By Noel Alfonso
Canada’s national identity is firmly bound to the Arctic. Inuit and Inuvialuit have lived in the Arctic for millennia and later European exploration provokes ongoing and intense interest. Canada also possesses the longest Arctic coastline in the world, with the Arctic Ocean having huge swings in environmental conditions. These range from bone-chilling temperatures in the dark winter to almost 24-hour sun and, in the lengthening days of spring, an explosion of life above and below the water.
My role as an ichthyologist (fish specialist) at the Canadian Museum of Nature is to understand and document the diversity of the fish that ply these Arctic waters. In fact, there are more than 217 species, a number that may surprise many whose knowledge of Arctic fish is limited to species such as Arctic Char and Greenland Halibut.
Some fascinating fishes are found in the Arctic environment—from sharks and rays, to deepwater residents, to rarely seen species that look like science fiction monsters, and some that even glow in the dark. Their diversity is amazing, especially given the unforgiving environment in which they live. Major groups include the aforementioned sharks and rays, as well as gulpers, herring, tube shoulders, salmonids (i.e. Arctic Char and Dolly Varden), dragonfishes, lanternfishes, sculpins, snailfishes, eelpouts, gunnels, wolffishes, sand lances and flatfishes.
The classification and interrelationships of all these fishes fascinate me in my job at the museum, where I can draw upon the world’s single foremost collection of Arctic fishes developed over more than 50 years. I am one of the contributors to a new field guide, Arctic Marine Fishes of Canada, which is in development by the museum and will, for the first time, provide detailed information on all Canadian Arctic fish species.
The majority of deep sea fishes are rarely seen by people unless they are lucky enough to be on scientific research cruises. They include wonderful and bizarre species like gulpers, hatchetfishes and dragonfishes. These tough and formidable creatures live year-round with their bodies chilled to near 0°C.
Some of these species create light — what’s known as bioluminescence. These fishes use bright lures to attract prey and patches of light on their bodies to signal to potential mates or to confuse predators. Tube shoulders, for example, are small (30 centimetres) fish that have large eyes to detect any bits of light in the deep sea. Five of the 13 species in Canada are found in the Arctic and they get their common name from a unique feature — a gland that produces a luminescent green-blue fluid that is excreted backward from a pore on each shoulder, thus confusing predators that are attacking from behind.
Fish species are usually adapted to specific environmental conditions, and the large area of the Arctic provides a number of distinct marine regions or ecozones. There are several oceanographic areas — each with its distinct profile of water temperatures, ice cover and nutrient flow. These range from the Eastern Arctic where the cold Labrador Current meets warmer waters from the Gulf Stream and the St. Lawrence River, to the Arctic Archipelago, where the short summer season causes the ice to melt and partially break up. The Arctic Basin is permanently frozen, and the ice cover rotates slowly around the North Pole in a counter-clockwise fashion.
Within these larger areas and located at either end of the country are two highly distinct areas for fishes and other marine life. They differ in terms of temperature and salinity and, not surprisingly, have very distinct fish faunas. In the extreme extent of the Northwest Atlantic, for example, Davis Strait and Baffin Bay form a unique habitat due to warm ocean currents to the east, cold currents to the west and huge differences in depth, ranging from 100 to 2,300 metres.
To the west, the Beaufort Sea borders the Arctic Archipelago. A shallow shelf extends 80 to 200 kilometres offshore with average water depths of only 50 metres. The inshore consists of lagoons, bays and estuaries which provide ideal habitat for a variety of species that are almost completely different from those in the Baffin Bay/Labrador Sea area. Because of wind-driven upwelling and plankton capture, the Beaufort Sea is a highly productive shallow habitat for species such as the Arctic Flounder, which is typically found in mudbottomed coastal waters and river mouths.
Ideally, it would be fantastic to present portraits of all 217 species, but I will limit this overview to just four species that are either well known, important to people or of high ecological importance.
Inuit and Inuvialuit peoples have eaten Arctic Char since time immemorial. Other fish species are also eaten, but to much less a degree. In the western Arctic Inuvialuit community of Sachs Harbour, people catch Arctic Cod off sea-ice in early summer, and set gill nets for Arctic Char, Arctic Cod and Least Cisco in late summer. In Cumberland Sound, Atlantic Cod and Greenland Halibut are also caught. Sculpins caught in tide pools have been eaten on occasion to avoid starvation.
The Arctic char is really the poster child for Arctic fishes. It is found throughout the Arctic, and not just in Canada. Important Arctic char subsistence fisheries are found all through their range, especially in the communities that border the Ungava and Hudson Bays, Baffin Island, Victoria and Banks Islands and the northern coast west of Hudson Bay and east of the Mackenzie Delta. In northern Quebec, Arctic char are second to caribou in the amount of country food eaten by Inuit. They are beautiful fish, being bright silver in the ocean, with highly variable colouration of greens, blues and red or pink spots with edges on some fins.
The Arctic has its own unique shark, the Greenland shark, which is widely distributed in the North Atlantic and the Arctic Ocean. This impressive animal reaches 7.3 metres and up to 1,000 kilograms.
Although it has been described as sluggish, it can be an active predator feeding upon seals and char. This shark also feeds on whales caught in nets, many bottom-dwelling fishes, jellyfishes, cephalopods, gastropods, crustaceans and sea birds. The Greenland shark is a scavenger that comes in to near shore areas and estuaries to feed upon carrion and offal discarded from whaling and fishing operations. It slowly and deliberately takes large chunks of flesh from a whale carcass. A whole caribou has even been found in a Greenland shark!
There were commercial fisheries in Greenland until the early 20th century and these sharks were caught to extract liver oil for lamp and machine oil. In northwestern Greenland they are still caught to feed sled dogs, but this species is caught as bycatch by trawlers and long-liners. Dried or boiled flesh was used to feed dogs, as the flesh is toxic when fresh. The skin has been used for sandpaper and boots, the tanned skins for leather and the lower tooth row for knives or saws.
Arctic Cod and Greenland Halibut
The two most important fish species in the ecology of the Arctic Ocean are the Arctic cod and Greenland halibut, the former found all through the Arctic Ocean and the latter mainly in the eastern Canadian Arctic. The Arctic cod is a keystone species because it provides the main link between phytoplankton and small crustaceans, and other fishes, seabirds, marine mammals, and terrestrial mammals. These small fish are often found in huge schools under the ice, where they feed among the lush algae and on the copepods and amphipods.
Greenland halibut is one of the top predators in the northwest Atlantic and the most abundant top predator since the collapse of the Northern Cod. They are caught in gill nets, trawls and long lines and sold as fresh-frozen fillets.
They are also smoked and salted for local use. Limitations to commercial harvest in the Arctic are lack of suitable equipment and infrastructure as well as transportation issues. The occurrence of Greenland halibut in deeper waters (up to 2,000 metres) means that specialized gear is necessary to catch them. Longlines are preferred in this fishery, as gill nets tend to catch primarily large mature females. There is also concern over the issue of bycatch of Greenland shark and the entanglement of marine mammals such as narwhals, bowhead whales and beluga. Lost gill nets can turn into “ghost” fishing nets, catching fishes and other species for years.
Many more Arctic fish species, of course, have intriguing stories and these will be profiled in the upcoming Arctic Marine Fishes of Canada guide.
For those able to visit the Canadian Museum of Nature in Ottawa, an innovative photo exhibit called X-Rays of Arctic Fishes is on display until September 2015. Get an “inside-out” perspective of 16 species of Canadian Arctic fish through evocative and haunting images, and gain a sense of wonder for these marine inhabitants of Canada’s Arctic waters.