In late summer of 2019 a Salmon Shark (Family Lamnidae, Lamna ditropis) was caught in the maritime waters the the main Canadian Arctic (a few kilometers north of Kugluktuk). The Salmon Shark is generally a species found in temperate and also sub-arctic Pacific ocean waters, for this reason finding one in Arctic waters is fairly unusual. Right now this is being characterized as severe extra-limital occurrence. However, this isn"t the only instance of current changes emerging in the Canadian Arctic maritime ecosystem.

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Above: Salmon Shark (a types newly taped from the Arctic) by Kugluktuk resident, john Kapakatoak

Sharks space fusiform-bodied fishes with cartilaginous fairly than bony skeletons. Five types of shark are recorded as normally emerging in Canadian Arctic or sub-arctic naval waters - the Greenland Shark, Portuguese Shark, black color Dogfish and Deepsea Cat Shark. This are discovered in Davis Strait/Baffin only in the east Arctic. Just the Pacific Sleeper Shark is well-known to take place in the Canadian Beaufort Sea in the western Arctic.

These shark varieties are generally found in deep-water habitats throughout the open-water season, yet in winter may endeavor near coastlines on shallow shelves search food. This is especially true for the Greenland Shark, which have the right to be quite big (up to 6 m in length). Previous distributional records exist because that Greenland Shark in some places in east Hudson Bay, however, one individual was recorded at Coral Harbour in 2018 in northwestern Hudson Bay and also is the closest record to Manitoba waters for any kind of shark species.

A number of unusual events emerged in the Arctic in both 2018 and also 2019.

This year, one unprecedented number of Pacific salmon that various varieties were caught by indigenous fishers in countless locations the the western Arctic and also as far east as Kugluktuk. So far around 3000 samples have been rotate in come the Arctic Salmon project, which has been surveillance the increasing cases of salmon because 2000. That the five varieties of Pacific salmons that typically occur in temperate and sub-arctic waters of the west coastline of Canada and also Alaska, only one is recognized to have little reproducing populations in the Mackenzie River basin of the west Arctic. Till recently, the remaining four varieties were documented only together occasional vagrants (i.e., unexplained distributional occurrence) to Canadian Arctic waters.

Increased numbers of all species have been typically occurring, through high variations in numbers from year-to-year. 2019 was exceptional. Pacific salmons have likewise shown progressively enhancing distributions of occurrences in much more easterly waters that the Arctic Archipelago but, as yet, no brand-new colonizing populations have been observed.

So, what is happening? Like in other places in the country, Canada’s Arctic naval ecosystems appear to be undergoing substantive and relatively rapid changes. These alters likely include changed marine problems such together warming s waters, inexplicable shifts in activities of marine water masses, and also associated alters in the ecosystem structure (such as altered distributions and also occurrences of species not previously well-known from the area). These changes appear to it is in affecting the west Arctic much more substantively and also sooner than waters in the east.

The Canadian Beaufort Sea is normally consisted of of layers of water. Every layer originates from a different location and has various levels that salinity and different temperatures. In summer the optimal 50 meter is reasonably freshened sea-ice meltwater and also river runoff. Below this (between 50 and around 250 meter depths) the water layer originates from the north Pacific s (Bering Sea), and is reasonably warm, nutrient-rich and lower in salinity. Added water class exist in ~ deeper depths.

The two linked surface layers usually move eastwards throughout shallow sills into and through the passages of the Canadian Archipelago, ultimately exiting into Baffin Bay and also Davis Strait. These surface water currents connect areas of the phibìc Pacific come those of the Archipelago, and also ultimately the Northwest Atlantic. In concept they carry out a maritime ‘highway’ for fishes and other biota.

Different water class are desired habitats because that distinctly various groups that fish species. Pacific salmon and the Sleeper Shark favor the upper surface layers because of warmer temperature and far better feeding. Whereas adults of most Arctic species tend to like bottom areas in deeper waters. In recent years greater amounts of Pacific-origin water are entering the west Canadian Arctic, moving eastwards, and likely carrying plankton prey wanted by salmon. In turn, the salmon are complying with their prey and an in similar way the Salmon Shark is following its prey. Parallel shifts in the Arctic normally towards much less sea ice cream overall, warmer maritime waters in summer, and also greater pelagic (water column) productivity additionally appear to help these outcomes, more enhancing the suitability the Arctic waters because that at least some sub-Arctic fishes. This is thought to explain occurrences of increasing numbers of Pacific salmon over wide areas of the west and main Arctic, and in 2019 the Salmon Shark occurrence.

Climate variability and adjust is substantively transforming the Canadian Arctic maritime ecosystems, and is eventually the driving pressure behind these unexplained occurrences. Previously, 221 species of fishes consisting of the salmons were known to take place in Canadian Arctic naval waters and also the Salmon Shark rises this to 222. This number is expected to boost as added ecosystem shifts linked with climate adjust take host and additional sub-arctic fishes colonize the area.

Continued monitoring through Arctic Salmon and also other programs will certainly provide much more examples that these unexplained events and also lead to far better understanding that the changes occurring in Canada’s Arctic maritime system.

Resource sources for added information:Arctic Salmon – Fishes that the Canadian Arctic. 2018. B.W. Coad and also J.D. Reist (eds.). University of Toronto Press.

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About the author: Jim Reist is a researcher on ecology, diversity, adaptation, and also stressor responses (including responses come climate variability and change) the northern and Arctic fishes in Canada. That is interested in biodiversty, specifically that connected with the most speciose teams of invertebrates – the insects, and vertebrates – fishes. Nearing official retirement, he is resurrecting early interests in Lepidoptera (butterflies, skippers and moths), Odonata (damselflies, dragonflies) and Coleoptera (beetles) together a emphasis of activity.