Recirculating aquaculture systems (RAS) are helping the salmon farming industry maintain positive production amid growing biological challenges in sea pen production, according to the latest edition of Spheric Research's Land-based Aquaculture Report.

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Land-based Aquaculture Report 2024 (Fourth Edition)

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The report closely analyzes over 200 RAS post-smolt facilities globally. It finds that major salmon producers like Norway and the Faroe Islands have insulated themselves from declining production thanks to their widespread embrace of land-based RAS technology over the last 10 years.

Norwegian aquaculture leaders Mowi and SalMar have especially prioritized investing capital into large-scale RAS smolt and post-smolt farms to supply their ocean net pen operations. The report shows a strong correlation between RAS adoption levels and protection against slowed expansion numbers.

While aquaculture scientists are still debating whether RAS produces healthier post-smolts, there is broad consensus that minimizing grow-out time in the sea reduces fish mortality. Scientists cite rising temperatures, frequent sea lice infestations, and other climate change impacts as growing threats. 

The Faroe Islands and Norway are the only major salmon-producing countries to expand production growth in the past five years, with overall declines from Chile, the UK, and North America. The two Scandinavian countries have overwhelmingly invested in growing larger smolt to shorten sea pen cycles.  

Grieg Seafood said its mortality rates in Rogaland, an area of southern Norway that has suffered frequent sea lice outbreaks, dropped to 8.3% in an experiment using 1-kilogram post-smolt. The average mortality rate in the region is 19%.

Survival rates increase when salmon are harvested before they spend a second summer in the sea, when they are at greater risk of dying, Bakkafrost Scotland managing director Ian Laister has said. The Faroese salmon giant is investing heavily in post-smolt capacity to improve fish health and performance at its Scottish operations.

Traditional smolt weighing 100g have to spend 11-13 months in the sea in Chile to reach harvest weight, according to producer Multi X. That time falls to between nine and 11 months for 460g post-smolt and seven to nine months for 850g fish.

Larger post-smolts also don't need to be deloused as frequently as 100g smolts, a size that used to be the industry norm. Conventionally sized smolt can receive as many as five treatments before harvesting in modern times. According to a study by Trond Bjorndal and Amalie Tusvik of the Norwegian University of Science and Technology, each de-lousing treatment cycle results in lost feeding days and higher mortality. 

The Faroe Islands and Chile were early adopters of RAS technology to grow smolt. Faroese producers started to use the technology in the 1990s, with producer Hiddenfjord claiming to be the first to raise a larger smolt in 2010. The first RAS smolt facility in Chile opened in 2001 to circumvent freshwater shortages. Norwegian farmers weren't even allowed to grow post-smolt beyond 250g until a law took effect in 2012.

The average weight of Faroese post-smolt stocked in net pens exceeded 400g in 2020, compared to 180-200g smolt in Norway, according to Faroese analytics firm Avrik. Chile's average smolt release size rose 1.5% a year to 167g from 2016 to 2023, according to Aquabench, another industry benchmarking firm.

Spheric Research has categorized RAS smolt units as starter smolt or post-smolt systems. It calculated the average installed RAS post-smolt capacity as a percentage of overall production for major producing regions and countries. The Faroe Islands enjoys a significant lead over runner-up Norway, with a post-smolt capacity of 10% for the country's estimated 2024 production of 93,000 metric tons.

Norway's RAS post-smolt capacity has steadily grown to an estimated 4% of this year's projected harvest of 1.34 million metric tons. The ratio of RAS post-smolt capacity to total production in Canada, Chile and the UK is still less than 1%, meaning few producers in those countries are following the trend of building post-smolt systems.

Producers in Canada and Chile have held back on investment amid growing concerns about the growing resolve of anti-salmon farm campaigners in Canada and burdensome regulations in Chile. In Canada, the government is phasing out parts of its net pen industry in the main production province of British Columbia. 

A correlation analysis of the data supports Spheric's theory that significant Faroese and Norwegian investment in RAS post-smolt infrastructure prevented a drop in global salmon production during 2019-24. A correlation coefficient of 1 means there is a perfect positive relationship between two variables, while a coefficient of 0 means there is no correlation; the Faroe Islands had a correlation coefficient of 0.75 and Norway 0.64 for the five-year period.

Only one in five smolts released in Norway in 2022 were post-smolts. In countries like Canada and Chile, where regulations limit RAS smolt investment, that number is even lower. With the right regulatory framework, the potential to increase the productivity of traditional net-pen farms through greater use of post-smolts grown in a RAS system is enormous.