Arctic char in a rapidly changing North

Executive Summary

Fish have been central to Inuit culture, food security, and health for millennia. Arctic char are a staple across Inuit Nunangat. Small commercial char fisheries provide jobs in some communities.

Research has shown that sea ice conditions, temperature, salinity, prey, and possibly predators, can all influence where Arctic char go in the ocean as well as their health. Temperature is among the most important of these conditions. Char may react to warming ocean waters. With a shorter sea ice season, sea-run char may migrate to the ocean earlier and spend longer feeding there. They may stay longer in deeper waters, in the cooler temperatures they prefer. They may spend more time away from the shore as shallow waters near land become warmer.

In warmer waters, char need to eat more. In cooler water, Arctic char need less food. This may be why they move further from shore or into deeper, cooler water later in summer.

Changes in their diet can mean the food available to them is changing. Recent warming and sea ice retreat have brought southern fish species, such as capelin and salmon, to Arctic waters. Community experts are monitoring these new arrivals — some have observed that flesh of char that eat capelin tends to be paler — but it is still unclear how they are affecting Arctic char and other Arctic species. Salmon moving north may affect char living in more southern parts of the Arctic. However, the southern range of Atlantic salmon overlaps with that of char, and the two species do not compete for spawning areas as they spawn in different kinds of habitat. More research is needed to learn how southern fishes moving north affect char.

Earlier ice breakup has improved the condition of Arctic char in some areas, possibly because they have a longer time to feed in the ocean.

The amounts of persistent organic pollutants, such as PCBs, are declining in Arctic char. Mercury, which occurs naturally, can increase in the environment because of dams and mining. This is a concern in Nunatsiavut. Research shows that the levels of mercury in sea-run Arctic char are very low, well below the amounts allowed by commercial sale guidelines. Char that never migrate to the ocean, especially those living in smaller lakes, are more likely to have higher levels.

We need to understand more about the factors that influence the abundance, accessibility, quality, and stability of Arctic char stocks, now and in the future. Through strong and equitable partnerships between researchers, communities, and Indigenous Knowledge holders, we will gain that understanding.

Authors and contributors

• Les N. Harris* Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, MB, R3T 2N6 Les.N.Harris@dfo-mpo.gc.ca
• Jean-Sébastien Moore* Université Laval, 1030 Avenue de la Médecine, Québec, QC, G1V 0A6 jean-sebastien.moore@bio.ulaval.ca
• Karen Dunmall Fisheries and Oceans Canada
• Marlene Evans Environment and Climate Change Canada
• Marianne Falardeau Université Laval
• Colin P. Gallagher Fisheries and Oceans Canada
• Matthew Gilbert University of New Brunswick
• Tiff-Annie Kenny Université Laval
• Darcy McNicholl Fisheries and Oceans Canada
• Norman Mike** Pangnirtung, Nunavut
• George Lyall** Nain, Nunatsiavut
• Laurent Kringayark** Naujaat, Nunavut

* Co-first-authors/Corresponding authors

**Indigenous Knowledge Holders

Citation information

Harris, L., Moore, J.-S., Dunmall, K., Evans, M., Falardeau, M., Gallagher, C., Gilbert, M., Kenny, T., McNicholl, D., Norman, M., Lyall, G. and Kringayark, L. 2022. Arctic char in a rapidly changing North, Polar Knowledge: Aqhaliat Report, Volume 4, Polar Knowledge Canada, p. 34–57. DOI: 10.35298/pkc.2021.02.eng

Introduction

Fish have been central to Inuit culture, food security, and health for millennia. Abundant, nutritious, and prized for their flavour, fish – especially Arctic char – are a staple in communities across Inuit Nunangat.

Inuit catch and consume different types of fish including Dolly Varden, Lake Trout, and Whitefish. However, in Nunavut, Arctic char is harvested the most in every community.¹ It is a very important local food source, with high cultural value. Replacing Arctic char with market food would cost about $7.2 million a year.² Additionally, Arctic char has a commercial fishery that employs dozens of Nunavummiut and has a quota of about 677,220 kgs. There are 200 other commercial quotas available, but many are not being used. Some communities would like to expand the fishery to provide more jobs.

Arctic char is the world's most northerly freshwater fish. Char living in lakes without access to the ocean are called "landlocked Arctic char." Some, known as sea-run Arctic char, inhabit lakes with ocean access and migrate to the ocean in summer. Others, called "freshwater residents," live in lakes connected to the ocean, but never migrate. In Inuit communities, the sea-run fish are most important for both the subsistence and commercial harvests. In the Arctic, marine waters are more productive (meaning there is more food to eat) than freshwater, so that sea-run fish grow larger.³ Climate change may increase the amount of food for char in freshwater, and some studies suggest that the number of freshwater residents could increase, while sea-run fish become fewer.⁴ This could affect fisheries, as sea-run fish are larger and more valuable.

This paper provides information on some of the recent research on Arctic char, focusing mostly on sea-run char. It addresses thematic questions developed at the Regional Planning and Knowledge Sharing Workshop (see Introduction of the Collaborative Assessment). A table at the end shows how ecological information relates to food security.

Arctic char habitat use and how it could change in the future

Northern sea-run Arctic char hatch in freshwater and stay in lakes and streams for 4 to 7 years.^{5, 6} Then they migrate to the ocean to feed.^{5, 7} Before winter, when the seawater becomes too cold for them to survive, they return to freshwater.^{5, 7, 8}

Arctic char migrate like this throughout their lives, and they can live more than 30 years. They spawn many times, unlike their relatives, Pacific salmon, which die after spawning. Arctic char do not tolerate highly salty water well, so they cannot live long in full-strength seawater.

Movement and habitat use in the ocean

Arctic char typically migrate to the ocean when the river ice breaks up in spring, while sea ice is still present. They return to rivers towards the end of August.^{9, 10} We have improved our understanding of where Arctic char go by tracking a small number of them with tags, implanted under their skin, which send an acoustic signal.⁹ Other studies have tagged hundreds or thousands of fish with plastic ID tags, which have provided valuable information on migration patterns. A few char have been recaptured hundreds of kilometres away from where they were tagged.¹¹

This research has shown that sea ice conditions, temperature, salinity, prey, and possibly predators, can all influence where Arctic char go in the ocean.^{12, 13} It has also clearly demonstrated these patterns:

• While in the ocean, Arctic char spend most of their time in estuaries (where rivers enter the ocean), often preferring these habitats until the sea ice disappears.^{12, 13} In some areas this coincides with the spring tides.
• Char stay close to shore (usually within 1 km) and remain in one estuary for a few days before moving quickly to the next estuary. Scientists are not certain why they prefer estuaries: they may prefer the warmer and less salty water near rivers. There may also be more food in estuaries.
• Arctic char usually stay within 1 to 3 metres of the surface.¹⁴ The top layer of the ocean is warmest and least salty, and most of their prey live there. The fish occasionally dive down below 30 metres, probably to feed on prey in the deeper waters. There the water is colder and saltier, and so the fish soon return to the surface. Later in summer, Arctic char move deeper in the ocean¹³ and possibly further from shore.
• Arctic char spend the day further down and come up at night, probably to feed on prey that do the same.^{12, 13}

From this information we can predict how Arctic char may react to warming Arctic Ocean waters:

• If rivers break up earlier and freeze up later, the fish may migrate to the ocean earlier and return later, allowing them to spend a longer time feeding there.
• If surface waters warm, they may stay longer in deeper waters in the cooler temperatures they prefer.
• They may spend more time away from the shore as shallow waters near land become warmer.

More long-term studies will improve understanding of how year-to-year changes in the environment influence the way char behave in the ocean as marine waters continue to warm.

The effects of temperature on Arctic char

Temperature affects where Arctic char go and how they use their habitats. Temperature also influences their health and metabolism (how their bodies use energy).

Arctic char are a cold-water fish – they can grow at temperatures as low as 0°C – but like all living things they do best in a certain temperature range. In the warmer part of that range their bodies perform better. They grow more quickly, their heart beats more rapidly, and they can swim faster.

When the water warms to about 16°C though, the reverse happens, and their performance decreases.15 Above 16°C it is harder for them to recover from exercise (like migration). Above 18°C, they can no longer eat, and by 21°C their heart begins failing. At 23°C they cannot stay upright.^{15, 16} Arctic rivers are sometimes warmer than 21°C, and this limits where and when Arctic char can successfully migrate.

Oceans in the central Canadian Arctic stay well below these temperatures, usually remaining below 12°C. Recent research has shown that warmer summer ocean temperatures and longer ice-free periods are not harming adult Arctic char.¹⁷ Some data suggests that they grow more when the ice-free period is longer.¹⁸

In warmer waters, the metabolism of Arctic char increases, and they use more energy – which means they need to eat more. Food is often limited though, and by moving to cooler water where they need less energy they can probably grow more quickly. Laboratory studies have shown that in cooler water Arctic char need less food to grow.¹⁹ This may be why the sea-run Arctic char move further from shore or into deeper, cooler water later in summer.

The diet of Arctic char

In winter, when they are in ice-covered lakes, sea-run Arctic char eat very little. They get most of their food in the summer when they are in the ocean.²⁰ During their short ocean feeding season, they must eat enough to migrate back to freshwater, possibly spawn, survive the winter, and migrate back to the ocean the following year.⁵

Arctic char feed on many kinds of marine prey. They eat small and large fishes, zooplankton (small aquatic animals), larger crustaceans (amphipods and decapods, and shrimp-like creature such as mysid), and small insects.^{12, 21, 22}

Research suggests that Arctic char eat mostly amphipods and mysid shrimps. They also eat copepods, which are small crustaceans. These tiny animals live near shore under sea ice. As the ice disappears, they move deeper and further from shore, and the char follow them.

Fish also make up a large part of the Arctic char diet. They eat Arctic Cod, Sculpins, and occasionally other Arctic char. Recently, they have been eating Capelin and Sand Lance.²³ In the future, they may eat less Arctic Cod, because that species needs to live under sea ice for part of its life cycle. Arctic Cod may become less plentiful in lower Arctic latitudes as a warming climate reduces the amount of sea ice with continued climate change.²⁴

Arctic char is a healthy food because of the nutrients, vitamins, and good fats its flesh contains.²⁵ These come from what the fish eats. The healthy omega-3 fats in Arctic char flesh,²⁶ come from small Arctic crustaceans. The pigments that give char flesh its reddish colour are beneficial to human health.^{27, 28} They come from animals such as copepods that feed on microscopic algae.

Recent warming and sea ice retreat have brought southern fish species such as Capelin, Sand Lance, and Salmon to Arctic waters.^{29, 30, 31} Also, earlier sea ice breakup has changed the time of peak production, when marine plants and animals are most plentiful. Both of these factors have affected Arctic marine food webs and char diet. Arctic char can act as a "sentinel species," meaning that what they are eating shows what prey are available in the environment. Changes in their diet can indicate changes in the marine food web. For example, in the Qikiqtaaluk (Baffin) region, char have recently shifted to eating Capelin – which shows that Capelin are getting more abundant there.^{22, 32} In the Kitikmeot region, char are feeding on prey near the surface more than before.³³

Some indicators of fish quality, such as condition (how heavy it is for its length) and the amount of nutrients they contain, have changed in the past few decades. This may reflect how char are responding to climatic and food web changes. For instance, earlier ice breakup and longer ice-free seasons have improved the condition of Arctic char in some areas.^{18, 33, 34} This may be because they have a longer time to feed in the ocean. Some researchers think that changes in the types of marine prey, caused by climate change, may be influencing the colour of Arctic char and their nutrient and fat content. There is not yet enough evidence to confirm that this is true; but it will be important to understand how changes in Arctic char prey may influence food security and health in northern communities.

Contaminants in Arctic char

Northerners are concerned about pollutants in country foods, including Arctic char. In the early 1990s, the federal government's Northern Contaminants Program (NCP) began to investigate Persistent Organic Pollutants (POPs) in Arctic animals. These include PCBs, used in inks, transformers, etc., and DDT, used to kill insects. Many of these chemicals travelled up from the south on ocean and air currents. Others were used in the north – at former Distant Early Warning (DEW) Line sites, for example.

In the 1950s, after researchers found these chemicals in remote environments and proved they could cause harm (e.g., DDT caused some bird eggshells to become too thin), governments developed regulations to control their use. Bans and restrictions followed in the 1970s. In 2001, 152 countries signed the Stockholm Convention on Persistent Organic Pollutants, an international treaty to eliminate or restrict the production of pollutants such as PCBs. This was effective. Industries now use these chemicals much less and they are declining in the environment. Programs such as NCP are monitoring the decline in POPs in Arctic and subarctic animals.

The number of pollutants in traditional foods depends on many factors. Some chemicals build up in an animal over time, so that an older animal can have more in its body than a younger one. An animal's size is also a factor. A small fish like a Sculpin will have less for its size than a large Lake Trout. This is because the pollutants from all the small fish the large fish eats build up in its body. Fish have less pollutants in their bodies than warm-blooded animals. This is because they eat less than warm-blooded animals of the same size, as they do not need as much food to keep warm. Because they eat less, they take in less POPs. Also, these chemicals accumulate in an animals' fat. As Arctic char have very little fat compared to sea mammals, their flesh contains far less contaminants.

From the 1990s to 2010s, NCP researchers worked with communities across the North to measure POPs in sea-run Arctic char.³⁵ They found that concentrations were very low, even at Cambridge Bay and Saglek, in Nunatsiavut, and where there had been DEW Line sites. These sites had been contaminated with PCBs and later cleaned up. POPs are also declining in landlocked Arctic char in lakes on Cornwallis and Ellesmere islands.³⁶

Northerners are also concerned about another pollutant, mercury. Mercury occurs naturally in rock, soil, water, and air, and in plants and animals. Human activities like mining and hydro dams can cause it to increase. Like POPs, mercury levels increase with each step in the food chain. This means that fish feeding at the top of food chains (often on other fish) have higher mercury levels than fish feeding lower on the food chain (often on insects or shrimps).

Because sea-run Arctic char grow relatively quickly and feed mostly in the ocean, they tend to have low mercury concentrations. The Canadian Food Inspection Agency (CFIA) measured mercury in char at 35 sites across the North from 1975 to 1994.³⁷ The amounts were very low, averaging 0.05 parts per million – ten times below the amounts allowed by commercial sale guidelines. More recent studies, from 2004 to 2013, confirmed these low levels.³⁸

Scientists have measured mercury in freshwater resident and landlocked Arctic char.^{39, 40} Landlocked and resident Arctic char are more likely to have more mercury than sea-run char. This is because fish remaining in freshwater grow more slowly than sea-run fish and because there is more mercury in freshwater food webs than marine food.^20,

The amount of mercury in Arctic char can change over time. Many factors affect this, including the size of the fish, its condition (how heavy it is for its length), how quickly it grows, and the air temperature. Warming in the western Canadian Arctic has caused sea-run Arctic char to grow faster and their condition has improved in some regions.¹⁸ This tends to result in lower mercury levels. Labrador has been warming as well, but researchers have not observed declines in mercury in landlocked and sea-run Arctic char there.⁴² Changes over time can also differ among lakes, as smaller lakes can have more mercury than larger ones. Scientists have seen this on Cornwallis Island near Resolute.

Therefore, climate warming may affect mercury levels in Arctic char. Whether the levels increase or decrease depends on many factors. Landlocked and resident fish from smaller lakes are more likely than sea-run char to have levels of mercury above the guidelines for human consumption. Sea-run Arctic char continue to have very low concentrations of mercury.

Parasites are another important indicator of fish quality and their diet. Arctic char can pick up parasites from birds, invertebrates, and other fish. Where the char live (ocean and freshwater) also has an influence. Several different kinds of parasites can infect char. Some are large enough to be visible to the naked eye – such as tapeworm in guts, cysts attached to organs or flesh, worms in the swim bladder, and parasitic copepods on the gills or mouth.

The tapeworm is the only parasite that humans can get from Arctic char.⁴³ This can only happen by eating uncooked meat with cysts that contain larvae. Medication can treat this safely and effectively.

Climate change will probably impact the numbers and kinds of parasites in Arctic char habitats, and their ability to infect char. More research is needed to improve understanding of the parasites that infect Arctic char now, and how climate change may affect them in the future.

Species interactions

Some subarctic fish species are responding to climate change by shifting northward as waters warm.^{44, 45} These fish are appearing in subsistence nets across the Arctic.⁴⁶ We do not know much about how subarctic fish are interacting with Arctic char and other Arctic fishes. They may be interacting if they are in the same areas at the same time and if they need similar habitats and food.

Some species, like salmon, spend time in the ocean during summer and spawn in rivers and lakes in the fall, similar to Arctic char and Dolly Varden. For spawning, salmon need places, usually in rivers, that do not freeze to the bottom and that stay warm enough for eggs and juveniles to survive the winter. In the Arctic, these places are usually near groundwater springs. Arctic fishes also use these habitats, so it is possible that salmon and char could interact in both freshwater and marine environments. Researchers are working to understand better how salmon affect Arctic ecosystems and fishes.

In recent years, more salmon are being caught across the Canadian Arctic in subsistence nets set for Arctic char and other fishes.^{30, 47, 48} "Arctic Salmon" is a community-based program in the Northwest Territories that is monitoring this in the Mackenzie River and its tributaries (see http://www.facebook.com/arcticsalmon and http://www.arcticsalmon.ca). While there is a long history of Chum Salmon harvests in the Mackenzie River, they are being caught in more places and in greater numbers, especially over the last 10 years.^{47, 48}

Pink and Sockeye salmon have also been turning up in nets in recent years, especially in the Beaufort Sea communities. Fishers are catching Sockeye and Pink salmon as far east as Cambridge Bay.^{46, 47} Pink Salmon have occasionally been caught elsewhere in Nunavut, in Nunavik, and in Greenland.^{30, 46, 49}

Chinook and Coho salmon have appeared in nets in the Northwest Territories, although rarely. Subsistence fisheries in Nunavut also catch the occasional Atlantic Salmon.⁵⁰ Scientists expect these fish salmon species to shift northward, possibly impacting southern populations of Arctic char.^{51, 52}

There is an area in Nunavik where the northern range of Atlantic Salmon and the southern range of Arctic char overlap.⁵⁰ However, the spawning adults and young fish of each species prefer different freshwater areas. Atlantic Salmon generally spawn in rivers, while Arctic char spawn in lakes. Juvenile Atlantic salmon prefer faster water flows, whereas juvenile Arctic char prefer slower waters and pools.⁵⁰ It is possible that Arctic char feed on Atlantic Salmon eggs

Arctic char and Atlantic Salmon do have some similar temperature and habitat preferences, so they may be interacting. To understand this better we need more information on what habitats are available to them, especially in winter.⁵⁰

By assessing locations where the species are normally together, we can learn how northern fishes and southern fishes moving north may interact, and what the effects may be. For instance, both Dolly Varden and Pacific Salmon currently occupy streams in Western Alaska. There, Chum Salmon spawn further downstream, while Dolly Varden spawn further upstream in colder waters near groundwater sources.⁵¹ Salmon benefit Dolly Varden in those locations by adding nutrients to the system and food in the form of eggs and carcasses of spawned salmon, as well as juvenile salmon in both the freshwater⁵² and in the estuaries. More salmon are being seen along the Alaskan North Slope.⁵³ Warming temperatures may also be improving Pink Salmon production in rivers flowing into the northern Bering Sea.⁵⁴ This may mean that more Pacific salmon could move into the Canadian Arctic.

Indigenous Knowledge

The following provides an Indigenous Knowledge perspective on the issues discussed above through interviews and discussions with George Lyall of Nain, Nunatsiavut, NL, Norman Mike of Pangnirtung, NU, and Laurent Kringayark of Naujaat, NU.

The importance of char

Char is an important source of food for Indigenous communities across the Canadian Arctic. Inuit fish char for personal and commercial purposes when weather and ice thickness permit. In the past, Inuit did not fish much in winter, but better technology, such as nets, has meant that fish can be caught at any time of year.

People fish with rods or nets, from the shore, by boat, or through the ice. The catch is shared widely, as sharing food is part of Inuit culture. The tail goes to the children because it has fewer bones; the middle of the fish goes to adults because it is where all the strength is; and the head goes to elders as this is where the stories are.

In Pangnirtung, Nunavut, char has become the main source of country food. Many people who grew up eating caribou or seal are now eating much more fish. Naujaat, also in Nunavut, has a commercial char quota, but it is never filled. Commercial char fishing is seen as a viable livelihood in places where char are increasing, and a way to provide fish to people who could not get it otherwise.

Life of char

Where a char lives and migrates affects it in several ways, including its colour and condition. The skin and flesh colour may vary from deep red, to orange, to yellow, to white. Most people prefer to eat red or deep orange char, although most agree that the colour alone does not determine the taste. Landlocked or freshwater resident char can also be a different colour, but generally taste the same, though some people may prefer sea run ocean caught char.

Most char migrate from a lake to the ocean and back using the same river. However, around Voisey's Bay, Nunatsiavut, the char swim to the ocean in one river and return by another. Char can live up to 27 years. Older char stop going to the ocean.

It has been observed around Pangnirtung that male fish, ivashaluk, appear to protect the eggs in the riverbeds where the females have spawned. There are still male char in the lakes once the females have gone to the ocean.

Scars are common on char and are generally caused by lice, birds, seals, polar bears (and black bear in Nunatsiavut) or even dolphins who tried to catch them. Parasites have always been common in fish. People generally do not eat fish with a lot of parasites or even feed them to dogs. Landlocked char have more parasites than those that go to the ocean.

Testing for mercury in Naujaat and Pangnirtung has not caused concern, but in Nunatsiavut there is concern about mercury caused by dams.

Climate change and habitat change

Climate change is impacting the marine environment. Freeze-up is later, and ice is thinner and breaks up sooner. This affects the timing and safety of travel on ice to monitor and catch fish.

In recent years, people in Nunatsiavut have observed that fish are getting smaller. Some blame climate change, but no one is certain. They have also noticed that fish are not venturing as far into the ocean and staying near the coast.

While it is now harder to catch fish in winter, more fish are being caught during the longer ice-free season in many places. Capelin are more abundant around Pangnirtung. Char now feed on these and as a result their colour has changed from orange to a whiter shade. Capelin is a new species in the area; Cod, Tom Cod, sculpins, and lump fish are more typical. Salmon, maybe Chinook, are sometimes seen beyond Cumberland Sound.

Pangnirtung has also been experiencing other changes. Ocean water warming from the bottom up and melting permafrost are affecting the levels of rivers or changing lakes. Winds have also changed. East winds, which bring snow, are less frequent. Now winds blow more from the north, and these are dry winds with less snow. New lakes have been forming from melting glaciers; perhaps these new lakes could soon contain char

Emerging issues and knowledge gaps

Despite significant advances in understanding Arctic char habitat use, behaviour, and diet, many questions remain that could be addressed jointly through collaborative research by Western science and Indigenous Knowledge. First, regarding Arctic char habitat use, it will be important to do additional long-term studies on ocean habitat use to help understand how year-to-year changes in environmental conditions influence Arctic char behaviour in the ocean as marine waters continue to warm. These studies could shed light on why char often inhabit estuaries, which remains a question to be fully answered. Second, in terms of Arctic char diet, there is a need to continue to monitor what char eat in the ocean and whether this is changing due to shifting environmental conditions. Most importantly to communities, we need to assess if changes in char diet, for instance toward subarctic prey, may influence fish quality such as flesh colour, nutrients, and fat content. Conclusive data on this question are not currently available but will be important to understand how changes in char diet may influence food security and health in northern communities. Third, on contaminants in Arctic char and other qualityrelated issues, a critical research question to tackle will be to study the effects of climate warming on mercury bioaccumulation and levels in char. Furthermore, trends in the presence of parasites and the emergence of new ones remain a knowledge gap to address. Climate change will likely impact parasite dynamics and susceptibility of Arctic char to infections, as well as introduce new parasites through range expansions or introduced species. However, more research is needed to better understand current parasites in Arctic char populations, their prevalence in Inuit Nunangat, the potential influence of climate change on current and new parasites in fish, and the potential risks to human health. This knowledge will be critical to guide public health awareness and responses. In addition, contaminants of emerging concern, such as microplastics, should also be tracked more closely to understand their potential levels in Arctic char. Fourth, on species interactions, continued monitoring of subarctic species expanding their range should continue, as well as research on their interactions with Arctic species including Arctic char. In particular, the potential interactions between salmon species and Arctic char remain an important knowledge gap to tackle, such as studying habitat availability, including in winter, for the two species and whether habitat use may overlap. Overall, continued research on a range of monitoring needs and knowledge gaps — including, but not limited to, char response to climatic changes, parasite dynamics, trends in mercury over time and between different lakes, and new species coming in — will help support communities and organizations of Inuit Nunangat adapt management and policies around Arctic char.

Concluding remarks toward bridging different ways of knowing

We have learned much about Arctic char habitat use, behaviour, and diet, but many questions remain. How will char respond to climate change? Why do they prefer estuaries? How do changes in parasite populations affect them? What are the trends in mercury over time, and how do the differences between lakes influence the fish? It is essential to keep monitoring contaminants and other food safety issues to make sure Arctic char remains safe to eat.

The rapidly changing Arctic challenges our knowledge of Arctic char with new questions, complexities, and uncertainties. We know that temperature is among the most important factors shaping Arctic char distributions and habitat use, and it also affects fish health and metabolism. Changing Arctic conditions will likely affect Arctic char and other fish in many ways, with potential implications for community fisheries and food security (see Table 1). Knowledge holders in communities across the North are already seeing changes (see Indigenous Knowledge summary). For example, longer ice-free periods could mean longer and better feeding opportunities for Arctic char in the ocean – but these conditions could also make their upstream migrations more difficult. At the same time, longer ice-free periods and thinner ice affect the timing and safety of travel to fishing areas. In Nunatsiavut people are noticing that fish have been smaller over the past few years. Warmer waters also bring new (or more) potential competitors like Pacific and Atlantic salmon, and Lake Trout, as well as new (or more) prey. Communities are monitoring these new arrivals, but it is still unclear how they are affecting Arctic char and other Arctic species. People have already noticed that Arctic char flesh becomes paler when char eat more Capelin.

We need to understand how these and other factors will influence the abundance, accessibility, quality, and stability of Arctic char stocks, now and in the future. Through strong and equitable partnerships between researchers, communities, and Indigenous Knowledge holders, we will gain that understanding.

Table 1 Summary of ecological and biological information on Arctic char discussed in this paper and how these relate to the four pillars (Availability, Access, Quality, Safety and Stability) of food security. Also highlighted are Indigenous Knowledge insights on each of the pillars and how the ecology of Arctic char and food security may be altered under changing climatic conditions.

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Further Reading

• Bodaly, R.A., Jansen, W.A., Majewski, A.R., Fudge, R.J.P., Strange, N.E., Derksen, A.J. and D.J. Green. 2007. Postimpoundment time course of increased mercury concentrations in fish in hydroelectric reservoirs of northern Manitoba, Canada. Archives of Environmental Contamination and Toxicology, 53:379-389.
• Bond, M.H., Miller, J.A. and Quinn, T.P. 2015. Beyond dichotomous life histories in partially migrating populations: cessation of anadromy in a long-lived fish. J. Fish. Biol., 96(7):1899-1910. doi.org/10.1890/14-1551.1.
• Chételat, J., Amyot, M., Arp, P., Blais, J.M., Depew, D., Emmerton, C.A., Evans, M., Gamberg, M., Gantner, N., Girard, C., Graydon, J., Kirk, J., Lean, D., Lehnherr, I., Muir, D., Nasr, M., Poulain, A.J., Power, M., Roach, P., Stern, G., Swanson, H. and van der Velden, S. 2015. Mercury in freshwater ecosystems of the Canadian Arctic: Recent advances on its cycling and fate. Science of the Total Environment, 509-510:41-66.
• Chételat, J., Shao, Y., Richardson, M.C., MacMillan, G.A., Amyot, M., Drevnick, P.E., Gill, H., Kock, G., and Muir, D.C.G.. 2021. Diet influences on growth and mercury concentrations of two salmonid species from lakes in the eastern Canadian Arctic. Environmental Pollution 268:115820.
• Dunmall, K.M., Mochnacz, N.J., Zimmerman, C.E., Lean, C. and Reist, J.D. 2016. Using thermal limits to assess establishment of fish dispersing to high-latitude and highelevation watersheds. Can J Fish Aquat Sci, 73:1750-1758. doi:10.1139/cjfas-2016-0051.
• Gantner, N., Veillette, J., Michaud, W.K., Bajno, R., Muir, D., Vincent, W.F., Power, M., Dixon, B., Reist, J.D., Usmann, S.H. and Pienitz, R. 2012. Physical and Biological Factors Affecting Mercury and Perfluorinated Contaminants in Arctic Char (Salvelinus alpinus) of Pingualuit Crater Lake (Nunavik, Canada). Arctic, 65:195-206.
• Gantner, N., Power, M., Babaluk, J.A., Reist, J.D., Köck, G., Lockhart, L.W., Solomon, K.R. and Muir, D.C.G. 2009. Temporal trends of mercury, cesium, potassium, selenium, and thallium in Arctic char (Salvelinus alpinus) from Lake Hazen, Nunavut, Canada: Effects of trophic position, size, and age. Environmental Toxicology and Chemistry, 28:254- 263.
• Kortsch, S., Primicerio, R., Fossheim, M., Dolgov, A.V. and Aschan, M. 2015. Climate change alters the structure of arctic marine food webs due to poleward shifts of boreal generalists. Proceedings of the Royal Society B: Biological Sciences, 282: 20151546. Available at: https://doi.org/10.1098/rspb.2015.1546.
• Harwood, L.A. 2009. Status of anadromous Arctic charr (Salvelinus alpinus) of the Hornaday River, Northwest Territories, as assessed through harvest-based sampling of the subsistence fishery, August-September 1990-2007. 2890, Central and Arctic Region, Fisheries and Oceans Canada, Yellowknife, NT.
• Harwood, L.A., Sandstrom, S.J. and Linn, E. 2009. Status of anadromous Dolly Varden (Salvelinus malma) of the Rat River, Northwest Territories, as assessed through sampling of the subsistence fishery (1995-2007). 2891, Central and Arctic Region Fisheries and Oceans Canada, Yellowknife, NT.
• Martyniuk, M.A.C., Couture, P., Tran, L., Beaupré, L. and Power, M. 2020. Seasonal variation of total mercury and condition indices of Arctic charr (Salvelinus alpinus) in Northern Québec, Canada. Science of the Total Environment, p. 738.
• Swanson, H.K., Kidd, K.A. and Reist, J.D. 2011b. Quantifying importance of marine prey in the diets of two partially anadromous fishes. Canadian Journal of Fisheries and Aquatic Sciences, 68:2020-2028.
• Fereidoon, S., Synowiecki, J. and Penney, R.W. 1993. Pigmentation of Artic Char (Salvelinus Alpinus) by Dietary Carotenoids. Journal of Aquatic Food Product Technology, 2(1):99-115. Available at: https://doi.org/10.1300/J030v02n01_08.
• Swanson, H.K. and Kidd, K.A. 2010. Mercury Concentrations in Arctic Food Fishes Reflect the Presence of Anadromous Arctic Charr (Salvelinus alpinus), Species, and Life History. Environmental Science and Technology, 44:3286-3292.
• Swanson, H.K., Kidd, K.A. and Reist, J.D. 2010. Effects of Partially Anadromous Arctic Charr (Salvelinus alpinus) Populations on Ecology of Coastal Arctic Lakes. Ecosystems, 13:261-274.