Mammals
The rich marine life of sea lochs provides ample feeding for mammals particularly otters, seals, harbour porpoises and some other cetaceans.
Otters are equally at home in freshwater, brackish or fully marine habitats and the sheltered waters of many sea lochs are ideal for them. They are particularly attracted to rocky shores and shallow water with an extensive seaweed cover where they may be seen hunting their main food, fish and crabs. Otters prefer areas little disturbed by humans with suitable sites for their dens or holts, although they can sometimes be seen on busy slipways. Although protected by legislation, otters have declined in many parts of Britain and Europe but appear still to thriving in western Scotland. However, as a slow breeding, low density species they are vulnerable to any factors which might cause sudden population changes.
At first glance the North American mink might be mistaken for a small otter. Originally bred for their fur, escapees from mink farms now live wild in various parts of Scotland occupying similar territory along waterways and sea loch shores to otters. Mink are ferocious predators of other small mammals and birds – ground nesting birds are particularly vulnerable to mink predation, as well as fish.
Both common and grey seals live on the west coast of Scotland, but common seals are more likely to be seen inside sea lochs, particularly near the entrance and on offshore islands and skerries. Common seals are the smaller of the two species and are best distinguished by their slightly up-turned nose, like a Labrador dog in profile, compared to grey seals which have a longer straight profile or rather ‘Roman nose’ in the larger males. Seals are attracted to fishfarms, both by the wild fish which congregate around them to eat any surplus fishfood and by the captive salmon. Seals will attack salmon through the mesh of fish cages and anti-predators nets have to be used on the outside of the cages to deter them.
Although cetaceans (dolphins, porpoises and whales) are more often seen in open water, harbour porpoises are frequent visitors to sea lochs and several species of dolphin also visit regularly. These small cetaceans are accustomed to inshore navigation. Minke, killer and other whales occasionally enter sea lochs but it is thought that these larger animals may have strayed into sea lochs by accident or are themselves sick or accompanying another sick animal.