Marine Megafauna

Minke Whale © Eleanor StoneMinke Whale © Eleanor Stone

Situated in the middle of the Irish Sea, the Isle of Man is surrounded by a wealth of marine mammals, from basking sharks to dolphins, and seals.

One of the great pleasures about the Island is the accessibility and opportunity to watch marine life of all sorts.

Basking sharks

Basking shark. FHABasking sharks are the second largest fish in the world and the Isle of Man is a global hotspot for them.

Although they can grow to over 10 metres long and weigh as much as 7 tonnes, they are gentle giants, feeding only on tiny animal plankton which they sieve out of the water by swimming through it with their vast mouths wide open.

During May to August, basking sharks visit our shores and these magnificent animals can often be seen from the shore on the west coast, at places like Peel Castle, Niarbyl, Bradda Head, Port Erin.

Whales, dolphins and porpoises

Cetaceans, the collective term for porpoise, whales and dolphins, can often be seen off the island's coast.

Minke whale. Eleanor StoneThey are superbly adapted for life at sea and are powerful swimmers, some species are incredibly acrobatic and playful, capable of leaping out of the water, often for what seems like the sheer joy of it.

Although several species have been recorded in the Irish sea, the most commonly seen cetaceans around the Isle of Man are the harbour porpoise, Risso’s dolphin, minke whale, bottlenose dolphin and common dolphin.


There are two species of seal found around the Isle of Man – the Atlantic Grey seal, and its slightly smaller cousin, the Common Seal.

Contrary to its name, the Common seal is much scarcer around the Island than the Grey – on average there is about 10 grey seals for every Common seal.

Grey seals. Eleanor StoneIts not always easy to tell the two species apart – both can be a range of colours from black through brown, grey or tan, with patches of various shades and hues. The Common seal however has a more distinctive dog-like rounded head, while the Atlantic has a longer, more ‘Romanesque’ snout !

Both species breed in Manx waters, but their breeding habits differ somewhat from each other. The Common seals undertake their courting and mating ritual mostly underwater, and the females give birth to their young pups in the early autumn. These pups are born in an advanced state of development and can swim within a hours of their birth.

By contrast, the Atlantic Grey seals are more gregarious in their nature, with the females coming ashore in the early autumn to favoured breeding sites, called a ‘rookery’, such as in the Sound, where they give birth to their pups with their distinctive while furry coats.


Small Shark Tagging

For more information on our work tagging our small sharks, working with DEFA and local anglers, see our page and find out how you can get involved to help us understand more about these key species in our marine ecosystems .