Canada’s Oceans Now: Arctic Ecosystems 2023

© His Majesty the King in Right of Canada, as represented by the Minister of the Department of Fisheries and Oceans, 2025.
Cat. No. Fs23-549/1-2024E-PDF 978-0-660-73837-6

Acknowledgement

The knowledge shared in this report reflects an immense effort from researchers, technicians, ship crews, co-management boards, Hunters and Trappers Organizations, community members, and others. We appreciate the effort of Inuit organizations and scientific contributors who reviewed this report. We recognize the commitment of all those who seek to understand Arctic marine ecosystems. We gratefully acknowledge that much of the work presented in this report was undertaken within Inuit homelands (Inuit Nunangat), which includes lands, waters, ice, and all life within.

Thank You
Nakurmiik
ᖁᔭᓐᓇᒦᒃ
Quyanainni
Koana
Merci

Artwork by Amanda Key

Foreword

Canada’s Oceans Now reports are summaries of the current status and trends in Canada’s oceans. These reports are produced as part of the Government of Canada’s commitment to inform the public on the current state of Canada’s oceans.

Canada’s Oceans Now: Arctic Ecosystems, 2023 gives new knowledge about the state of marine ecosystems in the Canadian Arctic. The report was generated by a team of co-authors from Arctic communities and Inuit organizations, academia, non-government organizations, and Fisheries and Oceans Canada.

This report is based on information detailed in the Canadian Technical Report of Fisheries and Aquatic Sciences 3633, State of Canada’s Arctic Seas1. The information presented reflects improved ways of understanding and learning about Arctic marine ecosystems. The current status of the environment, habitats, species, and food webs is discussed. This report highlights advancements in knowledge of biodiversity (who is there), habitat conditions (how ecosystems are structured and used), and processes that affect habitat and species responses (why variability and change are occurring).

Learning Together

Researchers and northern Indigenous Peoples are working together to use existing information and advance new information needed to understand and manage ecosystems in the Canadian Arctic.

The Canadian Arctic encompasses Canada’s largest ocean area, stretching from James Bay to waters off the most northern point of Nunavut (Figure 1: Report study area and communities of Inuit Nunangat). This Arctic area covers a wide range of coastal and offshore environments. Many locations have not been studied, and there continues to be much to learn about Arctic marine species, habitats, and ecosystem processes. Inuit across Inuit Nunangat and researchers are increasingly working together to identify and address ecosystem questions. The state of recorded knowledge varies greatly across the Canadian Arctic. It is important to know where in the Arctic the information comes from and what time of year it describes. Arctic-wide generalizations tend to be inaccurate, and are unlikely to be helpful in decision making. Through multi-year observations, we can better understand the amount and type of variability happening in the ecosystem, and identify climate-driven changes.

Spotlight: Inuit Nunangat

Inuit homelands are called Inuit Nunangat and include the lands, waters, ice, and all life within. Inuit Nunangat is comprised of four Inuit regions: Nunavut, Nunavik, Nunatsiavut, and the Inuvialuit Settlement Region.

Extreme conditions in the Arctic make it challenging to conduct scientific research and monitoring year-round. Most research occurs when there is open water (about July to September). This is when sites can be reached by boat and ship. Yet, the use of new technologies and continuous observations (e.g., using ocean moorings) increase knowledge of ecosystems, including species biodiversity and distributions throughout the year. Winter community-led monitoring can provide documented information in an often data-poor season. The use of new sound (i.e., acoustic) and satellite (i.e., telemetry) survey technologies improved mapping of animal movements and their population over seasons (e.g., community-based beluga telemetry program and cooperative interpretation of results).

The participation of Indigenous communities in scientific research and monitoring is growing with efforts to bridge Indigenous Knowledge and Western science data (Figure 2: Scientific research and Indigenous Knowledge). While many research projects provide information about current changes, Indigenous Knowledge provides the longest perspective over time. Partnerships characterized by mutual respect and collaboration build an understanding of historical environmental and biological baseline conditions, which helps identify and monitor changes. Bridging multiple ways of knowing builds a fuller understanding of environmental change. This is critical for effective co-management of marine species and ecosystems in Inuit Nunangat.

Connected, yet Different

Canada’s Arctic has areas with unique sea ice and ocean conditions, despite strong influences from the Pacific, Atlantic, and Central Arctic Oceans.

Sea ice and ocean trends in the Canadian Arctic can be influenced by connected oceans, but remain unique. Datasets over 20 years and longer are critical to identify and understand changes and differences between ocean areas. Long-term scientific sea-ice trends come primarily from satellite data analysis (from 1979 to today). Satellites can also reveal conditions like temperature and algae concentration, but only at the ocean surface. Ocean trends discussed below are identified by ship-based measurements repeated each summer (i.e., the Beaufort Gyre information) and/or by ocean moorings. Long-term moorings are underwater lines of instruments that collect ocean data such as temperature, salinity, water motion, and ice thickness all year long. They are replaced each year to continue recording data. In the entire Canadian Arctic, fewer than seven moorings have measured ocean conditions continuously for more than 20 years.

In the Northern Hemisphere as a whole, sea ice extent has declined in all seasons, and the open-water period has increased in areas that have ice cover only in winter (Figure 3: Sea ice changes). Summertime ice volume has declined by as much as 82% between 1979 and 2023 for the Arctic as a whole. This major decline in ice volume reflects the significant loss of the thick multi-year sea ice (Spotlight: Types of Sea Ice). This loss is not the same in every area of the Arctic. Canadian waters continue to harbour multi-year ice habitat. Over the last 10 summers, multi-year sea ice has declined by 7% in the northernmost area of the Canadian Arctic (Figure 4: Types of sea ice). Gradual changes in sea ice can be seen. There are also years and decades that have rapid, strong decreases or increases.

Ocean areas are directly connected, yet unique areas are known. This includes the Beaufort Gyre which is a spinning, offshore ocean area that spans the deep Canada Basin in the western Canadian Arctic (Figure 4: The Beaufort Gyre). The continental shelf is influenced by the Beaufort Gyre that connects to it. Studies since 2003 have tracked an accumulation of fresh water in the few hundred metres at the top of this gyre and an accumulation of heat in the sub-surface layer of water coming from the Pacific. This build-up happened over 26 years when the Beaufort Gyre spun counterclockwise more rapidly (Figure 4: The Beaufort Gyre). The added weight of fresh water on top of the gyre pushes the lower Pacific layer of water up (an upwelling) and onto the shallower continental shelf of the western Canadian Arctic. This movement of saltier water toward shore was monitored for 30 years by mooring instruments near the seafloor on the continental shelf. Such a long data collection was needed to detect this change with certainty.

Dynamic ocean habitat is created by variability and change in both offshore and coastal waters. Temperature and salinity are key factors controlling the structure and suitability of ocean habitat for life. The small amounts of change measured in seawater of the western and eastern Canadian Arctic (Figure 5: Canadian Arctic inflow and outflow) are different from the larger changes observed over the same years in the Bering and Barents Seas. These other Arctic seas are receiving warmer waters from their neighbouring oceans.

Updating Expectations

New research shows there are some inconsistent and unexpected ways that marine ecosystems respond to natural variability or climate change.

New information has shown complex and sometimes unexpected responses of marine ecosystems to ocean variability or climate change. Unexpected ocean dynamics and species distribution are identified over time and across southern to northern locations.

Benefits from sea ice loss?

Shipping through Canada’s Northwest Passage was expected to be easier with sea ice loss. However, comparing 1968-2006 and 2007-2020 showed that even with less multi-year ice (presence and growth) in the Northwest Passage, it will continue to be a shipping hazard for the foreseeable future. Expanded habitat for kelp and seagrass was also expected because of ice loss and other climate-related environmental changes, but expanded habitat has not yet been detected at the few Canadian sites with at least 10 years of data. Recent surveys of James Bay eelgrass affected by hydroelectric development and extremely warm 1990s conditions show ongoing loss. This also contradicts the current climate-related expansion of eelgrass habitat in other parts of the Arctic. In Canada, some potential opportunities from sea ice loss and Arctic warming are not necessarily quick or guaranteed.

Neighbours but different

Even in adjacent areas, we see changes that are not necessarily the same. Changes in zooplankton biodiversity have been documented in the Pacific and Atlantic Oceans. However, despite a strong connection to those waters, such changes have not been detected in the Canadian Arctic. The North Water and Lancaster Sound ice arches (Figure 3: Sea ice changes) are only a few hundred kilometres apart in the eastern Arctic. These ice arches are critical for polynya formation (Spotlight: Polynyas). The number of days each year that the arches were stable stayed similar for 20 years, and then in 2001-2022 their instability patterns changed . They are not responding the same way to forces from the atmosphere or ocean.

Large-scale comparisons

At a larger scale, trends across oceans and across the Canadian Arctic have not matched predictions. A recent study of seafloor biodiversity found that the Canadian Arctic Ocean has a higher diversity of seafloor invertebrates than Canadian Atlantic and Pacific waters do. This contradicts the widespread assumption that biodiversity declines the farther north one looks. Species important for the food web show some consistent trends in diversity and biomass, including zooplankton and Arctic cod. This consistency is unexpected in many marine ecosystems, especially given ongoing climate change impacts. In offshore waters, the composition of zooplankton communities is consistent across the entire Canadian Arctic, including Hudson Bay. The communities are all dominated by energy-rich species of copepods. Recent ship-based measurements (hydroacoustics) in offshore habitats across the entire Canadian Arctic also indicate stable trends in Arctic cod biomass. However, variability from one year to the next shows that the timing of sea ice break-up can influence Arctic cod biomass, especially in Baffin Bay.

Other rare ocean conditions can be identified when the Canadian Arctic is compared to other Arctic regions or world oceans. This includes conditions related to ocean chemistry (Spotlight: Ocean Acidification Extremes) and the presence of old, thick sea ice in the Tuvaijuittuq Marine Protected Area north of Ellesmere Island. There is more old sea ice in that area than anywhere else in the entire Arctic (Figure 3: Sea ice changes).

No ocean warming trend was found in the Eastern Beaufort Sea, according to satellite data of summer sea-surface temperatures (2003-2019). That finding seems uncommon or counter-intuitive, given that Arctic air temperatures are rapidly warming. Still, important change did occur. The surface waters warmed significantly earlier in the year, over the time studied. That affected the amount and timing of phytoplankton growth. This example demonstrates that assessing a single trend may not verify whether ecosystem change is happening or not. A trend may also go undetected because there is not enough data for many parts of the marine ecosystem.

Source or sink? - No one answer

The issue of data availability is particularly important for understanding how oceans interact with carbon dioxide (CO₂) in the atmosphere. Oceans are critical for controlling CO₂ levels in the atmosphere to stabilize the climate. Is Canada’s Arctic Ocean a CO₂ sink or a source of CO₂? If it is a sink, the CO₂ moves from the atmosphere into the ocean. If it is a source, the CO₂ is released from the ocean into the atmosphere. Improved data coverage reduced uncertainty in answering this question. The new data highlights how the answer depends on the season and on the physical structure of the ocean (Figure 6: Source or sink: CO₂ in Arctic waters).

How Species Respond

New studies have led to a better understanding of how ocean habitat varies over seasons and years, and how that makes opportunities or challenges for some species.

Marine life is intimately connected to yearly cycles of habitat change including ice cover and open water, darkness and light, warming and cooling, and pulses of production that fuel the food webs. Long natural cycles (e.g., 10 years) and climate change can alter the

• sea ice and ocean layer habitat
• chemistry and energy sources (nutrients) of the habitat
• timing and connections between ocean and atmospheric processes, and between freshwater and marine habitats

Habitat variability and change can influence the distribution of resources for species, when and how many offspring they have, how they feed and hunt, and where they go. Recent research showed that some species might adapt to habitat changes, at least in the short term.

Warming: Ice and river habitat change

Algae growing on the bottom of sea ice is an important early food source. Many zooplankton, small invertebrates and fish can eat the ice algae as it grows. When the snow and ice melt, the algae released from the ice can be quickly eaten by grazers in the water and by invertebrates on the seafloor. With changing sea-ice habitat, the availability of ice algae will also change. Zooplankton and seafloor invertebrates do eat a variety of things, but it is not known how having less access to ice algae will affect the quality or diversity of seafloor invertebrates.

It is also hard to predict how habitat change caused by warming will affect culturally important species such as Arctic char (Spotlight: Arctic char, did you know?). Different responses could be seen among individuals and whole populations as their environment changes in multiple ways (Figure 7: Responses of Arctic Char to habitat change). Sea ice change will continue to affect all marine habitats and links between food webs. Warming will also impact the suitability of habitat for species and overall biodiversity.

Responses: Genetics and mobility matters

Low genetic diversity within a species can make that species less able to adapt to habitat change, especially if they cannot move to a different location. For example, eelgrass in James Bay has less genetic variability than eelgrass in the Canadian Pacific and Atlantic sub-Arctic. With low genetic diversity, the James Bay eelgrass has limited potential to adapt to habitat changes linked with warming, earlier ice break-up, and increased freshwater input.

In contrast, mobile species have more options to cope with habitat change. Some populations of beluga and bowhead whales have adjusted the way they dive to reach prey. Dive behaviour also changes in response to location within their range, time of year, and the amount of sea ice around them (Figure 8: Diving in: learning about marine mammal habitat use). Narwhal, once thought to be less flexible than other whales when migrating, have now been observed to delay their fall migration south because there is less sea ice in their habitat. In Hudson Bay, a colony of thick-billed murres shifted its habitat range to areas with less ice cover. These new areas still had cold enough waters for their prey that prefer an ice-covered habitat. Flexibility in habitat use, especially in seasons when they need fatty food, can help marine predators cope with the impacts of climate change in the Arctic.

Large-scale changes to migratory patterns have not been seen in the Canadian Arctic, though marine mammals and seabirds have made local adjustments in response to habitat change. However, the presence of killer whales and sperm whales is increasing in the eastern Canadian Arctic. The whales can travel farther and stay in new areas because of sea ice loss and the longer open-water period.

Species Stability and Habitat Use

There is improved knowledge about where species live, which habitats they prefer, and the diversity of species that live in Canada’s Arctic waters.

New information actively describes the locations of species at different times and spatial scales. As we zoom into the Canadian Arctic, we consider three scales:

• Arctic-wide – can include connections between the Arctic and other oceans
• coastal – such as shoreline waters shallower than 20 m
• small – such as a metre of water within a phytoplankton bloom

Evaluations of different species show how they might affect their environments and how stable these species are.

Arctic-wide scale

Studies spanning the entire Canadian Arctic have updated the knowledge of species distribution and diversity. For example, at over 400 stations across the Canadian Arctic, the fatty zooplankton Calanus hyperboreous was found at 93% of the stations and Calanus glacialis was at 100%. Other smaller copepods (e.g., Oithonia similis) were also present at 93-100% of the stations (Figure 9: Relative size of some Arctic copepods). This means that important prey for marine fishes and bowhead whales are currently accessible throughout Canadian Arctic waters. At this Arctic-wide scale, the diversity of invertebrates living on and in the seafloor has also been re-evaluated. A recent study found 1552 different types (taxa) of invertebrates, which is 560 taxa more than found before. Yet, this new assessment probably still underestimates seafloor biodiversity. Much is being learned about marine mammal, fish, and bird distributions during their seasonal movements.

For marine mammals, water depth plays a key role in where whales gather and how they use habitats to feed (Figure 8: Diving in: learning about marine mammal habitat use). The migration of marine birds can be measured over long distances with satellite tracking, lightweight geolocators, and small GPS devices. New tracking of marine birds identified long-distance connections to Antarctica (Arctic terns), the Indian Ocean (long-tailed jaegers), the Sea of Okhotsk (glaucous gulls), the Gulf of Mexico (herring gulls), and multiple locations in the Pacific and Atlantic Oceans. Understanding these long-distance connections is necessary to examine the potential effects of large-scale environmental changes and human influences on both Arctic breeding grounds and more southern wintering grounds.

Coastal scale

In coastal areas, Indigenous Knowledge and community-led monitoring provides understanding of past and current species diversity and changes in marine mammal and fish distributions and health. In recent years, Arctic communities reported unusual species sightings. These sightings could show a gradual shift in a species’ range, a rare species, or a species arriving because of a drastic shift in the ocean environment (Figure 10: Community observations: tracking coastal biodiversity).

Applying multiple ways of knowing enhances the understanding of unusual sightings and unexpected events. Indigenous Knowledge of past and current species provides insights into which occurrences are rare and unusual, versus those that are actually new. Community-led observations provide a better understanding of sperm whale sightings in Eclipse Sound since 2014 and bowhead overwintering in new areas. The sperm whale and bowhead sightings are linked to sea-ice change observed by the communities.

In coastal areas, the habitat preferred by Arctic char and similar species (e.g., Dolly Varden) is tightly linked to water temperatures and salinity levels that best support physical performance (e.g., activity and digestion) and their prey. New information indicates that individual Arctic char can migrate within ice-covered rivers and to marine waters in winter. Fish from the Coppermine River moved up to 18 km offshore under the sea ice (Kitikmeot region of Nunavut) where some of the lowest Arctic char body temperatures were recorded. This previously undocumented winter movement shows that rivers can be important connections between freshwater and marine ecosystems year-round, not just after ice melt.

Small scale

At very small scales, hi-resolution underwater video (Spotlight: Marine Snow) revealed how and when individual phytoplankton cells begin sticking together into groups that then sink. This video technology showed that copepod zooplankton follow those groups, feeding on them rather than individual cells that stayed closer to the surface. This detailed description of species interactions helps to understand how and when energy is transferred at the base of the marine food web.

Impacts and stability

Some new knowledge about species suggests they could impact their ecosystem. Harmful algal blooms that led to toxins in seafloor invertebrates (i.e., amnesic and paralytic shellfish toxins) were found in the western Canadian Arctic. The toxin levels were very low, and those invertebrates are not harvested by local communities. It is not yet known if harmful algal blooms are becoming more common in the Canadian Arctic.

Communities keep monitoring salmon in the Canadian Arctic. The first capture of a juvenile chum salmon near the Canada/USA border (Kaktovik, Alaska) confirms spawning in the North American Arctic. Consequences and possible opportunities of more salmon in Arctic rivers remain uncertain for other fish and the people that depend on them.

There is not enough long-term population data to scientifically rank the conservation status of most marine species in Canada’s Arctic. Two species of marine birds are critically imperiled: the black guillemot and the ivory gull. For marine mammals, the most recent inventory was for Eastern Beaufort Sea beluga whales, which found a stable population of 38 000. Marine mammal population counts generally happen every 5 years, or longer, for a specific population. But every year, commercial fish and shrimp stocks are monitored in Baffin Bay, Davis Strait and eastern Hudson Strait. Those show healthy populations of Greenland halibut and northern and striped shrimps, although the increase in juvenile redfish (Spotlight: Redfish Resurgence) could threaten shrimp by eating them and competing for food.

Understanding How Ecosystems Work

There is now a deeper scientific understanding of how ecosystems work and what can influence the activity and survival of some marine species.

Understanding the many steps that cause change in the ocean is essential for ecosystem management. In recent years, interactions between species and the environment were investigated across food webs and regions. This led to better descriptions of expected responses to change.

Ecosystem controller: The Sun

The Sun and sea ice play a major role in controlling Arctic marine food webs. At some locations, the amount of daylight changes from none to all day during an Arctic year (Figure 11: Where can you find the midnight sun?). The food web’s response to the return of the Sun is fast. The transfer of sunlight through sea ice and into the ocean controls where and when ice algae and phytoplankton grow. Their growth provides the energy that supports most of the food web. Snow that falls on the ice can block the transfer of sunlight needed to start growth after the dark winter. New research from Baffin Bay shows that 100 times more light can pass through the ice in just two weeks once the snow begins to melt. The ocean surface habitat quickly comes to life under the remaining snow and ice. But if enough new snow falls, sunlight is blocked and the new growth stops suddenly. With enough sunlight, the phytoplankton population quickly grows, providing food for zooplankton.

Cycles of sunlight cause many Arctic zooplankton and fish to migrate up and down in the water column each day to avoid being seen by predators. They transfer food web energy with them as they move vertically. New research from the western Canadian Arctic showed that part of beluga migration is linked to cycles of sunlight. In the fall when the Sun once again sets in the evening, beluga show distinct sun-related movements in water deeper than 700 m: shallower dives when darker and deeper dives in bright daylight.

Ecosystem controller: Sea ice

What happens to marine ecosystems when the clearance of sea ice is early? Considering responses to an earlier clearance of sea ice is necessary to understand more about how sea ice controls ecosystems. This change creates a longer open-water period. Across the Arctic, earlier ice clearance was expected to increase production at the base of the food web and benefit all. But that increase at the base has not yet been clearly documented in the Canadian Arctic. Ice clearance that is too early could limit benefits, research shows. It now looks like ice break-up before June raises the chance that zooplankton larvae will miss the best time to feed (Figure 12: Ups and downs of cod and copepods). Consequently, fewer larvae develop into adults, and adult growth is low. This then reduces food for larval Arctic cod, limiting their development into adults. Ice-driven changes in the timing of food for zooplankton are not the only reason for a mismatch. Available food may not be healthy for the larvae. This occurred recently in Baffin Bay where the phytoplankton (Pseudo-nitzschia) appeared to release a toxin (neurotoxin domoic acid)that stopped the copepods from feeding, despite the good timing of the bloom (Figure 12: Ups and downs of cod and copepods).

Sea ice is changing across the Canadian Arctic (Figure 3: Sea ice changes), yet responses from one species can vary in different locations. In both Baffin Bay and the Beaufort Sea, the survival of larval Arctic cod into adulthood is affected by sea-ice concentration and water temperatures. In Baffin Bay, the timing of sea-ice break-up is strongly connected to the survival of Arctic cod larvae. The same strong connection is not found in the Beaufort Sea (western Canadian Arctic) even though the ice break-up has changed by a month or more (Figure 12: Ups and downs of cod and copepods).

Ecosystem controller: Nutrients

Nutrients (e.g., inorganic nitrogen, phosphorus, silica) provide the fuel for the base of the food web. How nutrients are distributed across the Canadian Arctic was recently studied, updating key understanding about nutrient supply. For example, it is now understood that waters originating from the Atlantic Ocean supply up to 25% of the nutrients to the Canadian Arctic Archipelago. The previous estimate was only 5%. In coastal areas, glacial meltwater brings nutrients to the northeastern Canadian Arctic in two ways: it directly supplies micronutrients such as iron and manganese, and its cold, dense meltwater sinks, pushing up water from the deep with nutrients that phytoplankton use (Figure 13: From the land: nutrients and carbon entering the ocean).

Organic carbon in the water is also a key marine nutrient. Two types of organic carbon are important for the food web. If this carbon is smaller than a speck of dust, it is called dissolved carbon. Microbes (e.g., bacteria) or pieces originally from a living organism represent the second type: particulate carbon. More is now understood about mechanisms controlling the supply of both carbon types from rivers, land, and the ocean. Rivers can supply large amounts of organic carbon to coastal and marine food webs. Long-term trends (e.g., 1998-2019) from the Mackenzie River area show a significant increase in both types of carbon in late summer. This is likely explained by inputs from thawing permafrost (Figure 13: From the land: nutrients and carbon entering the ocean). Consequently, thawing permafrost can be an important factor in understanding the transfer of carbon to the marine environment. The transferred carbon does not always stay in the dissolved or particle form; some of it is changed to CO₂. Slow-flowing permafrost debris has been found to release over three times more CO₂ to the atmosphere than the debris from a coastal cliff can when it suddenly collapses. The amount of CO₂ released by eroding permafrost depends on the type of erosion and how long debris stays close to shore.

Conclusion

Canada’s Oceans Now: Arctic Ecosystems, 2023 shares major advancements in the understanding of how marine ecosystems function and their status in Canada’s Arctic. New insights continue to highlight the importance of understanding physical environmental conditions and the base of the food web. This is needed to explain changes in species and how ecosystems function.

This report emphasizes that it is unwise to make general statements about a specific change or status indicator. To ensure the proper understanding of an issue, the specific place and time that it relates to should be taken into consideration. There continue to be significant gaps in knowledge as information is not equally available for all locations and communities. However, our collective understanding is improving with the respectful inclusion of multiple ways of knowing and the incorporation of different data collection methods and research from various disciplines. Collaborative programs continue to build new and better understandings of species and the ecosystems in which they live.