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Salmon aquaculture pens

Salmon aquaculture pens (shaunl, iStockphoto)

STEM in Context

Farmed Salmon vs. Wild Salmon

Jacob Fine

Summary

Aquaculture is seen as a sustainable way to produce fish. But are farmed salmon better than wild fish?

Do you eat salmon? If so, how do you like it? Do you barbeque it? Do you have it as sushi? Do you steam it with veggies?

If you’ve ever bought salmon from the grocery store, you might have noticed all kinds of information on the packaging. You might have seen the type of fish as Pacific or Atlantic salmon. Or you might notice it is labelled “farmed” or ''wild.” What does it even mean to farm fish? It is important to ask this question, because the way that food is produced can affect the environment and your health.

 

Did you know?

Farming fish and other species that live in water is known as aquaculture.

There are five types of wild salmon found on the Pacific coast (sockeye, pink, chum, chinook, and coho) and one type found on the Atlantic Coast (Atlantic)
There are five types of wild salmon found on the Pacific coast (sockeye, pink, chum, chinook, and coho) and one type found on the Atlantic Coast (Atlantic) (Sources: U.S. National Marine Fisheries Service via Wikimedia Commons and Knepp, Timothy via Wikimedia Commons).

Let’s learn about what a fish farm is. Then, we’ll discover some of the problems and benefits fish farming can bring. Finally, we’ll look at how to farm fish sustainably. 

What does “farming” fish mean?

Net pens at a salmon farm near Briar Island, Nova Scotia
Net pens at a salmon farm near Briar Island, Nova Scotia (Source: Andyqwe via iStockphoto).

Essentially, a fish farm, also known as an aquaculture, is a large enclosure that humans control. In Canada, salmon farming typically takes place in either net pens in the ocean or tanks on land. 

Net pens are cage-like structures. They are made out of nets in open bodies of water. There are different types of net pens based on their distance from the shore. Coastal or inshore aquacultures are located near the shore. Ocean or offshore aquacultures are located far from the coast. 

Raising fish on land in tanks is known as land-based aquaculture. This is a lot like raising fish in giant swimming pools. 

What are some of the problems with farmed salmon?

Farming salmon can help maintain populations of salmon that are used for food. But some people have concerns with farming practices.

Net pens can house thousands of salmon in a fairly small area. This means these salmon live in cramped quarters. Often, salmon grown in net pens can have health issues. This makes them easy targets for sea lice, which can be dangerous to the young fish. Also, fish farms produce waste such as fish excrement, uneaten food, and chemicals. This waste can concentrate under pens in shallow water. This can impact the environment, including nearby wildlife. 

Did you know?

Fish in farms are more likely to have warped skeletons than wild fish. But scientists aren’t sure why.

There can also be problems if salmon escape from the net pens. Escaped fish compete for food and can spread parasites and other diseases to healthy wild fish. 

Another problem is that escaped farm fish could breed with wild salmon. Since farmed salmon are not as capable of surviving in the wild, their offspring might not be either.

Infographic of some of the problems associated with net-raised fish
Infographic of some of the problems associated with net-raised fish (© 2019 Let’s Talk Science).

Health professionals often recommend eating salmon instead of red meat. They say salmon is healthier. But some people have concerns about eating farmed salmon. Farmed salmon cannot catch their own food. Instead, they are fed high-fat, high-protein diets. This can make them less nutritious than wild salmon. 

Farmed salmon can also have larger amounts of organic compounds, called polychlorinated biphenyls (PCBs), than wild salmon. Studies show that PCBs can cause a number of different cancers and other toxic effects in humans.

Did you know?

By 2030, two thirds of the world’s fish is expected to come from aquaculture. 

Salmon Farming in Canada 

The Government of Canada reports an average of 122 300 tonnes of salmon was produced from 2011 to 2015, with British Columbia producing 60% of this. Other contributors include Newfoundland and Labrador and New Brunswick, which mainly raise Atlantic Salmon.

2014 Canadian aquaculture production of fish and shellfish
2014 Canadian aquaculture production of fish and shellfish (Source: Fisheries and Oceans Canada).

How can we farm fish sustainably?

As you can see, farmed fish can have some serious impacts on human health and the environment. But the aquaculture industry is not going away. There are almost 60 million people working in the aquaculture industry around the world. That number will continue to grow. According to the United Nations, fish are an important source of protein, vitamins, and minerals. Farmed fish have the potential to feed billions of people. After all, the world’s population is growing. Fishing in the wild can’t keep up with the demand of feeding all these people! Eventually, farming fish might be our only option. That’s why it’s important to do it sustainably.

Did you know?

Some people argue that farming fish is better for the planet than farming cattle, poultry, or pigs

A recirculating aquaculture system
A recirculating aquaculture system (Source: Narek75 [CC BY-SA 4.0] via Wikimedia Commons).

How can we keep farming fish, but minimize harm to us and to the ecosystem? In other words, how can we practice sustainable aquaculture? Scientists and fish farming companies around the world are working tirelessly to find an answer. 

One solution is doing more land-based aquaculture. This form of fish farming is far less threatening to sea life than net pens. But it can be more expensive to run. For example, a recirculating aquaculture system is essentially a large, complicated aquarium. They come with some costs that net pens don’t. For example, they need heating, electricity, and more human staff. 

Another possible solution is growing fish in giant offshore aquapods. An aquapod is essentially a large, spherical cage suspended in the ocean. The water in these pods tends to be cleaner than in net pens. One reason is because they are suspended further from coastlines. There, waste will drift away with the current instead of building up.

If governments and fish farming companies continue to invest the time and resources, sustainable aquaculture might be a realistic possibility. Taking better care of the fish today will enable us to take better care of ourselves tomorrow.

Starting Points

Connecting and Relating
  • Does your family like to eat salmon? Do you know how the salmon you eat was produced? 
  • Do you think the benefit of adding more fish protein to your diet outweighs the potential risks associated with eating farmed fish? Explain.
  •  
Connecting and Relating
  • Does your family like to eat salmon? Do you know how the salmon you eat was produced? 
  • Do you think the benefit of adding more fish protein to your diet outweighs the potential risks associated with eating farmed fish? Explain.
  •  
Relating Science and Technology to Society and the Environment
  • How could fish farming help with global food sustainability?
  • Why is there room for growth in fish farming in Canada? 
  • How might economics influence the type of fish farming that is practiced in an area? What other factors can influence fish farming practices?
  •  
Relating Science and Technology to Society and the Environment
  • How could fish farming help with global food sustainability?
  • Why is there room for growth in fish farming in Canada? 
  • How might economics influence the type of fish farming that is practiced in an area? What other factors can influence fish farming practices?
  •  
Exploring Concepts
  • What are the two common types of fish farming? 
  • Identify at least three concerns about fish farming
  • Why is there concern about PCBs in farmed fish? 
  • What solutions are possible for improving the water conditions for farming fish?
  •  
Exploring Concepts
  • What are the two common types of fish farming? 
  • Identify at least three concerns about fish farming
  • Why is there concern about PCBs in farmed fish? 
  • What solutions are possible for improving the water conditions for farming fish?
  •  
Nature of Science/Nature of Technology
  • Is farming fish a totally new practice? What aspects of modern fish farming rely on modern techniques and technologies?
Nature of Science/Nature of Technology
  • Is farming fish a totally new practice? What aspects of modern fish farming rely on modern techniques and technologies?
Media Literacy
  • Have you seen any news reports or documentaries about fish farming? Did the report or documentary appear biased? That is, did the documentary focus solely on either the negative impacts of fish farming or the benefits of fish farming? Was the report or documentary unbiased? Why or why not?
Media Literacy
  • Have you seen any news reports or documentaries about fish farming? Did the report or documentary appear biased? That is, did the documentary focus solely on either the negative impacts of fish farming or the benefits of fish farming? Was the report or documentary unbiased? Why or why not?
Teaching Suggestions
  • This article can be used to support teaching and learning in Biology, Health and Environmental Science related to aquaculture, fisheries and sustainability. Concepts introduced include fish farm, coastal or inshore aquacultures, ocean or offshore aquacultures, polychlorinated biphenyls (PCBs), sustainable, land-based aquaculture, recirculating aquaculture system and aquapods.
  • After reading this article, to help students consolidate learning, teachers could have students consider the positive and negative aspects of fish farming using a Pros & Cons Organizer learning strategy. Ready-to-use Pros & Cons reproducibles are available in [Google doc] and [PDF] formats. 
  • To go further, teachers could have students look at the impacts of starting a new net pen fish farming operation in a coastal community in Canada from the perspective of a variety of stakeholders, using an Issues & Stakeholders learning strategy. Ready-to-use Issues & Stakeholders reproducibles are available in [Google doc] and [PDF] formats.
  •  
Teaching Suggestions
  • This article can be used to support teaching and learning in Biology, Health and Environmental Science related to aquaculture, fisheries and sustainability. Concepts introduced include fish farm, coastal or inshore aquacultures, ocean or offshore aquacultures, polychlorinated biphenyls (PCBs), sustainable, land-based aquaculture, recirculating aquaculture system and aquapods.
  • After reading this article, to help students consolidate learning, teachers could have students consider the positive and negative aspects of fish farming using a Pros & Cons Organizer learning strategy. Ready-to-use Pros & Cons reproducibles are available in [Google doc] and [PDF] formats. 
  • To go further, teachers could have students look at the impacts of starting a new net pen fish farming operation in a coastal community in Canada from the perspective of a variety of stakeholders, using an Issues & Stakeholders learning strategy. Ready-to-use Issues & Stakeholders reproducibles are available in [Google doc] and [PDF] formats.
  •  

Learn more

The State of the World Fisheries and Aquaculture (2018)

Information sheet, from Food and Agriculture Organization of the United Nations, about global aquaculture; contains a lot of information, as well as data displayed as statistics and graphs.

Wild vs. Farmed Salmon: Which Type of Salmon Is Healthier? (2019)

Article by Healthline which compares the nutritional differences between farmed and wild salmon.

Aquaculture can feed the world, new report claims (2017)

Article by Nicki Holmyard which discusses a University of California report that suggests that aquaculture may be the solution to global food shortages. 

Salmon and Trout of Lake Ontario: A Visual Identification Guide

A visual guide to identifying Lake Ontario salmon and trout species produced by Sea Grant, New York.

How Seafood is Farmed: Net Pens (2013)

Using animations (1:30 min.), Seafood Watch briefly introduces the subject and mentions some ways to reduce potential harms.

References

Food and Agriculture Organization of the United Nations. (2019). 2018 the state of the world fisheries and aquaculture.

Government of Canada. (2017, March 15). Farmed salmon.

Government of Canada. (2019, January 25). Managing organic wastes.

Green, D. M., Penman, D. J., Migaud, H., Bron, J. E., Taggart, J. B., & McAndrew, B. J. (2012). The impact of escaped farmed Atlantic salmon (Salmo salar L.) on catch statistics in Scotland. PLoS One, 7(9). DOI: 10.1371/journal.pone.0043560

Konstantinovsky, M. (2019, January 11). Is farmed salmon bad for you? One Medical.

Searchinger, T., Waite, R., Hanson, C., Ranganathan, J., Dumas, P., & Matthews, E. (2018, December). Creating a sustainable food future. World Resources Institute.

Smart, A. (2017, December 3). Are land-based fish farms a financially viable option? Times Colonist.