Grey seals (Halichoerus grypus – translated as hook-nosed sea pig) and harbour (also known as common) seals (Phoca vitulina) can commonly be found around the British coast during the year, yet without a little knowledge it can be quite tricky to identify which is which. Throw in a few other similar looking mammals we also get from time to time, such as bearded, harp, hooded and ringed seals that venture from the Arctic, and identifying greys is even more tough.

Around the UK’s coastal areas, grey seals enjoy a position at the top of the food chain, normally consuming a wide variety of fish and eels, but also known to take whatever else is local, including octopus and lobster.

The ecology consultancy team at SMRU estimate a population of around 120,000 living around in and around Britain, it’s estimated that fifty percent of the world’s population of grey seals live around the coasts of the UK, with numbers doubling since the 1960′s.

As is common in many mammals, seals suffer from a high rate of early deaths, with almost a third of all grey seal pups dying before they are a month old.

How to Tell the Difference

With a side-on view, grey seal’s noses are of a much flatter shape than those of harbour seals (who have a more distinctly shaped forehead). Also, grey seal’s eyes are placed further forward on their heads than harbour’s, about mid-way between their nose and the back of the head. Harbour seal’s eyes typically, are much closer to the front of their faces.

Grey seals also have double chins (unlike harbour seals).

In terms of physical size, harbour seals are the smaller of the two, with a typical adult harbour seal measuring in at between 130cm to 170cm in lenth. Even the smallest grey seals are bigger than this, with a typical adult being between 1.8m to 2.1m in length.

Coat markings

Another way to tell these seals apart is their coat patterns, with greys having a very clear contrast in colour between their pale tummy and dark grey back. Harbour seals have a more even covering of spots and blotches on their markings. It’s easy to get this wrong when they’re wet – as their appearance changes greatly between wet and dry coats – be aware and don’t be caught out.

PAMBuoy revolutionises marine mammal research and monitoring by providing high quality tool that sends acoustic data, in near real time.

PAMBuoy is built on the widely used software PAMGUARD, the leading solution for passive acoustic monitoring for the Oil & Gas industry.