Growing fish for a growing World: The Future of Salmon Aquaculture

By Caroline Graham

The North Pacific Anadromous Fish Commission(NPAFC)

Increasingly, national and international government organizations are pointing to aquaculture as a solution (Food and Agriculture Organization 2016).

As wild fisheries decline, or remain stagnant, the global population continues to grow, with greater than nine billion people expected to be living on this planet in 2050, raising serious concerns about global food security (United Nations 2017).

Aquaculture is defined by the Food and AgricultureOrganization (FAO) of the United Nations as:

“The farming of aquatic organisms…farming implies some form of intervention in the rearing process to enhance production, such as regular stocking, feeding, protection from predators, etc. Farming also implies individual or corporate ownership of the stock being cultivated”.

Commonly referred to as fish farming, fish are raised through their entire life cycle and then harvested. Aquaculture includes the rearing of many different aquatic organisms, ranging from molluscs to algae to finfish, and these facilities can take on different forms. In finfish farms, fish are often grown in net pens in the ocean, at least during the later life stages. There are also entirely landbased aquaculture systems, which do not allow farmed fish to interact with the external environment. FAO reports that aquaculture is the fastest growing food production sector globally and now provides over half of the world’s fish for human consumption (Figure 1, FAO 2016).

While wild salmon stocks face an unpredictable future due to climate change, salmonid aquaculture has seen a boom in production, starting from just 12,000 tons in 1980 and growing to over 2.4 million tons in 2011, which is a faster growth rate than overall aquaculture production (Schindler et al. 2008; Asche and Bjørndal 2011). Salmonid aquaculture is now the largest single aquaculture commodity by value, according to the latest report by FAO (2016), with the two largest producers of farmed salmonids being Norway and Chile (Asche et al. 2013).

Farmed Atlantic salmon is the most common species, accounting for over 90% of salmonid aquaculture, followed by rainbow trout, coho, and Chinook salmon (Figure 2).

While salmon aquaculture has seen tremendous growth over the past several decades, it has remained a highly controversial issue. Some praise aquaculture for decreasing dependence on endangered wild fish stocks while supplying a nutritious and affordable source of protein. Others condemn the practice for its potentially harmful impacts on the environment and wild fish populations. Recently, aquaculture has received a fair amount of attention, specifically in Canada and the United States, due to an escapement of thousands of Atlantic salmon from a fish farm in Puget Sound, where Atlantic salmon are an invasive species (Johnson 2017). This was followed by heavy criticism for the aquaculture industry from scientists, Indigenous Peoples, environmental advocacy groups, and the concerned public. One of the major points of concern regarding aquaculture practices, and specifically salmonid aquaculture on a global scale, has to do with the spread of disease/parasites that may occur when many fish are grown in a confined space. This could be a threat to wild populations when fish are raised in ocean net pens where diseases can potentially spread from farmed to wild salmon. The increased prevalence of sea lice over the past 30 years has led to widespread concern and major losses for the industry. Costello (2009) estimated that the global cost of sea lice control in 2006 was over 300 million Euros. Some of the infectious diseases that can affect farmed salmonid species include infectious hematopoietic necrosis virus, furunculosis, bacterial kidney disease, and pancreas disease, among others (Toranzo et al. 2005; Lafferty et al. 2015; Jansen et al. 2017). To further exacerbate the issue, the use of antibiotics to treat some disease outbreaks can lead to increased antibiotic resistance, which may affect both farmed and wild fish, and can also negatively impact human health (Cabello 2006; Shah et al. 2014; Aaen et al. 2015).

Another controversial topic related to salmonid aquaculture is the widespread use of fishmeal and fish oil, harvested from wild fish, to feed carnivorous farmed fish. Most fishmeal and fish oil come from small pelagic fish species, such as anchovies, sardines, mackerel, capelin, and herring, which generally have short life cycles and mature and reproduce quickly (Péron et al. 2010). However, the aquaculture boom can even put a strain on fisheries such as these.

Mass production of fish in net pens has led to problems with nutrient loading and pollution in coastal areas. Some of the waste products and contaminants that can end up in surrounding waters are excess feed, excrement, waste from slaughtering and mortalities, chemicals, insecticides, anti-foulants, and antibiotics (Seymour and Bergheim 1991; Turcios and Papenbrock2014). This presents a number of issues for coastal areas, ranging from oxygen depletion and changing benthic communities to the spread of disease and antibiotic resistance (Mente et al. 2006; Shah et al. 2014).

Finally, escapement of farmed fish from net pens can pose a threat to wild populations. In the case of the San Juan Islands escapement in August of 2017, Atlantic salmon were accidently released into Pacific salmon habitat. Even though Atlantic salmon have historically had trouble colonizing the North Pacific, this introduction of non-native fish can affect native populations without establishing a viable population (Naylor et al. 2005). Escaped farmed fish can compete for habitat and prey, and often have an advantage over wild fish, as they are able to grow more quickly due to selective breeding (Fleming et al. 2000; McGinnity et al. 2003; Jonsson and Jonsson 2006). However, even though farmed fish have been found to grow more quickly than their wild counterparts, they show overall reduced survival compared to wild fish (McGinnity et al. 2003).

Keeping in mind the issues raised by salmonid aquaculture, the question becomes: How can we make informed policy decisions regarding the development of this industry that will ensure net positive outcomes in the environmental, social, and economic dimensions? With a growing global population and increasing demand for fish, aquaculture will continue to expand and have the potential to alter the natural environment by affecting wild fish populations and changing marine/aquatic ecosystems. Despite these drawbacks, fish farming has the potential to provide a solution to issues of global food security by increasing access to a nutritious source of protein. Aquaculture is also economically important to a growing number of coastal communities and estimated to provide between 27 and 56 million jobs globally (Phillips et al. 2016). With all of this in mind, where does the future of aquaculture, particularly salmon aquaculture, lie, and how can we arrive at a place where there are net positive outcomes in the environmental, social, and economic dimensions?

The answer is not simple and will certainly involve further investment into research and technology. The aquaculture industry has made some significant strides over the past several decades in reducing their environmental footprint. There has been a shift away from fishmeal and fish oil towards terrestrial-based feeds, which means less dependence on wild fish stocks to feed carnivorous farmed fish (Shepherd et al. 2017). Furthermore, with regards to disease outbreaks and increased antibiotic resistance, there has been increased research into treatment alternatives, such as vaccines, prebiotics/probiotics, immunostimulants, and genetically modified disease-resistant fish (Wetten et al. 2007; Forabosco et al. 2013; Ringø et al. 2014).

Another proposed solution to some of the environmental issues facing fish farms is the application of Integrated Multi-Trophic Aquaculture (IMTA). The objectiveof IMTA is to rear multiple species in aquaculture pens in order to mitigate some of the pollution issues caused by monoculture fish farms (Neori et al. 2004). For example, on the east coast of Canada, Atlantic salmon, kelp, and blue mussels are all farmed together in aquaculture pens (Troell et al. 2009). The kelp and mussels are able to use the excess nutrients and food provided by the fish waste to grow even faster than they would in the wild (Chopin et al. 2004; Lander et al. 2004).

Although IMTA currently represents only a small portion of overall global aquaculture, it is one method of reducing nutrient inputs into the environment from fish farming and it minimizes the risk of harmful algal blooms and anoxia events (Neori et al. 2004).

To further mitigate the harmful impacts of aquaculture on the environment, some producers are turning to land-based aquaculture facilities known as Recirculating Aquaculture Systems (RAS). In these systems water is partially reused after treatment (Martins et al. 2010). These can be used in areas with limited water availability, can reduce waste discharge, allow for more controlled conditions, and decrease the potential for escapees and the spread of disease to wild fish stocks (Bostock et al. 2010; Badiola et al. 2012). However, it is challenging to constantly maintain appropriate water conditions and the steep startup and operational costs are often cited as the greatest limiting factors (Badiola et al. 2012). Most of these facilities are being built on relatively small scales and therefore are not often very profitable. For example, in British Columbia, the average salmon net pen yields 2,500 to 3,000 metric tons of fish while land based facilities average only 100–200 tons (J. Dunn, pers. comm., October 2017). These systems were originally developed and used mainly for freshwater fish that are less sensitive to poor water quality conditions, however, they are more recently being used for marine fish, like salmon, which has required greater technological innovation (Martins et al. 2010).

One of the most recent and promising strides made by the aquaculture industry is the advancement of offshore aquaculture, also referred to as open ocean aquaculture. While it is not yet well defined, the general consensus is that offshore aquaculture refers to farms situated away from the coastline, in the open ocean, which have more exposure to wind and waves and are less accessible than coastal farms (Bostock et al. 2010). This innovative strategy can take a number of forms, including net cages attached to the seafloor, diver-operated submerged cages, ships, and drifting net systems that can be anchored to existing wind and wave farms, or even abandoned offshore oil rigs (Holmer 2010).

While this strategy is in the testing and development stages, it is thought to have a number of advantages over coastal aquaculture. First, it is expected to reduce the impact of pollution and nutrient loading on coastal areas, since these farms are further from the coast and there is increased water circulation, so the waste can be diffused quickly over a large area (Goldburg and Naylor 2005).

Some have also speculated that better water quality will mean fewer disease outbreaks in these farms, compared to coastal ones (Holmer 2010). Offshore aquaculture also reduces competition with other coastal activities since these farms usually lie kilometers away from the coastline (Bostock et al. 2010). This provides the potential for significant expansion and increased productivity of aquaculture. When combined with other innovative aquaculture techniques, such as terrestrial-based feeds and antibiotic alternatives, offshore aquaculture looks to be a very auspicious step towards environmentally-sound fish farming, but is it?

Of course, this new technology has disadvantages as well. One of these disadvantages is the high initial investment cost. Since these facilities will be remote, making them difficult and costly to reach, there is a need for automated production (Skladany et al. 2007). The technology is new and still under development, meaning that the startup costs are significant. However, with automation of production, labor costs would go down. While this would mean less jobs on fish farms, there would be new jobs available in the technology and construction sectors.

Other disadvantages may include interference with shipping, piracy, entanglement of marine creatures in nets, damage to nets by large predators, and the potential for damage by strong winds, waves, and storms. Unfortunately, since this technology is so new, there is a lack of research regarding the extent to which offshore aquaculture facilities may face these challenges. There are a lot of unknowns, not only due to the novelty of this technology, but also because there is less research on open ocean ecosystems and the organisms that reside there, such as salmon in the high seas. Therefore, while offshore aquaculture is predicted to minimize environmental impacts, there is sparse scientific evidence and there are many unanswered questions.

Despite these questions, the offshore aquaculture industry is forging ahead, most recently being led by a Norwegian company called SalMar. One of the world’s largest producers of farmed salmon, SalMar just installed “Ocean Farm 1” in Frohavet, off the coast of Norway, in 2017. This offshore aquaculture facility is a highlyautomated “full-scale pilot facility for testing, learning, research, and development” (SalMar ASA). The structure is 68 meters high, 110 meters in diameter, and has a total volume of 250,000 cubic meters (SalMar ASA), which is roughly the volume of 100 Olympic-sized swimming pools. SalMar claims that this structure can grow up to 1.5 million salmon for harvest in just 14 months (Hoyle 2017). While there is still a lot of testing and research required, salmon offshore aquaculture is already a reality. Jeremy Dunn, Executive Director of the British Columbia Salmon Farmers Association, says: “Everyone around the world is watching how SalMar’s project is going to go”.

Although SalMar’s project is considered offshore aquaculture, the trial system lies within a few kilometers of the coast and the design is only suitable for water depths of 100 to 300 meters (SalMar ASA). An even newer project, that just received permits for development and construction in September of 2017, is called “Havfarm”, which is a collaboration between Nordlaks and NSK Ship Design in Norway. This farm is intended to be the longest ship in the world (430 m long, 54 m wide), and is engineered for the sole purpose of producing farmed salmon in the open ocean. This massive vessel will be able to house over 2 million salmon and can travel to maintain appropriate water conditions and to avoid storms (NSK Ship Design).

Even if the technology and research exist, one of the biggest impediments to aquaculture development in many areas is public perception of this industry. Of course, public perception varies based on region, especially when looking at this issue from a global perspective. By analyzing over 1,500 newspaper headlines from both developed and developing nations, Froehlich et al. (2017) found significantly more positive headlines about aquaculture in developing nations than developed nations. Overall, they found a growing positive trend in general aquaculture coverage, while offshore aquaculture tended to be more negative. When Froehlich et al. (2017) examined only the headlines that included the term ‘salmon’, the sentiment was overall negative, with Canada contributing 69% of those negative headlines. Therefore, it is likely that salmon aquaculture will struggle even more than other types of aquaculture due to intense criticism in the media. According to Michael Rust, Science Advisor for the Aquaculture Office of the National Oceanic and Atmospheric Administration (USA), aquaculture is struggling to make major advances in places like the United States because of a lack of understanding about what aquaculture entails. He states: “We probably have a farmer in our family tree, maybe a fisherman—as a culture we understand those industries. Very few of us have an aquaculturist in our background”. Rust wants to remind the public that everything we do has an impact on the environment, and he says, “It’s entirely possible to produce farmed seafood in the oceans using existing technologies and have a small environmental footprint”.

With an exploding global population and the food security issues that go hand in hand, aquaculture has the potential to revolutionize the global food market. Currently, only 2% of the global food supply comes from the ocean, even though the ocean comprises 70% of the planet (FAO 2006). A recent study by Gentry et al. (2017) calculated the possible growth of aquaculture on a global scale and found it has the potential to produce 15 billion tons of finfish on a yearly basis. This is over 100 times the current global consumption of seafood (Gentry et 2017). Furthermore, finfish aquaculture production is considered more environmentally friendly in certain ways than farming terrestrial meat sources, like chickens, cows, and pigs. This is due to higher food conversion ratios and less greenhouse gas emissions associated with aquaculture as opposed to livestock production (Hall et al. 2011).

Interdisciplinary collaboration and research will be key to answering the question previously posed: How can we make informed policy decisions regarding the development of the aquaculture industry that will ensure net positive outcomes in the environmental, social, and economic dimensions Aquaculture will surely continue to grow, and with this growth will come new and different challenges. If people are willing to work together—across disciplines, backgrounds, and ideologies—to meet these challenges, I believe we can generate net positive outcomes for the environmental, social, and economic dimensions.

The North Pacific Anadromous Fish Commission (NPAFC) is an international inter-governmental organization established by the Convention for the Conservation of Anadromous Stocks in the North Pacific Ocean. The Convention was signed on February 11, 1992, and took effect on February 16, 1993. The member countries are Canada, Japan, Republic of Korea, Russian Federation, and United States of America.