after a period in tempered freshwater. The fingerlings are kept in closed tanks
until they smoltify and are ready for further growth in saltwater.
1
This usually
takes place when the fish (named smolt) are 80–100 g. After vaccination,
well- boats transfer the smolt to grow- out farms – floating cages at sea – and
the salmon remain there until they reach a weight of 4–5 kg. Thereafter, the
mature salmon are transferred to processing facilities where they are slaughtered. The whole production cycle takes three to four years.
The environmental impact of this type of production is threefold. First,
organic waste can have a negative impact on the environment. While the
severity of impact on the eco- system will depend on the specific local conditions of the farm, the nitrogen and the phosphorus in the waste create algae
blooms and anoxic conditions in the coastal water, which can kill other
aquatic life (Wu, 1995). Second, the crowded nets attract sea lice, a parasite
that costs the industry up to 1.5 billion C per year (Costello, 2009). The
Norwegian industry suffered a 5% loss in harvest quality (versus 2015) and a
mortality rate of 19%, up from 16% in 2015, corresponding to 53 million
individual fish (Ernst & Young, 2018). This has resulted in higher operational
expenses in the industry and the introduction of new regulations by the Norwegian government (Ernst & Young, 2018). Chemical mitigation of sea lice
is expensive and inefficient, causing additional adverse environmental impacts
to coastal zones and becoming ineffectual with overuse (Burridge, Weis,
Cabello, Pizarro & Bostick, 2010; Grant, 2002). Third, escaped fish can have
large ecological impacts. Inter- breeding between wild and more genetically
homogenous farmed salmon has been shown to reduce the life and fitness of
indigenous fish populations over two generations (Thorstad et al., 2008).
Therefore, several alternatives to the traditional schedule (one year in landbased freshwater hatcheries; two years in sea- based cages in saltwater) are
being considered, with the aim of shortening the period in the sea. One
alternative is fully land- based production; another is moving the farm to offshore locations. These two options represent large operational, biological and
technological changes, and substantial investments, with high risk. Other
alternatives the industry is considering are closed underwater tanks, or floating basins in the grow- out phase. Currently, the majority of the salmon producers in Norway are using a production line with an extended land phase.
This means that the smolts are not released to the sea at the standard size at
80–100 g, but rather held in the closed surroundings in the hatcheries until
they reach a weight of more than 250 g.
2
In the short term, an extended landbased phase is the most realistic alternative to the traditional production
schedule. Innovations and technological improvements for this alternative have
become prevalent in recent years. For example, the two Danish firms are completely land- based, and Denmark is leading the innovation in this area.
This reorganisation of the production strategy and connected operational
activities will lead to two major changes. First, it will require large
hatcheries, the grow- out phase in salt water and the final processing at
slaughterhouses. The hatcheries acquire fertilised eggs, which are hatched
after a period in tempered freshwater. The fingerlings are kept in closed tanks
until they smoltify and are ready for further growth in saltwater.
1
This usually
takes place when the fish (named smolt) are 80–100 g. After vaccination,
well- boats transfer the smolt to grow- out farms – floating cages at sea – and
the salmon remain there until they reach a weight of 4–5 kg. Thereafter, the
mature salmon are transferred to processing facilities where they are slaughtered. The whole production cycle takes three to four years.
The environmental impact of this type of production is threefold. First,
organic waste can have a negative impact on the environment. While the
severity of impact on the eco- system will depend on the specific local conditions of the farm, the nitrogen and the phosphorus in the waste create algae
blooms and anoxic conditions in the coastal water, which can kill other
aquatic life (Wu, 1995). Second, the crowded nets attract sea lice, a parasite
that costs the industry up to 1.5 billion C per year (Costello, 2009). The
Norwegian industry suffered a 5% loss in harvest quality (versus 2015) and a
mortality rate of 19%, up from 16% in 2015, corresponding to 53 million
individual fish (Ernst & Young, 2018). This has resulted in higher operational
expenses in the industry and the introduction of new regulations by the Norwegian government (Ernst & Young, 2018). Chemical mitigation of sea lice
is expensive and inefficient, causing additional adverse environmental impacts
to coastal zones and becoming ineffectual with overuse (Burridge, Weis,
Cabello, Pizarro & Bostick, 2010; Grant, 2002). Third, escaped fish can have
large ecological impacts. Inter- breeding between wild and more genetically
homogenous farmed salmon has been shown to reduce the life and fitness of
indigenous fish populations over two generations (Thorstad et al., 2008).
Therefore, several alternatives to the traditional schedule (one year in landbased freshwater hatcheries; two years in sea- based cages in saltwater) are
being considered, with the aim of shortening the period in the sea. One
alternative is fully land- based production; another is moving the farm to offshore locations. These two options represent large operational, biological and
technological changes, and substantial investments, with high risk. Other
alternatives the industry is considering are closed underwater tanks, or floating basins in the grow- out phase. Currently, the majority of the salmon producers in Norway are using a production line with an extended land phase.
This means that the smolts are not released to the sea at the standard size at
80–100 g, but rather held in the closed surroundings in the hatcheries until
they reach a weight of more than 250 g.
2
In the short term, an extended landbased phase is the most realistic alternative to the traditional production
schedule. Innovations and technological improvements for this alternative have
become prevalent in recent years. For example, the two Danish firms are completely land- based, and Denmark is leading the innovation in this area.
This reorganisation of the production strategy and connected operational
activities will lead to two major changes. First, it will require large