Fisheries and Oceans Canada
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Seals and Science at Fisheries and Oceans Canada
There are six species of seals in Canada:
Among these, harp and grey seals are the subject of focused science efforts at DFO.
Harp Seals
Photo Credit: Mike Hammill
Size: Male and female harp seals are similar in size with adults averaging 1.6 m in length and weighing 130 -150 kg.
Feeding habits and impact on the ecosystem: Harp seals eat a varied diet of fish such as capelin, cod, herring, sculpin, Greenland halibut, redfish, and plaice. They also consume crustaceans, shrimps and prawns.
DFO has conducted numerous studies on seal interactions including two workshops held in 2007 and 2008, which evaluated the effects of seals on fish stocks. These results suggest that harp seal predation is not a significant factor in the lack of cod recovery to date, and that cod recovery is being affected by low productivity associated with low capelin. In the Gulf of St. Lawrence, relationships are not explicit. The lack of cod recovery seems mainly due to poor cod recruitment resulting from low spawner biomass (a consequence of fishing and predation). Studies show that predation by harp seals could affect recruitment, but this is less important than oceanographic conditions on recovery.
Reproduction and life cycle: Females bear a maximum of one pup per year, between late February and late March and require stable ice for giving birth and rearing their young. Newborn pups weigh around 11 kg and are 80–85 cm long. They are nursed, on average, for 12 days and gain over 2.2 kilograms per day. Once the pups are weaned, the females leave the ice to mate. The pups begin to moult their whitecoat at around 14 days old. By three weeks of age they have completed their moult and are referred to as a ‘beater’ because of the way in which they swim.
Lifespan: 25-35 years
Distribution: Harp seals are restricted to the north Atlantic where they are separated into three separate populations, each of which uses a specific pupping site. The Northwest Atlantic stock (Fig. 1), which is the largest, is located off eastern Canada. This population is further divided into two separate herds based on the breeding location. The Front herd breeds off the coast of Labrador and Newfoundland, and the Gulf herd breeds near the Magdalen Islands in the middle of the Gulf of St. Lawrence. A second stock, the Greenland Sea, pups off south east Greenland while the third stock (White Sea/Barents Sea) pups in the White Sea, in northern Russia.
Figure 1. Range, migratory pathways and whelping locations of harp seals in the northwest Atlantic
Population trends:
The harp seal population remains healthy and abundant. It is currently estimated at about 7.3 million animals, which is close to the highest levels observed since monitoring began in the 1950s (Fig. 2). There is some evidence to suggest that the Northwest Atlantic harp seal population may be reaching levels close to its natural carrying capacity, which is the maximum number of individuals of a particular species that can be sustained by that species’ ecosystem.
The slight decrease in the estimate of the current harp seal population in Canada is due to unfavourable ice conditions over the past few years, combined with new data indicating lower than average reproductive rates since 2008. Harp seals require stable ice for successful reproduction. Ice conditions in the Gulf and at the Front are currently at, or near, the poorest on record since 1969, the beginning of the measurement time-series.The Department is monitoring this situation closely, and any increased ice-related mortality this year will be taken into consideration when making future management decisions.
Figure 2. Estimated recent population trends of northwest Atlantic harp seals.
Conservation status in Canada: Harp seals are the only species of marine mammals in Canada not assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
Grey Seals
Photo Credit: D. Bowen
Size: Male grey seals may reach a length of 2.3 m in length and weigh as much as 350 kg. Females are smaller, reaching 2 m in length and weigh up to 227 kg.
Feeding habits and impact on the ecosystem: Grey seals feeds on a wide variety of fish including cod, flatfish, herring, skate, octopus and lobster. DFO has undertaken a number of studies on the relationship between grey seals and cod. As part of Science Advisory Process in October 2010, it concluded that predation by grey seals was the greatest contributor to increased mortality in large southern Gulf of St. Lawrence cod, but that grey seals were not limiting cod recovery off the eastern Scotian shelf. At the same meeting, it was concluded that, while grey seal predation on cod is important on the Scotian Shelf, it explained less than 25% of the cod mortality, whereas it could account for around 50% in large cod in the southern Gulf.
Reproduction and life cycle: Grey seal pups are born on land in late January to early February in the Western Atlantic. During their two week nursing period, pups double their weight reaching approximately 50 kg at weaning. Within their first month, they shed their white coat, grow dense waterproof adult fur, and soon leave for the sea to learn to fish for themselves.
Lifespan: 30 to 40 years
Distribution: Grey seals are found on both shores of the North Atlantic Ocean. In Canada they are found in the Gulf of St. Lawrence off the shores of Quebec, New Brunswick, Prince Edward Island, Nova Scotia and Newfoundland.
Population trends:
The Grey seal population has risen steadily over the last three decades. The total estimated grey seal population size at the end of the 2012 breeding season (including pups) was close to 350,000 (Fig.3). We estimate current reproductive rates at about 2% annually.
Figure 3. Estimated recent population trends of northwest Atlantic grey seals.
Conservation status in Canada: The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) designated grey seals ‘Not at Risk’ in April 1999.
Hooded Seals
Photo Credit: Mike Hammill
Size: Adult males average 2.6 metres in length and weigh between 300–460 kg. Females average 2.03 metres in length and weigh between 145–300 kg.
Feeding habits: The Hooded seal’s diet varies regionally and includes: Squid, Greenland halibut, redfish, cod, Atlantic argentine, amphipods, euphausiids, and capelin.
Reproduction and life cycle: Hooded seals give birth on pack ice during mid to late March. Pups are born with a slate blue-grey coat (blueback) which they moult at about 15 months of age. Females nurse their pup an average of only four days, during which the pup doubles in size.
Lifespan: 30 years.
Distribution: The hooded seal is only found in the central and western North Atlantic range from Svalbard in the east to the Gulf of St. Lawrence in the west. There are two distinct populations of hooded seals. The Greenland Sea population pups on the ice north of Iceland. The Northwest Atlantic population pups at the Front (off the coast of northern Newfoundland / southern Labrador), in the southern Gulf of St. Lawrence, and in the Davis Strait (between Greenland and northern Canada). After the breeding season, Northwest Atlantic hooded seals disperse to feed and migrate to the moulting areas off southeast Greenland. After moulting in July, they migrate along the Greenland coast to Baffin Bay and Davis Strait where they feed before returning to the breeding areas in late winter.
Population trends: Abundance of hooded seals is estimated from a population model that incorporates data on reproductive rates, removals and periodic pup productions. Historical trends in abundance of Northwest Atlantic hooded seals are poorly known, but it is believed that the population is at or above historical levels and is increasing. In Canada, theestimated total population in 2005 (last assessment) was 593,500. Greenland Sea hooded seals are estimated to have been reduced to less than 30% of their historical numbers with a current population size of approximately 85,800.
Conservation status in Canada: The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) designated hooded seals ‘Not at Risk’ in April 1986.
Ringed Seals
Photo Credit: Mike Hammill
Size: The smallest species in the seal family, Ringed seals average about 1.5min length and weigh between 50–70 kg.
Feeding habits: Ringed seals eat a wide variety of small prey including mysids, shrimp, Arctic cod, herring, smelt, whitefish, sculpins, perch, and other small fish or crustaceans.
Reproduction and life cycle: Females give birth to a single pup in March or April. Pups are born in a snow lair where they are protected from the environment and predators. They are weaned after one month.
Lifespan: 25 to 30 years.
Distribution: Ringed seals reside in Arctic waters and are commonly associated with ice floes and pack ice. The Ringed seal maintains a breathing hole in the ice allowing it to use ice habitat that other seals cannot. Ringed seals have a circumpolar distribution from approximately 35°N to the North Pole, occurring in all seas of the Arctic Ocean. In the North Pacific, they are found in the southern Bering Sea and range as far south as the Seas of Okhotsk and Japan.
Population trends: Little is known about the population of Ringed seals, however the North Atlantic Marine Mammal Commission (NAMMCO) estimates that approximately 1.2 million ringed seals would be needed to account for a proportion of the number of seals harvested and killed by polar bears in Baffin Bay.
Conservation status in Canada: The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) designated ringed seals ‘Not at Risk’ in April 1989. The COSEWIC Marine Mammal Subcommittee has recommended that there be a new assessment.
Harbour Seals
Photo Credit: Jean-François Gosselin
Size: adults can attain a length of 1.85 m and weigh about 110 kg
Feeding habits: Harbour seals feed upon a variety of fish and invertebrates as available, including sandlance, herring, pollock, cod, capelin and squid.
Reproduction and life cycle: Birthing of pups occurs annually on shore. The timing of the pupping season varies with location, occurring in February for populations in lower latitudes, and as late as July in the subarctic zone. Pups are capable of swimming and diving within hours and nurse for three to four weeks, doubling their weight by the time of weaning.
Lifespan: 30–35 years for females and 20–25 years for males.
Distribution: Harbour seals are found along temperate and Arctic marine coastlines of the Northern Hemisphere. They are found in coastal waters of the northern Atlantic and Pacific Oceans, as well as those of the Baltic and North Seas. In Canada, they may be found off the coastal waters of British Columbia, Nunavut, Manitoba, Ontario, Quebec, New Brunswick, Prince Edward Island, Nova Scotia, and Newfoundland and Labrador.
Population trends: The global harbour seal population is 5-6 million, but subspecies in certain habitats have been reduced or eliminated through outbreaks of disease (especially the phocine distemper virus) and conflict with humans. Populations of Harbour seals in British Columbia have been increasing since hunting ended in 1967. Abundance in Atlantic Canada is unknown but thought to have been reduced due to a hunt and bounty program that ended in the early 1970s. There are an estimated 20,000 to 30,000 Harbour seals in Atlantic Canada.
Conservation status in Canada: The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) designated harbour seals ‘Not at Risk’ in November 2007.
Bearded Seals
Photo Credit: Mike Hammill
Size: The Bearded seal reaches about 2.1 m to 2.7 m in length and weighs between 200 - 430 kg.
Feeding habits: The Bearded seal feeds on a variety of small prey found along the ocean floor, including crabs, clams, squid, and small amounts of fish. Its whiskers serve as feelers in the soft bottom sediments.
Reproduction and life cycle: In the Canadian Arctic, seal pups are born in May. Further south, in Alaska, most pups are born in late April. Pups are born on small drifting ice floes in shallow waters and enter the water only hours after they are born, and quickly become proficient divers. Mothers nurse for 18–24 days, during which time the pups grow at an average rate of 3.3 kg per day.
Lifespan: 25 years.
Distribution: Bearded seals are found in the Northern Hemisphere with a circumpolar distribution that does not extend farther north than 80°N. In Canada, Bearded seals are found throughout the Arctic and along the Labrador coast south to northern Newfoundland.
Population trends: unknown
Conservation status in Canada: The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) defines the status of bearded seals as ‘Data Deficient’.
