Mourne’s inshore waters support a wide diversity of marine biodiversity and habitats fed by a plankton rich sea. 

• Cormorants, seals and harbour porpoise are often seen off shore and basking sharks are rare summer visitors.
• Deep-water muds contain burrowing prawns and crustaceans, with rare sea pens in Carlingford Lough.
• The shallow waters of Dundrum Bay are a vital fish nursery and important wintering area for sea birds including common scoter.
• Sandwich terns nest on Carlingford Lough’s islands and feed along the coast, especially in Dundrum Bay, along with gannets and Manx shearwaters. 
• Boulder beaches are clothed in barnacles or seaweeds, which shelter whelks, crabs, sea anemones and small fish.
• Mudflats in Mill Bay, Carlingford Lough, and Dundrum Inner Bay provide wintering  ducks and waders with buried worms and shellfish, while light-bellied Brent geese feed on eelgrass and neighbouring fields. 
• A wide variety of shells are washed onto the tide line on sandy beaches.

Common (or harbour) seals are seen off the Mourne coast basking on rocks or ‘bottling’ nose-up in the water. They breed on islands in Carlingford Lough, and on sand flats in Dundrum Bay. They are sometimes joined by the larger grey seal, which has a longer face. Being fish eaters, seals often come into conflict with fishermen but, as an important part of Europe’s seal population, they are protected. Please avoid disturbing them.

Characteristic of shores where there are rocks or boulders on which to attach and wave action is not too severe. Channel wrack lives in the highest splash zone, with various bladder wracks growing in bands down to the lowest tide line (low water). Below low water, tall kelp forests protect delicate red seaweeds and marine animals amongst their stems and thus are important fish nurseries. Wrack specifically grown on stones laid out in Mill Bay and piles of weed left in winter storms were once both commonly used as fertiliser on the land of the Mourne Plain.

Biodiversity Biodiversity Map Some of the most accessible areas designated for the quality of their biodiversity include:
  1. Carlingford Lough - Ramsar, SPA, ASSI
  2. Castlewellan Lake - ASSI
  3. Eastern Mournes - SAC, ASSI
  4. Murlough dunes - SAC, ASSI, NNR
  5. Rostrevor Wood - SAC, ASSI, NNR
  6. Slieve Croob - SLNCI
Explore other habitats