Shedding Light on The Situation: Examining the Use of Lighting in Salmon Fisheries

Shedding Light on The Situation: Examining the Use of Lighting in Salmon Fisheries

Light is much like the Force, “Its energy surrounds us, binds us.”, and although most life on our planet requires its presence to survive, light is not a topic the average person spends a great deal of time thinking about (Kershner, 1980). Light impacts all creatures on our planet, defining how they perceive the world around them, shaping how life functions and triggering evolutionary processes. Because of the significance light has on all life, understanding its effects on the life cycles, patterns and development of salmon is essential for salmon fisheries to be able to create environments that produce healthy salmon of the highest quality, reduce the risks associated with early maturation of salmon stocks and improve their overall profits.

Research into the effects of light on fish is nothing new, in fact light has been long used as a tool in fishing, historically being purposed to lure fish to it so they could be captured more easily. Over many years this research discovered that, “(a)tlantic salmon is very sensitive to light, both for smoltification during the freshwater stage and during the on-growing stage in sea water.”. Further studies showed that the use of high intensity artificial lighting in salmon pens can be used “to suppress early maturation during the on-growing stage”, leading many salmon fisheries to implement artificial lighting in their salmon pens (Orrego, 2018.). The impacts of light on salmon development is due to the fact that, much like human beings, fish require a hormone called melatonin to properly sync their biological rhythms, allowing them to determine night from day, the current season and time of day. This process takes place in the pineal gland of fish which works as a mini computer, that absorbs the light signals taken in by the fish and translates them to “rhythmic hormonal signals” that flow through the blood stream providing information that is vital to many species as it often dictates when they rest, mate, hunt, or perform other functions needed for their health and survival (Bruning, 2016). Most melatonin production occurs at night signalling the change in the time of day to the salmon, and triggering a change in their swimming behaviours as their feeding, mating and migration are mainly done during the night where the dark waters can help conceal salmon from predators. This light dependant biological clock that we share with fish is what signals their bodies to develop, grow and reach sexual maturity and allows for the effects of artificial lighting to trick these processes to promote growth while delaying maturity in the salmon. Knowing that the biological process of salmon can be altered using light has promoted further studies into exactly how light impacts salmon stocks, to try and achieve the perfect lighting formula.

Fisheries and Oceans Canada examined two southwestern New Brunswick salmon fishery sites in 2001, and observed that “more than 30% of the fish in some sea cages…” matured earlier than their wild counterparts with speculation that this is due to a lack of light exposure within the pens (cages) (Aquaculture Science Branch, 2012). This early maturation, called ‘grilsing’, results in the quality of the salmon dropping significantly increasing the risk of the grilsing salmon developing health issues, contracting diseases and impacting their market price, if they make it to market at all. These complications result in a domino effect triggered by the removal of stock that is impacted by any disease or health issues, causing additional stress to the healthy salmon in the pen, which negatively impacts their health, perpetuating an infuriating cycle that can be difficult to remedy and can greatly impact the finances of the fishery.

In the 2012 report on the 2001 study from Fisheries and Oceans Canada, analyzed the effects of photomanipulation on salmon in the Bay of Fundy within the two sites in southwestern New Brunswick. This study demonstrated that the time of year in which photomanipulation was implemented could be another major factor in discovering the perfect formula for lighting in salmon fisheries. Site #1 placed two artificial lights in six pens, lighting three on November 21, 2001 and the other three on February 15, 2002 and keeping them lit until May 31, 2002 and allowed for six other pens to be naturally lit as a control. Site #2 had two pens that were lit for 24 hours a day from October 31, 2001 to May 31,2002 and two that were naturally lit as control. Throughout this process the salmon in these pens were constantly filmed and samples were taken from each pen periodically to record their “Sex, round weight, fork length, girth, dressed weight, mean fat content, and gonad weight…” as well as their “length, weight, sex, maturity, and total muscle fat content (leanness)” to compare the lit pens to each other as well as the control pens (Aquaculture Science Branch, 2012).

Their findings showed that while the growth rate of salmon in the artificially lit pens was slower at first, it became “consistently greater than in the control cages”, with the pens that were lit in November producing salmon that were growing “at a rate of 0.32% body mass per day, compared to the control pens at 0.29% per day” [Figure 1]

(Aquaculture Science Branch, 2012). In addition, the rate that the salmon matured was considerably slower in the artificially lit environment than within the naturally lit control pens, with 22% and 17.5% of all the fish in control pens at Site #1 and Site #2 respectively, reaching maturity while the results of maturity in the artificially lit pens produced fascinating results. The pens that were initially lit in February had an average 11% maturity rate in its salmon, while the pens lit in October at Site #2 saw “…8.5% of the males and 1% of the females were mature.” [Figure 2],

but those pens initially lit in “…November showed consistently that only 2% of the males sexually matured and none of the females matured by May 2003.” [Figure 3],

with later experiments showing that lighting pens even as late as December will still yield similar results (Aquaculture Science Branch, 2012). Across all lit and unlit pens the total lipid (fat) levels showed “no detectable difference” in the samples taken in the initial harvest indicating that increasing the salmon’s exposure to constant light does not negatively impact its nutritional value, but does increase its size and delays sexual maturity at a considerable level, especially when this period of increased light exposure runs from late fall/early winter until the end of May. Discovering the optimal time of year and duration of constant light exposure for salmon stocks allows for fisheries to manage the costs associated with operating and maintain artificially lit pens. For each 70m sea pen the estimated “cost of purchasing, wiring, and operating the lights was less than $5,000 per cage (2002 dollars).”, when adjusted for inflation that equates to approximately $7,200 today. While that may not be a small amount of money, “the potential net financial gain from maintaining high production rates and flesh quality, (and) the result of delaying sexual maturity, would be greater than $100,000 per farm.” ($148,000 today) making implementing artificial lighting in salmon pens a worthwhile investment.

Another important piece in the quest to achieve the perfect lighting formula is the type of lighting being used in these processes. While other types of lighting have been used in the past, white metal halide and light emitting diode (LED) lights are now more commonly used in todays fisheries. These two lighting types both share benefits to salmon faming such as an “increased abundance of larval, juvenile and adult fish, and zooplankton in the vicinity of lights, when compared to unlit controls.”, but which is the best?!

White metal halide and LED lights both perform in the same capacity in their ability to draw in other marine life, which drew concerns as to what impact these lights have on the salmon’s diet and other marine animals. Hay et al. (2004) studied whether or not salmon stocks in British Columbia were ingesting wild organisms that had been attracted by artificial light, but found no evidence that proved this was occurring, while “DFO researchers have [recently] examined the stomach contents of harvested farmed salmon and found they were almost all empty. This shows that even when farmed salmon are at their hungriest, right before harvest, they still do not try and eat wild fish.” (Cermaq Canada, 2017). These facts partnered with regulation surrounding incidental catches, greatly lessen the impacts this lighting may have on other marine life.

In a 2012 trial organized by the company Leroy and conducted at Gildeskål  Research Station used the then, “newly designed LED lighting system from Philips” to try and determine what would set these two lighting types apart and determine which was better (Orrego, 2018). Starting the trial in December 2012, LED lighting was placed in two 90 m circumference pens, with two other 90 m pens being fitted with white metal halide lighting. Maintaining a very controlled environment and consistently monitoring the salon and their development, it was found that the LED lights had superior quality when compared to the salmon that had developed in the pens lit by white metal halide lights. Even more impressive was the dramatic difference between the sexual maturity rates between the pens lit by LED lights and those lit by white metal halide lights, with only an average of 0.13% of salmon in the LED pens reaching sexual maturity while an average of 2.58% of those salmon exposed to white metal halide reached their sexual maturity [Table 1].

In regards to the importance of this difference the manager of research and development of the Gildeskål Research Station, Johan Johansen said, “We have used lights during winter and so far assumed that the proportion matured fish is unavoidable background noise, but the solution from Philips close to eliminated all maturation. With good salmon prices the return on investment is very short” (Orrego, 2018). This near elimination of maturity by Philips LED lighting system translates into greatly reduced health risks, an overall higher quality of salmon and larger salmon at time of harvest with the salmon exposed to LED lights producing “3.4% better results for the LED lighting based on harvesting data.” [Table 2] (Orrego, 2018). Impressed with the results of this trial, the Director of Research at the Institute of Aquaculture at the University of Stirling, Professor Herve Migaud stated that “these results clearly showed an increased biological efficiency including suppression of maturation and enhancement of growth as compared to metal halogen…The use of these new systems commercially could contribute to boost productivity while improving fish welfare at sea.” validating LED lighting as the superior lighting choice in salmon fisheries (Orrego, 2018).

The scope of the impact and effect of light on salmon is still being fully examined in hope of creating that ‘perfect’ lighting formula. While the formula for lighting in salmon fisheries has yet to be ‘perfected’, “[t]his is not the end of the journey of improving lighting regimes for the benefit of Salmon farming. Recently the impact of light is further investigated in other applications such as environmental manipulation of salmon swimming depth in order to reduce sea lice infection in Atlantic salmon farms, biomass density control, (and) fish brain development.”, that will all work in tandem to someday achieve that perfect lighting formula for salmon fisheries (Orrego, 2018). But until that formula is discovered implementing the correct type of lighting at the right time of year can greatly improve the quality and health of salmon stocks through drastically reducing their maturity rates and increasing their growth, while reducing the overall production costs and increasing returns for fisheries.

*For more information on the impacts of lighting on salmon fisheries please visit the sources below*

Sources

Aquaculture Science Branch. (2012, May). The Effect of Photoperiod on Growth and Maturation of Atlantic Salmon (Salmo salar) in the Bay of Fundy. Retrieved from Fisheries and Oceans Canada: https://www.dfo-mpo.gc.ca/aquaculture/acrdp-pcrda/fsheet-ftechnique/issue-fiche-14-eng.html

Bruning, A. (2016, October 25). Disruptive light: when night becomes day for fish. Retrieved from IGB: https://www.igb-berlin.de/en/news/disruptive-light-when-night-becomes-day-fish

Cermaq Canada. (2017, December 12). Learning about underwater lights at our salmon farms. Retrieved from CERMAQ Canada: https://www.cermaq.com/wps/wcm/connect/cermaq-ca/news/learning+about+underwater+lights+at+our+salmon+farms

Hay, D. E., Bravender, B. A., Gillis, D. J., & Black, E. A. (2004). An investigation into the consumption of wild food organisms, and the possible effects of lights on predation, by caged Atlantic salmon in British Columbia. Canadian Manuscript Report of Fisheries and Aquatic Sciences 2662: 35 p.

Kershner, I. (Director). (1980). Star Wars: Episode V The Empire Strikes Back [Motion Picture].

Morais, P., Dias, E., Cerveira, I., Carlson, S. M., Johnson, M. C., & Sturrock, A. M. (2018, December 18). How Scientist Reveal The Secret Migrations of Fish. Retrieved from Frontiers for Young Minds: https://kids.frontiersin.org/article/10.3389/frym.2018.00067#:~:text=Like%20birds%2C%20fish%20can%20move,being%20seen%20by%20hungry%20predators.

Orrego, R. (2018, February 24). Effect of LED lighting on growth and development of Atlantic Salmon. Retrieved from Fish Farming Expert: https://www.fishfarmingexpert.com/article/effect-of-led-lighting-on-growth-and-development-of-atlantic-salmon/

Stewart, H. L., Nomura, M., Piercey, G. E., Dunham, A., & Lelliott, T. L. (2013). Ecological Effects of Blue LED Lights Used in Aquaculture. Retrieved from Fisheries and Oceans Canada: https://waves-vagues.dfo-mpo.gc.ca/Library/351062.pdf

The Fish Report. (2018, June 4). Some Like It Dark: Light Pollution And Salmon Survival. Retrieved from FishBio: https://fishbio.com/field-notes/the-fish-report/like-dark-light-pollution-salmon-survival#:~:text=Individuals%20of%20certain%20salmon%20species,a%20lantern%20(USFWS%202015).&text=In%20a%20study%20of%20predation,2012).

 

Fishing for Knowledge: A Brief History of Fisheries in the Canadian North Atlantic

Fishing for Knowledge: A Brief History of Fisheries in the Canadian North Atlantic

The act of fishing has existed long before recorded history and is practiced worldwide making seafood the major source of food for many cultures. Over hundreds of years, as humans evolved and created societies the need for this food source continued to grow and in response commercial fishing began, creating the vital fishing and aquaculture sectors we know today. While fishing is important the world over, this article will focus on the origins of European fisheries in the Canadian North Atlantic that were essential for the development of North America and western society.

1500-1800

The earliest fishermen came to Canada in the 1500’s and began fishing from spring to fall mostly off the Grand Banks of Newfoundland, returning to their respective European countries with their bounty. “The plentiful, easy-to-catch cod was the most valuable commodity: dried or salted, it could be transported long distances and would keep for several months.”, but also fished for other fish species and whales, resulting in the latter’s population being heavily impacted in a relatively short amount of time (Gough & James-abra, 2015). Soon fishing became vital for the growth of these European powers and with what appeared to be endless resources competition between the French and English rose creating two different approaches to the fishing industry.

English fisheries focused on their “semi-permanent fishing stations in protected harbours on Newfoundland’s southeast coast.” With the first captain to reach a harbour governing that harbour (Gough & James-abra, 2015). Most of the fishing was done close to the shore in small boats that would unload their catch onto a “stage” (wharf) to be cleaned and salted, then left to dry on tables that encourages circulation of air called “flakes”, making the easily transportable dried cod that was very popular. Fishermen from New England also came to Nova Scotia in the 18th century to fish the shores and the Bay of Fundy for not only the popular cod but also the Atlantic salmon.  As this fishing industry grew and news of the bounty the new world offered, more and more people came to fish in Canada, resulting in many of the coastal communities that exist today.

Taking a ‘green fishery’ approach to fishing, the French had ports that were scattered along the shores of eastern Canada, as well as on many banks including the Grand Banks. Having more access to salt than the English, and choosing to process the catches directly aboard their ships allowed for the French to be quicker than the English in their fishing methods, although the product did not last as long as the English’s product. This accelerated process allowed for the French ships to return to their fishing stations in Canada more than once in a year. Due to conflicts between the English and French, the French method of fishing was not as widely used as the English approach moving forward.

Schooners, such as the Bluenose built in Lunenburg, Nova scotia, were being built along the shores of the Western Atlantic that allowed for the fishing of halibut, haddock, and mackerel in addition to cod. Schooners also began transporting small boats known as ‘dories’ that allowed fishermen to fish closer to shore where the larger schooner could not reach and using longline fishing techniques developed by the French that allowed for multiple hooks to be in the water at once, attached to an anchored main line, increasing their yields. Another French innovation, the purse seine (net) allowed for an easier catch of herring and mackerel by using nets in the water to catch fish near the surface. “The fishermen tightened a purse line at the bottom of the net to enclose the fish in what looked like a floating bowl.” Allowing for a drastic increase in the amounts of these fish caught (Gough & James-abra, 2015). Also during the 16th century a large seal fishery “which became important in Newfoundland’s growth.” began to develop due to the Conception Bay schooners there and the higher concentration of seal in that area (Gough & James-abra, 2015).

1800-1900

By 1800 the seal industry in Newfoundland was mostly operated by Newfoundlanders rather than seasonal fishermen from Europe and allowed for Newfoundland to amass a fleet of “about 18,000 small boats and 1,200 larger vessels.”, aiding in its economic growth (History of Fishing in Canada 2020).

In 1857 the first Superintendent of Fisheries in what was then Lower Canada, now known as Quebec, created “the first detailed records of planned aquaculture activity in Canada…” (Government of Canada, 2015). This came after they observed and studied brook trout and Atlantic salmon eggs hatching in an incubated and controlled setting, and by 1865 Prince Edward Island began producing oysters. Throughout this century the fleets of Maritime and Newfoundland ships grew quite large and “[a]t Canada’s Confederation in 1867, the federal government was given authority over the fisheries, and set up the Department of Marine and Fisheries.”, which by this time included hundred of lobster canneries, and a crucial sardine-canning industry (Gough & James-abra, 2015).  This appointment gave rise to regulations that “aimed mostly to protect salmon and inshore fisheries, where problems were most visible “, with other “set rules on gear types, size limits, and seasons for dozens of fisheries…” coming near the end of the century and early into the 19th century. Also “[n]ear the end of the century, an effort to increase the depleted cod population off the coast of Newfoundland began with a cod hatchery established in 1889 on Dildo Island and “released over a billion cod fry into the waters of coastal Newfoundland”, (Government of Canada, 2015). It was during this post-confederation era that the fisheries industry began to seek to conserve fishing and seek more sustainable practices, developing rules and restrictions “of fishing times and seasons, fish size, and fishing gear” while “The Fisheries Act also outlawed putting substances that would be harmful to fish into the water.” (Gough & James-abra, 2015). “In 1898 the federal government established the first of several biological and technical research stations under the Biological Board of Canada (later the Fisheries Research Board).” to monitor fishing practices and seek to innovate the industry to be more sustainable. These rules and restrictions were the base of the laws we have today, with many of the original rules and restriction still being enforced.

1900-1959

 With Confederation giving rise to more regulations and rules regarding fishing and fisheries in the North Atlantic waters, the final decisions on what was acceptable was left to each province. This allowed the North Pacific (British Columbia) to also experience a growing economy thanks to the income from their fishing industries, with the Pacific salmon industry becoming the leading fish to be traded at beginning of the 20th century, dwarfing even the highly important halibut and herring trades. Although salted groundfish was still the main trading seafood, scallops and swordfish began to have their own fisheries developed at the beginning of the 19th century.

The World Wars and The Great Depression hit the Maritime and North Atlantic fishing industries hard prompting the Royal Commission of 1927 resulting in “the trawler fleet [being] reduced to only three or four vessels during the 1930s.” (Gough & James-abra, 2015). “Although the Lunenburg fleet in particular was doing more winter fishing  for the fresh-fish market, the trawler “ban” slowed the growth of the fresh, fresh-frozen, and year-round fisheries.” further damaging the economic status of the fishing industry in the Canadian North Atlantic. This combined with the failing economy, a decreased demand, and other financial issues created a perfect storm that delayed the technological advancement of the industry for several decades.

After the wars many innovations to the fishing industry occurred such as; the American development of the “filleting and quick-freezing processes, enabling them to sell packaged fresh or frozen fillets, instead of whole fish, to a wider market.”, and the use of military technology like radars, sonar, radios, nylon nets and hydraulic gear. Governments began to once again encourage these advancements and began to put supports in place to help struggling fishermen and encourage the industry to grow again. These measures also saw the government encourage the fishing of redfish, flounder, flatfish, crab, shrimp, and offshore scallops, and to allow trawler fleets to grow, with some companies having 150 trawlers in their fleets. This push for growth in the industry did have negative consequences in the North Atlantic in the forms of overfishing and overcapacity, “the term used when fishermen’s ability to catch fish, using whatever technology was available to them, meant too many fish were being caught from a conservation perspective.” (Gough & James-abra, 2015).

1960-2000

During the 1960’s and 1970’s pressure began to be put on the fishing industries to be better managed. While fishing on the Pacific coast was banned from 1967-1972 due to the overfishing of herring, fishing on the Atlantic coast was encouraged and still thriving, at dangerous levels that depleted stocks at accelerated rates and damaged ocean ecosystems and wildlife populations. Fishing licences were soon required by all fisheries and fishermen, however “fishermen could in effect buy and sell them and there was no direct control on the number of fishermen fishing.” (Gough & James-abra, 2015). Many other regulatory changes occurred over this time, however the economic, environmental, and social issues that arose from the fishing industry continued to grow. British Columbia was one of the first provinces to develop superb fishery and aquaculture management even with a smaller fleet of ships, due to the increased levels of education, oversight and regulations that controlled their fishery industry due to their “strong local organizations” while the Atlantic fishing industry did not provide as much support for their local and independent fishermen.

Throughout the 1970’s many provinces followed B.C.’s lead and strived to better manage their own fishery operations. This era saw both prosperous times and times of struggle, with the end of the 70’s seeing licensing becoming required for all fishing and the government establishing the Department of Fisheries and Oceans as its own department in 1979. The Fisheries Council of Canada also played a part in representing fish processors “whose plants came under provincial control but many processors-controlled vessels, and the FCC exerted strong influence on the federal fisheries department.” (History of Fishing in Canada 2020). These newly established institutions helped to develop salmon and trout aquaculture, helped promote wide-scale commercial activity, and oversaw the management of many fishing institutions.

In the 1980’s commercial scale marine finfish aquaculture began in Canada, and BC began to import and farm Atlantic salmon, helping the province to take the lead in the fishing industry. By 1988 the value of aquaculture production in Canada is calculated to be an “impressive $433 million” (Government of Canada, 2015). In 1989 a major problem was discovered when inshore fishermen in Newfoundland discovered that the once abundant cod fish were becoming fewer and fewer in their numbers, prompting the government to examine why this was occurring (spoiler, it was from over fishing).

The 1990’s saw a move in the industry from small independent fisheries to larger consolidated companies, while a high number of escaped salmon is discovered in BC fisheries prompting another change in the way fisheries are managed, aiming to “achieve “zero escape” of fish from net-pen facilities.” (Government of Canada, 2015). During this decade, the aquaculture industry value rose to $558 million. In 1992 after years of research and studies, the Fisheries and Oceans Minister John Crosbie instituted a moratorium on cod fishing in the North Atlantic, to allow the decimated population to ‘bounce back’. Once believed to be able to feed the world until the end of time, cod hauls had dropped by over 600,000 tonnes between 1988 and 1995, resulting in the leader of the Newfoundland Fishermen and Allied Workers Union leader Richard Cashin to call the situation “a famine of biblical proportions.” (Marsh & Tattrie, 2016). This discovery also helped to push for the creation of the Fisheries Resource and Conservation Council that was made up of academics, scientists and government officials, and those within the industry to help make the regulations, rules and laws surrounding fisheries and aquaculture in Canada. By 2000 the entirety of Canada’s seafood industry was valued at $1.77 billion.

2001-Present

After the push for sustainable and accountable fishery and aquaculture management and practices in the 1980’s and 1990’s, the 2000’s continued to build upon theses beliefs and further researched better ways to create a healthier, environmentally conscious and sustainable aquaculture and fishing industry, that now existed across Canada. There are now “45 species of finfish, shellfish and marine plants…raised commercially in Canada.”, with the majority being salmon from British Columbia and New Brunswick Oysters and mussels from Prince Edward Island and trout from Central and Western Canada. Shellfish had also overtaken groundfish during the late 90’s as the dominant industry in the aquaculture and fisheries sector and continues to rise. These changes, regulations, practices, and policies also helped to create a safer environment for fishermen as well as increased compensation. In 2010 the seafood industry in Canada was valued at $1.3 billion dollars, demonstrating how vital the industry continues to be for our society and economy.

Fishing is in all our histories and the aquaculture and fishery industry in the Canadian North Atlantic has helped shape the industry across the globe and helped make our country what it is today. The fishing and aquaculture industries provide work to thousands of people across the globe and, as a result, provides food for millions. Noting that most innovations in the industry and its management have only occurred over the last 50 years, the future of the seafood industry is bright and always changing. Be sure to keep an eye out for our follow up blog about the future of the fishery and aquaculture industries.

*For more information on the history of fisheries and aquaculture in Canada please visit the sources below*

SOURCES:

  1. (2020). History of Fishing in Canada. Retrieved October 05, 2020, from http://www.fishharvesterspecheurs.ca/fishing-industry/history.

Cook, R. (2019, February 14). Atlantic Cod: The good, the bad, and the rebuilding – Part 1. Retrieved October 04, 2020, from https://sustainablefisheries-uw.org/fishery-feature/atlantic-cod-part1/.

Finley, C. (2013, November 27). The role of fish in the World War II war effort. Retrieved October 04, 2020, from https://carmelfinley.wordpress.com/2013/11/18/the-role-of-fish-in-the-world-war-ii-war-effort/.

Gough, J., & James-abra, E. (2015, July 23). History of Commercial Fisheries. Retrieved October 05, 2020, from https://www.thecanadianencyclopedia.ca/en/article/history-of-commercial-fisheries.

Government of Canada, F. (2015, March 03). Farming the seas – A timeline. Retrieved October 04, 2020, from https://www.dfo-mpo.gc.ca/aquaculture/sector-secteur/frm-tml-eng.htm.

Holmyard, N. (2019, July 17). New study maps out how the world’s fisheries are interconnected. Retrieved October 06, 2020, from https://www.seafoodsource.com/news/supply-trade/new-study-maps-out-how-the-world-s-fisheries-are-interconnected.

Marsh, J. H., & Tattrie, J. (2016, March 1). Bluenose. Retrieved October 06, 2020, from https://www.thecanadianencyclopedia.ca/en/article/bluenose.

National Museum of Natural History, S. (2019). On the Water. Retrieved October 05, 2020, from https://americanhistory.si.edu/onthewater/exhibition/3_4.html.

Perspective. (2018, August 09). Canada’s Aquaculture contributes $3.1 billion to Economy. Retrieved October 05, 2020, from https://perspective.ca/canadas-aquaculture-contributes-3-1-billion-to-economy/.

Stokstad, E. (2019, May 27). Fishing fleets have doubled since 1950-but they’re having a harder time catching fish. Retrieved October 05, 2020, from https://www.sciencemag.org/news/2019/05/fishing-fleets-have-doubled-1950-theyre-having-harder-time-catching-fish.