The seas of Arran
molluscs and crustaceans. Whilst venturing around the coast, always remember to look out to sea as you may see a cetacean - whale, dolphin or porpoise. The smallest species – the harbour porpoise – are year-round residents in Arran’s waters and commonly seen from the ferry. Growing to between 1.3m and 1.8m long, they are easy to miss, as only their rounded backs and small dorsal fin briefly break the water’s surface as they travel around in small pods.
If you witness a more flamboyant spectacle, you are likely watching bottlenose dolphins, which enjoy leaping and breaching clear of the water, or playing the waves created by boats. These charismatic creatures grow up to 3.5m long and have a much larger, more pointed dorsal fin than their smaller cousins.
Other cetaceans you could be lucky enough to spot are minke whale, orca, risso’s dolphin and common dolphin, all very rare but they have been recorded around the Clyde.
Otters, too, can be readily seen around Arran on any walk around the coast, although they are not always easy to spot. While not a fully marine species – they need ready access to freshwater – otter feed in the shallow waters around the coast, eating crabs and small fish.
Historically the abundance of marine mammals and sharks recorded in the Clyde region were much greater, so much so it is hard for us to appreciate just how numerous they might once have been.
Our seas were once bubbling with marine mammal activity, as described by fisherman P
Wilson in 1887 ‘at least 40 whales in pairs and hundreds of porpoise feeding’ just alongside his boat. It is therefore important to remember the numbers we see now are a fraction of much larger populations that once existed and that action to properly protect and recover these species is still urgently needed.
As top predators, these charismatic animals are vulnerable to any impacts on the marine food web, such as changes in plankton distribution as a result of warming seas and over-fishing of various prey species. All cetacean species, basking sharks, seals and otters are to some degree protected in law, but they are still vulnerable to many other impacts. They continue to be affected by persistent chemicals that can accumulate in their body tissues; they become entangled in marine debris including litter, aquaculture and fishing gear; irresponsible tourism disrupts important breeding, feeding and rest periods, and they can be disturbed by boat traffic and underwater noise.
The protection of seabed habitats and marine life within the Lamlash Bay No Take Zone (NTZ) and South Arran MPA clearly has direct benefits for otters, seals and some of the smaller elasmobranch species, but for wide-ranging transient species such as basking shark and cetaceans, the NTZ and MPA can only provide a limited amount of direct protection.
To ensure the conservation of these charismatic animals we are so fortunate to see around Arran, effective spatial management must be implemented more widely in Scottish seas.