Stenella coeruleoalba (Striped Dolphin)  

In the North Atlantic, striped dolphins are typically found in water depths of 1,000 metres or more beyond the continental slope, but the species has been recorded in shallower waters around the Scottish mainland and west of the Faroe Islands. Striped dolphins off the west coast of Scotland are rare and the records for the Outer Hebrides are mainly of stranded animals.

Additional Information
Hebridean Whale and Dolphin Trust
Cetacean Research & Rescue Unit