Photo-Identification (photo-ID) is a non-invasive scientific method of recognising individual animals using natural markings on the body of an animal. Often, as with the Manx catalogues, this method uses the dorsal fin.

In other regions, scientists use different methods according to their target species. This may be the tail fluke of a humpback whale, or the patterns created by barnacles on a right whale. 

MWDW’s photo-ID is split into three photo catalogues for each species:

Well-marked catalogue

This contains individuals that can be recognised from a photo of either side of the dorsal fin due to having nicks on the trailing edge of the dorsal fin. Often, though not always, we have both a left and a right hand side image of each animal. 

Right hand side / left hand side catalogues

These are individuals that can only be recognised from photos of the right or left hand side of the fin. They have no visible nicks, but do have scars or lesions on the skin.

Photo-ID is an extremely powerful and important technique. It can allow us to analyse:

  • Re-sightings of individuals and return rate to Manx waters.
  • Social structures; who they share bonds with.
  • Where else they travel to within the British Isles or beyond.
Example of a well marked dolphin, number 053 in our catalogue
Number 053 can be recognised from either side of their dorsal fin due to the nicks on the trailing edge
This is R038 recognisable only by the right side of their fin due to the lack of nicks on the trailing edge
This is L08, recognisable on the left side only. L08 has a nice long scar and a series of smaller scars which make him identifiable
2018 dolphineers photographing a minke whale
Photo-ID licence

MWDW conducts photo-identification under a strict licence issued by the IOM Government Department of Environment, Food and Agriculture (DEFA).

The license states that any vessel on which a designated official of MWDW is onboard, may approach a cetacean or basking shark within close proximity for the sole purpose of collecting photo-identification data. 

Using public images

If you have been lucky enough to have been approached by a pod of dolphins or a basking shark, or indeed encountered some from land, the images may be good enough for photo-ID.

The majority of images we receive from mobile phones are good for social media use but excellent photo-ID shots are usually made using a DSLR camera. 

What makes a good photo-ID image?
  • Animal should be side-on 
  • Entire dorsal fin must be visible
  • Good lighting
  • High quality with no pixelation
  • No artefacts or splashes