My last blog post discussed the effects of climate change on polar bears. This post will focus on a specific type of Arctic seal that is being affected by climate change: the harp seal. There are a total of six types of seals in the Arctic region which include the harp, hooded, ringed, bearded, spotted, and ribbon. All six types are all being affected by loss of arctic sea ice in some way, but the harp seal is an example of a type of Arctic seal species whose lives are entirely dependent on Arctic sea ice, especially during birth. (National Snow and Ice Data Center, 2020).
Appearance and Location
Harp seals can be found around the Arctic Circle and North Atlantic Ocean. Their name comes from the black patch on their backs that looks similar to a harp. They can grow to be 260 to 300 pounds and 5 to 6 feet in length (NOAA Fisheries, 2022). Harp seals live at the edge of the sea ice all year round. Large groups will migrate south along the Newfoundland and Norwegian coasts to breed in the spring. Then, in late February or early March, thousands of female harp seals will gather to give birth on the sea ice (National Snow and Ice Data Center, 2020). They have their babies on Arctic ice floes which are large sheets of ice that float in the water.
Harp seal breeding is becoming greatly affected by climate change. Studies have predicted that warming Arctic waters and air will melt at least 20 percent of Arctic ice cover within the next 40 years (Smithsonian Ocean, 2013). When seal pups are first born, they spend most of their time on Arctic sea ice resting and nursing until they are big enough and ready to enter the ocean waters. Climate change has caused rapid melting of sea ice, causing seal pups to become forced into the ocean sooner than they would be ready to be on their own. Being in the ocean earlier than usual puts seal pups at risk for starvation, hypothermia, and getting crushed by moving Arctic ice. They also can become stranded or separated from their families and wash up on the shore as shown in the photograph below. The photo shows a young seal pup that has been washed up on the shore of Prince Edward Island. The future of these seal pups is often unknown.
Harp seals a little bit older than newborn seal pups called Yearlings, which are seals about one to two years in age are also being affected by climate change because they get their food from around the edge of the sea ice. The Harp Seal diet consists mainly of krill, and two types of fish: capelin and sand lance, which all consume algae on the edge of the sea ice and use the ice as shelter (Smithsonian Ocean, 2013). Since the melting of sea ice is affecting the food of the harp seal, it is also affecting them.
Harp seals migrate south after spending time on feeding grounds in the north. They move south to breeding grounds in the winter. These southern areas include the coast of Newfoundland, or even as far as the New England and mid-Atlantic coast. When harp seals migrate too far south, they often become washed up on many U.S. beaches. In 1991, around 3,000 sick or dead harp seals were found stranded on beaches in the northeastern United States (Smithsonian Ocean, 2013). Scientists from the Duke University Marine Lab have found that the loss of sea ice during the breeding season is directly related to the number of harp seals that end up stranded on North Atlantic coasts (Smithsonian Ocean, 2013).
There is a chance that harp seals could potentially adapt to the rapid decrease of Arctic sea ice. A great amount of genetic diversity within the harp seal species was found in the northeastern U.S.. A high genetic diversity can allow the species to adapt to threats such as diseases and the conditions of the environment. It is known that harp seals are able to tolerate a few years of unfavorable ice conditions, but not a long term rapid decrease of sea ice due to climate change (National Snow and Ice Data Center, 2020). This threatens the harp seal breeding season and leads to an increase in seal pup death. There is also the threat of human activities, such as hunting, on harp seals, but luckily, they are protected under the Marine Mammal Protection Act (MMPA). This was passed by Congress in 1972 to ensure that a variety of marine species are protected. Three federal organizations have the responsibility to make sure that this law is carried out. They include the U.S. Fish and Wildlife Service, NOAA Fisheries, and Marine Mammal Commission (NOAA Fisheries, 2022).
“National Snow and Ice Data Center.” Wildlife: Seals | National Snow and Ice Data Center, 3 Apr. 2020, https://nsidc.org/cryosphere/seaice/environment/mammals_seals.html#:~:text=Six%20seal%20species%20live%20in,sea%20ice%20edge%20all%20year.
Cammen , Kristina, and Brianne Soulen. “Ice-Loving Seals and the Loss of Sea Ice.” Ice-Loving Seals and the Loss of Sea Ice, Sept. 2013, https://ocean.si.edu/ocean-life/marine-mammals/ice-loving-seals-and-loss-sea-ice.
NOAA Fisheries. “Harp Seal.” NOAA, 20 Apr. 2022, https://www.fisheries.noaa.gov/species/harp-seal.