With the increasing number of humpback whale sightings near the islands surrounding Reykjavík, we're delighted to observe seals regularly during our tours! It's the perfect opportunity to shine a light on the fascinating ecology of the harbor and grey seals, and to share some insights on how to distinguish between these two species.
Harbour seal. Photo by Megan Whittaker.
Grey seals are notably larger, typically measuring around 2,5 meters in length and weighing between 200 to 400 kilograms. In contrast, harbor seals reach up to 2 meters and weigh around 100 kg. Grey seals have a more oval shaped head with a long nose, and the eyes are more towards the side of the head. The head of a harbour seal is more rounded, the big eyes pointed to the front, and their nostrils creating a heart-shape.
Grey seal on the left, harbour seal on the right. Photos by Rob Hyman.
In Icelandic, the grey seal is known as ‘útselur’ (out-seal), suggesting their tendency for oceanic adventures, while the harbour seal is called ‘landselur’ (land-seal), hinting at their preference for staying closer to shorelines. Grey seals are fast swimmers, reaching speeds up to 35 km per hour (though they typically swim around 10 km per hour), outpacing the harbor seals, which have a maximum speed of 19 km per hour. Both species are skilled divers, capable of holding their breath for over thirty minutes and diving several hundred meters deep.
Grey seals. Photo by Rob Hyman.
Seals have good eyesight and can use their vision, along with their sensitive whiskers, to locate prey in murky Icelandic waters. Grey seals like to eat cod, sand eels, saithes, and lumpsuckers, and harbour seals often go for small cod, redfish, baitfish, flatfish, and herring.
When it comes to family time, harbour seals have their pups in early summer, while grey seals wait until later in the year. Many seal species can delay pregnancy with an incredible trick called embryonic diapause, where they delay the implantation of an embryo to ensure their pups are born at the best time for food availability.
Sadly, both species have experienced steep population declines in Iceland. From 1980 to 2000, the harbor seal population dwindled to a third of its previous size, and the number of grey seals has also decreased by thousands since the 1990s. Threats such as habitat degradation and entanglement in fishing gear pose serious risks to these beautiful creatures.
A young harbour seal. Photo by Whale Safari.
We feel very lucky to find both seal species lounging around their favorite spots near Viðey island, adding some fun bonus sightings to our whale watching experiences. It is yet another reminder of the incredible wildlife we have here in Reykjavík.
By Eline van Aalderink