Course:EOSC270/2022/Group 4 - The Impacts of Salmon Farms on Marine Ecosystems

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What is the problem?

How Do Salmon Farms Work?

Ocean-based open-net pen salmon farm. Multiple cages are connected together in the same region. Each cage contains up to 90,000 salmon.

Salmon farming is usually constructed in a three-stage process: eggs are hatched and salmonoids(young salmon) are raised in the freshwater tank, moved to ocean-based farms for maturing, then placed into water rich in carbon dioxide to be anaesthetized at the time of harvesting.[1] Focusing on the ocean-based farms, a typical cage consists of a metal or plastic frame with mesh netting covering the sides and bottom. [2] The cage may be square or circular, 9 to 27 metres wide and 9 feet deep, where many of these cages are connected in a protected bay and near the shore with each cage holding up to 90,000 salmon.[3] In captivity, salmon are fed pellets containing nutrients, antibiotics and colour enhancers to keep their condition under control.[3]

Human Actions Causing Environmental Problems

Salmon farms are developed and maintained by humans. Therefore, humans are responsible for many aspects of salmon farms that are directly correlated with environmental problems. Below are some of the human actions performed in salmon farms that are causing environmental problems.

Introduction of Invasive Species

The majority of salmon farms use Atlantic Salmon species for farming. According to the WDFW(Washington Department of Fish and Wildlife), Atlantic salmon is favoured to be farmed in cold marine waters because the species grows quickly and consistently, is resistant to disease, and is the preferred appetite for people due to its high-fat content.[4] Atlantic Salmon species are naturally found in the Atlantic Ocean, however, they are raised all across the world by humans to be used for farming. The problem is that in salmon farms, it is expected to have mass escapes of salmon from time to time. When these farmed salmon escape, they can act like invasive species in the wild Pacific Salmon ecosystem because they are notably more aggressive.[5]

High concentration of salmon in a salmon farm. Highly interactive with the surrounding environment.

Chemical Pollution to Local Areas

There are several chemicals used in Canadian salmon aquaculture including pesticides and antibiotics, in order to keep the condition of the salmons under control.[6] The problem is that these foreign compounds may remain in the marine environment, negatively affecting non-target organisms, biodiversity and the ecological structure. [7] Further, open-net farms are enclosed by nylon nets where they are often treated with antifouling paints to avoid fouling. These toxic paints cause impairment of the immune system in bivalves including mussels and oysters, with the potential to be harmful to other fish species as well.[8] Other chemicals, such as pharmaceuticals used to treat sea lice infestations, may also have an impact on the health of non-target wild marine organisms such as crabs, lobsters, and other fish species by disrupting their normal metabolic processes.[7]

How Pervasive are Salmon Farms?

Salmon farming is restricted to areas with suitable ocean temperatures, in which there are only a few countries with coastlines suitable for farming salmon. As of 2018, 98% of the world's supply of farmed salmon were produced by the following five countries: Norway, Chile, Faroe Islands, Canada, and the United Kingdom.[9] Since the population of farmed salmons are intensively concentrated in certain areas, massive in size and highly interactive with the environment, the problem resulting from these salmon farms can spawn serious impacts in the local marine ecosystem.

The Impact of Salmon Farming on Marine Ecosystems

Environmental impacts of salmon farming

Some of the main environmental impacts related to salmon farming that are identified are genetic interactions of escaped salmon with wild salmon, salmon lice, and organic and nutrient load from salmon farms, and overfishing [10].

Salmon Escape

Salmon can escape from the farms due to leakages or storms. Salmon that escape from farms are likely to interbreed with wild salmon or compete for resources with wild salmon and other species within the ecosystem. Genetically wild salmon is different from farmed salmon because wild salmon is adapted to their particular habitat. The effects of interbreeding are quite unpredictable but when related to performance are almost always negative. Secondly, farm salmon are artificially selected for growth and thus have an competitive advantage over wild salmon and other native fish like steelhead in North-America. This leads to a restructuring of the food web in that ecosystem due to the redistribution of nutrients[11].

Pathogens and Parasites

Sea lice as seen on farmed salmon.

Due to the high density of fish in one area for a long amount of time the chances of disease and parasites increases. Salmon lice is one of those parasites that causes major problems. Due to the migratory behavior of salmon from open ocean to freshwater rivers they are at higher risk of getting infected by salmon lice from the farms which are usually located close to the shore and due to the above mentioned problem of escaping salmon whom are often infected. These lice cause swimming and cardiac issues or even mortality in wild salmon[12]. As mentioned above PRV virus is also a very prevalent virus in many salmon farms and is transferred to wild salmon in similar ways as the sea lice[13].

Pollution

Salmon farms are also a major source of pollution to the nearby ecosystems, mainly the organic and nutrients load in these areas is much larger, but also herbicides, antibiotics and other chemicals are released into the ecosystem[10]. Due to this high load of nutrients eutrophication occurs together with events of hypoxia, phytoplankton blooms and lower species diversity and richness[14]. Eutrophication causes a range of problems, starting with a higher microbial oxygen consumption which results in toxic conditions. This causes lower trophic species to decay which has major impacts al throughout the food chain.

Secondly, due to pathogens and parasites like the ones mentioned above a large amount of antibiotics and pesticides are used in salmon farms, and as the sea lice are becoming resistant, farmers are pushed to increase their medicine use resulting in an increased risk of the leakage to the ecosystems.[15] These chemicals leak into the environment and can potentially cause problems like antimicrobial resistance in bacteria, and kill non-target species in the ecosystem. However, the true effect of these chemicals is still largely unknown and needs further research[16].

Overfishing

Overfishing of salmon and other fish populations also has a large impact on the ecosystem. These fish are caught to produce fish feeds like fish meals and oils used in aquaculture, because salmon are carnivorous and require proteins that are now often animal based. Or the fish can be caught to stock the salmon farms. By depleting the populations of these fish the food chain is disrupted and salmon cannot be farmed sustainably[10].

What is the extent of the problem?

Salmon are important to us for a number of reasons, being of an ecological, economical as well as a cultural nature. The consequences of open net-pen salmon farming are widespread and pervasive.

Ecological Risks

Coastlines of the World Affected by Salmon Farms

Across the world sensitive ecosystems are suffering from the impacts of ocean-based salmon farming, next to global warming and habitat destruction. Pacific salmon, of which five subspecies are common in B.C., is on the list of endangered species.[17] But also, the ecosystems as a whole are in danger. One example is the Chilean Patagonia fjord system, which has a very pristine ecosystem, because of its endemic species.[18] The farms in Chile continuously move south towards the more pristine ecosystems when the conditions on their previous farm have become unsuitable.[19]

The sewage waste of a farm will increase when the farm size increases. At its maximum capacity of 1500 tonnes a salmon farm will affect an area of almost 100 football fields of ocean floor, called the footprint of the farm.

By emitting CO2 in the environment resulting from production of feed, transport and energy sources, salmon farms enhance climate change.[20]

Economical and Cultural Risks

The blue revolution has allowed aquaculture to expand more than 20fold from 1970 to 2010.[21] With only a handful of producing countries (see figure 1) and with high demands of the fish worldwide, the salmon market is one of the more valuable markets worldwide. The market is expected to be worth US$ 46.8 Billion by 2026.[22]

Atlantic salmon production of the five main producing countries for the period 1990-2018

Indigenous people (e.g. in Canada and Chile) along with environmental organisations and a growing part of the general public advocate for the phaseout of salmon farms. Salmon in particular serves an important role for the lifestyle and beliefs of indigenous people, because of the salmon's resilient lifecycle, generous food supply, and their role as keystone-species. Salmon is ‘at the top of the totem pole’.[23]

Regulations in the form of fines and policies are being put in place toward less destructive salmon farming. But a lot is to be protected as well, international trade and local jobs.

According to seafood watch the majority of ocean based farms worldwide produce fish which are to be avoided in supermarkets. The only region where the ocean based salmon is produced in a sustainable manner is New Zealand.[24]

Although the salmon production is expected to decrease in the future, the demand is expected to increase rapidly due to rising world populations combined with changing lifestyles in developing countries. If open net-pen salmon farm production grows according to satisfy the demand, all the ecological risks discussed will increase: more escaping fish, more waste and a higher need to find a feed source. This poses an important question for the future: how do we continue farming salmon in a sustainable manner?

Given the impact, what are the solutions?

Solutions in Production

Land-based salmon farm of the company Salmon Evolution under construction in Norway.

On a local scale, solutions include isolation of farmed salmon from wild species, preventing the spread of diseases and reducing waste. These solutions can become global when implemented on a large scale. An illustration of proposed solutions can be given by looking at land-based salmon farming.

Land-Based Salmon Farming

On-land salmon farming is the practice of farming salmon in artificial tanks on land. These could be located anywhere, even in the desert of the UAE.[25] Local salmon production can save up to 50% of carbon emissions by avoiding air transport.[26] As previously discussed, fish sewage is a major consequence of intensive farming. This is not an issue for salmon farming on land, as the waste can be captured from the tank and treated after. Another proposed advantage of on-land farming is that farmed species, that may be genetically modified, cannot escape the tanks. This also limits the spread of diseases and parasites such as sea lice from farmed salmon to wild salmon and vice versa.[27] Development of effective vaccines is a necessity for further sustainable growth of the salmon market.[28] It also helps in the reduction of the use of antibiotics. Lastly, antifouling paints are eliminated by land-based farming.

The proposition of salmon farming on land leans heavily on the use of the principles of the circular economy. Water in the tanks can be recycled and waste can be captured and upcycled to serve as raw materials for biogas or other products.[29]

Problems with Land-Based Salmon Farming

Although companies picture a bright future for on-land farming, there are also concerns, mainly with regards to technological and market feasibility.[27] Salmon farmed on land costs more to produce, resulting in a price premium of 10% - 15% of salmon farmed in the desert of the UAE.[30] Land-based farming will be more costly than its sea-based counterpart in most market scenarios, however, locating farms near to fish-markets may reduce transport costs and emissions significantly.[31] 

Solutions in Consumption

Abovementioned solutions are focussed on reducing environmental impact on the production side. However, this reduction is limited in the near future due to technological and market feasibility.[27] Together with the forecasted increase in salmon demand in developing countries, global solutions include consumer consciousness through creating awareness followed by a decrease in personal salmon consumption through adoption of a vegetarian diet, for example. Research shows that this change in diet decreases GHG emissions, too, although quitting the consumption of fish has a smaller impact than avoiding meat.[32] The diet of the fish is also important, as it on average consists of around 30% fish meal and fish oil. Plant based diets cut out an inefficient food processing step; for 1 kilogram of fish meal or fish oil, 4.3 or 12.5 kilograms of industrial fish has to be caught, which can cause overfishing when not done sustainably.[33] Lab-grown fish may also provide a solution in the more distant future.[34]

References

  1. ↑ "About Salmon Farming". Global Salmon Initiative. March 2017. Retrieved February 22, 2022.
  2. ↑ "Salmon Aquaculture". Georgia Straight Alliance. Retrieved March 4, 2022.
  3. ↑ 3.0 3.1 Hallier, Dave (November 22, 2019). "Salmon Fish Farming". Sciencing. Retrieved February 22, 2022.
  4. ↑ Flatt, Courtney (August 25, 2017). "Q&A: So Why Are Atlantic Salmon In The Northwest?". OPB. Retrieved March 5, 2022.
  5. ↑ Naylor, Rosamond (May 1, 2005). "Fugitive Salmon: Assessing the Risks of Escaped Fish from Net-Pen Aquaculture". BioScience. 55: Pages 427–437 – via American Institute of Biological Sciences.
  6. ↑ Lekang, O. (March 23, 2016). "Challenges and emerging technical solutions in on-growing salmon farming". SpringerLink. Retrieved March 4, 2022.
  7. ↑ 7.0 7.1 Merotto, Leigh (October 28, 2018). "The environmental impacts of open-net salmon farming: A critical review and recommendations for policy in Canadian aquaculture". Ontario Home Economics Association. Retrieved March 3, 2022.
  8. ↑ Guerreiro, Amanda da Silveira (August 2019). "Antifouling biocides: Impairment of bivalve immune system by chlorothalonil". National Library of Medicine. Retrieved March 4, 2022.
  9. ↑ Iversen, Audun (February 2020). "Production cost and competitiveness in major salmon farming countries 2003–2018". Aquaculture: 2 – via Elsevier.
  10. ↑ 10.0 10.1 10.2 Klinger, D. and R. Naylor, Searching for Solutions in Aquaculture: Charting a Sustainable Course. Annual Review of Environment and Resources, 2012. 37(1): p. 247-276.
  11. ↑ Naylor, R., et al., Fugitive Salmon: Assessing the Risks of Escaped Fish from Net-Pen Aquaculture. BioScience, 2005. 55(5): p. 427-437.
  12. ↑ Costello, M.J., How sea lice from salmon farms may cause wild salmonid declines in Europe and North America and be a threat to fishes elsewhere. Proceedings of the Royal Society B: Biological Sciences, 2009. 276(1672): p. 3385-3394.
  13. ↑ Madhun, A.S., et al., Potential disease interaction reinforced: double-virus-infected escaped farmed Atlantic salmon, Salmo salar L., recaptured in a nearby river. Journal of Fish Diseases, 2015. 38(2): p. 209-219.
  14. ↑ David, C.P.C., et al., Coastal pollution due to increasing nutrient flux in aquaculture sites. Environmental Geology, 2009. 58(2): p. 447-454.
  15. ↑ SAMS. (2018, January). REVIEW OF THE ENVIRONMENTAL IMPACTS OF SALMON FARMING IN SCOTLAND. SAMS Research Services Ltd.
  16. ↑ Quiñones, R.A., et al., Environmental issues in Chilean salmon farming: a review. Reviews in Aquaculture, 2019. 11(2): p. 375-402.
  17. ↑ "Facts". World Wild Life.
  18. ↑ Bridson, P. (2014). "Atlantic Salmon, Coho Salmon" (PDF).
  19. ↑ "Chilean Coastal Sea". The Seas Project.
  20. ↑ Liu, Y., Rosten, T. W., Henriksen, K., Hognes, E. S., Summerfelt, S., & Vinci, B. (2016). Comparative economic performance and carbon footprint of two farming models for producing Atlantic salmon (Salmo salar): Land-based closed containment system in freshwater and open net pen in seawater. Aquacultural Engineering, 71, 1–12. https://doi.org/10.1016/j.aquaeng.2016.01.001
  21. ↑ Asche, F., Roll, K. H., Sandvold, H. N., Sørvig, A., & Zhang, D. (2013). SALMON AQUACULTURE: LARGER COMPANIES AND INCREASED PRODUCTION. Aquaculture Economics & Management, 17(3), 322–339. https://doi.org/10.1080/13657305.2013.812156
  22. ↑ Markets, R. A. (2021, June 4). Global Salmon Market & Volume Forecast Report 2021: Market Value is Expected to Reach $46.8 Billion by 2026, Growing at a CAGR of 7.4%. GlobeNewswire News Room. Retrieved February 9, 2022, from https://www.globenewswire.com/en/news-release/2021/06/04/2241901/28124/en/Global-Salmon-Market-Volume-Forecast-Report-2021-Market-Value-is-Expected-to-Reach-46-8-Billion-by-2026-Growing-at-a-CAGR-of-7-4.html
  23. ↑ BC First Nations leaders on the critical importance of wild Pacific salmon | Wild First. (2021, July 29). [Video]. YouTube. https://www.youtube.com/watch?v=w1Tb8OVsRJE
  24. ↑ Search sustainable seafood recommendations by Seafood Watch. (n.d.). Monterey Bay Aquarium Seafood Watch. Retrieved February 9, 2022, from https://www.seafoodwatch.org/recommendations/search?query=%3Afree%3Bsalmon%7Cspecies%3Amethods%3BMarine%20net%20pen
  25. ↑ Moore, G. (2019, March 29). Genuine Scottish salmon, grown in the Middle East. Fishfarmingexpert.Com. Retrieved February 9, 2022, from https://www.fishfarmingexpert.com/article/genuine-scottish-salmon-grown-in-the-middle-east/
  26. ↑ Liu, Y., Rosten, T. W., Henriksen, K., Hognes, E. S., Summerfelt, S., & Vinci, B. (2016). Comparative economic performance and carbon footprint of two farming models for producing Atlantic salmon (Salmo salar): Land-based closed containment system in freshwater and open net pen in seawater. Aquacultural Engineering, 71, 1–12. https://doi.org/10.1016/j.aquaeng.2016.01.001
  27. ↑ 27.0 27.1 27.2 Cox, S. (2020, December 22). Does the future of sustainable salmon lie on dry land? The Narwhal. Retrieved February 9, 2022, from https://thenarwhal.ca/topics/land-based-salmon-farming/
  28. ↑ Lekang, O. I., Salas-Bringas, C., & Bostock, J. C. (2016). Challenges and emerging technical solutions in on-growing salmon farming. Aquaculture International, 24(3), 757–766. https://doi.org/10.1007/s10499-016-9994-z
  29. ↑ Salmon Evolution. (2022, February 2). Sustainability. salmonevolution.no. Retrieved February 9, 2022, from https://salmonevolution.no/sustainability/
  30. ↑ Moore, G. (2019, March 29). Genuine Scottish salmon, grown in the Middle East. Fishfarmingexpert.Com. Retrieved February 9, 2022, from https://www.fishfarmingexpert.com/article/genuine-scottish-salmon-grown-in-the-middle-east/
  31. ↑ Bjørndal, T., & Tusvik, A. (2019). Economic analysis of land based farming of salmon. Aquaculture Economics & Management, 23(4), 449–475. https://doi.org/10.1080/13657305.2019.1654558
  32. ↑ Scarborough, P., Appleby, P. N., Mizdrak, A., Briggs, A. D. M., Travis, R. C., Bradbury, K. E., & Key, T. J. (2014). Dietary greenhouse gas emissions of meat-eaters, fish-eaters, vegetarians and vegans in the UK. Climatic Change, 125(2), 179–192. https://doi.org/10.1007/s10584-014-1169-1
  33. ↑ Norwegian Seafood Council. (2016, May 26). Salmon are fed dry pellets. They contain around 70 percent vegetable ingredients and 30 percent marine raw materials like fishmeal and fish oil. Salmonfacts.Com. Retrieved February 9, 2022, from https://salmonfacts.com/what-eats-salmon/what-does-salmon-feed-contain/
  34. ↑ Fleming, A. (2019, August 1). Could lab-grown fish and meat feed the world – without killing a single animal? The Guardian. Retrieved February 9, 2022, from https://www.theguardian.com/lifeandstyle/2017/sep/20/lab-grown-meat-fish-feed-the-world-frankenmeat-startups
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