Fauna of the Irish Sea

What is the most popular fish in the Irish Sea?

The most common fish species found in Irish Sea waters are: herring, cod, merlangus, plaice and small anchovies. The number and variety of fish increases as you move from the northern to the southern part. While herring, cod and haddock dominate in the northern areas, mackerel, merlangus and hake dominate in the southern waters. They form the basis of fishing in this region. Fishing for sea devil, eel and other rare but not prohibited species is also popular.

What types of aquatic organisms are found in the Irish Sea?

Seven community species predominate: brittle star, sea urchins, worms, mussels, tellina, scrobicularia plana and shell-towers. Scallops and king scallops are found in rocky areas. The silty seabed in deep waters is home to shrimp populations. 

What marine mammals live in the Irish Sea?

Whales, dolphins and harbour porpoises are often seen in the Irish Sea. Harbour porpoise, bottlenose dolphin and common dolphin are regular visitors to the region. The rarest species are the minke whale, fin whale, sei whale, humpback whale and the North Atlantic right whale, now thought to be almost extinct. In the eastern North Atlantic, sperm whales, northern bottlenose whales, long-finned pilot whales, killer whales, white-beaked dolphins, striped dolphins and Risso's dolphins. Harbour seals can also be considered indigenous. Harbour seals and grey seals live in the Irish Sea.

Zooplankton of the Irish Sea

Plankton includes bacteria and animals that float in the sea. Most are microscopic, but some, such as various species of jellyfish and Pleurobrachia bachei, can be much larger. The zooplankton is dominated by crustaceans, especially paddlefish. Many animals of the seabed, open sea and coast spend their juvenile stages as part of the zooplankton. The whole plankton world is vital as a food source for most species in the Irish Sea, including the largest. For example, the giant basking shark feeds exclusively on plankton, while the leatherback turtle's main food is jellyfish.

What invertebrates live in the Irish Sea?

The Irish Sea and its surroundings coastline are home to an enormous variety of invertebrate species, ranging from flower-like fan worms to predatory swimming crabs and the large chameleon-like cuttlefish. Some of the most important to other wildlife are reef-forming species such as the coastal capax horse mussel, intertidal honeycomb worm and subtidal honeycomb worm. They build up large structures over many years, creating surfaces, nooks and crannies where other marine animals and plants can spend part or all of their lives.

What reptiles live in the Irish Sea?

Leatherback sea turtles are regularly found alive or beached in and around the Irish Sea. This species moves north to the waters off the British Isles each year, following swarms of jellyfish as prey. 

What sharks can be found in the Irish Sea?

Irish waters are home to around 35 species of shark, including the blue shark, porbeagle, bluntnose sixgill, spiny dogfish and the world's second largest shark, the basking shark. These species are not dangerous to humans.

Jellyfish in the Irish Sea

Jellyfish are common in the summer and autumn months when the water is above +16C. A blue jellyfish with very dangerous tentacles has been found off the coast of Scotland in the Irish Sea. The average transverse diameter of this jellyfish is 15 centimetres. The colour varies from dark blue to light blue.

Shark, Porbeagle

Shark, Porbeagle

Latin name Lamna nasus Other names Beaumaris shark, blue dog, bonito shark, herring shark, macker..



Shrimp (Caridea) - suborder Decapoda. The abdomen is muscular, longer than the thorax. Many have cla..

Striped dolphin

Striped dolphin

Latin nameStenella coeruleoalbaOther namesEuphrosyne dolphinIdentificationIt is distinguished from o..

White-beaked dolphin

White-beaked dolphin

Latin nameLagenorhynchus albirostrisOther namesLagenorhynchus albirostrisIdentificationThey have a r..

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