Pentland Firth - Marine Wildlife

Marine Wildlife

Seals can be seen at all times of the year in all parts of the firth. They usually bask on the rocks on the ebb (falling) tide since it saves them having to move as the water rises. Large groups of seals can be seen at the north of Stroma, from the lighthouse round to the north-west part of the island and at the south end in the area of the beacon and to the east between the old jetty and the lighthouse. On Swona they can be seen around the midpoint of the west coast. The Common Seal come in various colours with spots and have their pups in May, June and July. They are of a similar colour to the adults and can swim from birth, The Gray Seal, which is more common in this area having one of the largest British populations, also comes in a number of colours and live in colonies giving birth to white pups from October through to January. These pups do not swim at first until they shed their white coat. When giving birth seals can often be seen inland, sometimes quite a surprising distance.

Porpoises. Again can be seen all year round in all parts of the firth although they tend to favour shallower water. Grow to about 1.5m, black, with a broad based triangular fin which can be seen as they surface. It has a small, rotund body with a short, blunt head, no beak, and a small, triangular dorsal fin. Usually seen singly or in small numbers although in the autumn many groups may be seen in Gills Bay. When in groups tend to swim in a more random fashion than Dolphins who swim together.

Dolphins. Not very common but seen from time to time. Many different types visit the firth and may be seen anywhere at any time. Larger than Porpoises, 2-3m depending on the type, black, with the rear edge of the fin curved back at the top unlike the straight edge of the Porpoise. Head has a distinct beak. Often swim alongside the bow of vessels and frolic in the bow waves. Probably more than one usually swimming together in a more synchronised manner, sometimes leaping out of the water.

Killer whale. Mostly seen around May to July although may be sighted at any time of the year. Usually swim in a pod of a maximum of from six to twelve individuals led by a male up to 9m long who will be about 25% larger than the females and juveniles who make up the remainder of the pod. They tend to be fairly distinctive due to their size, fin and markings. The male has a very tall, triangular and erect dorsal fin which is sometimes tilted forwards. Juveniles and adult females both have a smaller, sickle-shaped dorsal fin. When surfacing the grey saddle shows up over the black back, behind the dorsal fin. It has a conical-shaped black head, with a distinctive white oval patch above and behind the eye, an indistinct beak, white throat and large paddle-shaped flippers.

Minke whale. Quite often seen in June and occasionally through to October but also at other times of the year. Tend to feed in the up-welling water of the tidal races but can be seen elsewhere. Usually seen singly but may be in pairs. Grows to 7-8.5m, black with diagonal white band on flipper and a slender, pointed triangular head. Relatively small dorsal fin curved back at top at rear part of body. Will probably see the long back with small fin to rear breaking the surface although they are known to bow and stern ride the waves of vessels.

Basking shark. Rare but being seen more often around May to August. A fish rather than a marine mammal spends most of its time cruising on the surface filter feeding. The dorsal fin can be seen moving steadily through the water with the tip of the tail moving from side to side behind it. Usually seen feeding inshore at high tide around here in the Gills Bay, Stroma area though may be seen in deeper water. Generally around 8m long, greyish brown to bluish black with pale belly. Seen in northern waters in the summer, southern in winter. Often in groups of three or four.

Turtles. Very rarely seen, however they are occasionally found caught in fishing nets in this area. The Leatherback is the most frequently recorded species in UK waters and probably the only one in this area. Grows to about 2.9m with an elongated black shell spotted with white, which tapers to a blunt spike. Migrates to UK waters from the tropics in the summer to feed on jellyfish. There are four other species less frequently encountered in UK waters where they usually occur as stray juveniles carried by currents from warmer seas.