The Harbour seal (Phoc vitulina) is one of the two species of seal found around the coast of Iceland that reproduce on the shores. An adult seal is brown, silvery white, tan, or gray with V-shaped nostrils. They are on average 1.85 m and 168 kg. They possess a unique pattern of spots, and their body and flippers are short. They can live between 25 to 30 years old.
There are estimated 350,000-500,000 harbour seals worldwide. They have the widest distribution of any seal and are found from the North Atlantic to the Northern Pacific Ocean. They are found on coastlines in temperatures varying from temperate to arctic. In Iceland, the population has declined from 33,000 in 1980 to less than 7,000 in 2016.
The harbour seal spends most of its time alerting predators including polar bears, orcas and sharks. They use vocalizations to maintain a social hierarchy and to ward off danger. Although they are primarily solitary, they congregate in somewhat antagonistic groups during the breeding season. They will bite, head butt, snort, growl, and wave to keep other individuals away from them. They are a polygamous species; the males mate with multiple females in one season. Both the courtship and the mating undergo underwater.
They spend half their time at sea and the other half in the ocean. They can dive up to 152 metres and can remain submerged for up to 30 minutes at a time. They do this by slowing their heart rate for about 80 beats per minute to as little as 3 or 4. They are able to do this dive by using stored oxygen in their muscles and blood instead of their lungs.
Their diet primarily consists of fish, cephalopods and crustaceans. They may spend several days at sea and travel up to 50 km. They will hunt in harbours, bays, sandy intertidal zones, and estuaries to pursue multiple different species of fish.
Despite only being of Least Concern on the IUCN, the Harbour seal is now endangered in Iceland due to a 77% drop in population in 35 years. The primary reason for this decline is due to pollution, changing ocean conditions, diseases and hunting. The species has been named critically endangered in Icelandic waters by the Icelandic Institute of Natural History.
Entanglement: Harbour seals become entangled in fishing gear and other marine debris. They can be completely entangled that can result in death.
Illegal Feeding and Harassment: Human disturbance from vessel traffic and disturbance can displace seals from their resting spaces.
Habitat Degradation: Physical barriers include on and offshore development and boat traffic that prevent the seals from reaching their breeding, migration, feeding or pupping areas.
Chemical Contaminants: Contaminants from gas and oil development, urban runoff, and other industrial processes cause bioaccumulation up the food chain that can threaten immune and reproductive systems.