Catalogue I.D. number: 017-03W_R (nickname: Smoothy)
The process is like a detective game in that you have a host of photographed individuals, your suspects, and you need to identify each of them. Each night the photos from the digital camera are downloaded onto the computer and the day’s encounters are divided up into separate files. Each land-watch shift and boat survey is considered a separate encounter and ‘spacers’ (for example a photo of a shoe) are taken to mark the end of an encounter. When on day-long, dedicated surveys each new group of dolphins is considered a new encounter.
Photos not useful for identification are then deleted from the folders. These include missed or late shots; photos at the wrong angle, ideal photos are taken at 90ยบ to the fin; photos taken against the light; shots that are too far away; and photos with too much water in the way of the fin. The remaining photos are then renamed with the date, encounter number, boat name (or land), photographers name and numbered consecutively.
The kept, good photos are then copied and a new folder created. Within this new folder all photos are cropped so that only the dorsal fin and part of the dolphin’s body are kept in the shot. If a photo contains more than one individual it is replicated and each dolphin cropped out. If the animals are too close together for successful cropping, paint is used to draw an arrow to the intended fin. Where a mother and calf have been photographed, the photo is duplicated and cropped to keep both individuals in the frame so that a database can be constructed of recent mothers and their calves. An arrow is used to identify the separate fins, see photo below. This stage can take a surprisingly long time especially when a large number of photos have been taken.
Unidentified I.D. number: U1(U2calf)_110414_001_seekat_PEV_058b_1
Next up is the matching stage. This is the most significant stage of the process whereby the suspects are identified and abundance estimates obtained. Firstly, internal matching is carried out. Using their uniquely marked dorsal fins, all pictures of the same individual within an encounter are given a temporary name (A, B, C, etc). This stage is relatively trouble-free as you become familiar with the shapes and nicks of each dolphin from that encounter. The suspects are then compared one-by-one to the I.D. catalogue in an attempt to find out who was at the scene.
This stage involves dedication and precision as each nick and scar needs to match in the way that jigsaw pieces need to match up to finish the puzzle. The detective needs to be aware at this stage that nicks and scars may change over time as scars fade and new nicks may be obtained. This is why it is important to regularly photograph individuals so that positive matching is achievable. Of course it is still possible that the dolphin in question can not be successfully matched to the catalogue as it may be a new individual; a juvenile who has not acquire any nicks yet; or the suspect does not have a well-marked dorsal fin.
Catalogue I.D. number: 066-10L_L
Any unidentified suspects that have certainly not been photographed before are added to the catalogue as well as up-to-date photos of individuals whose fins have changed. Once the photo-identification process is started, you can become quite devoted to the task and do not want to stop until all the suspects in question have been identified.
Youtube video:
Sea Watch Volunteers - Dolphin Photo Identification
http://www.youtube.com/watch?v=o_peF4r8eKk&feature=related
Sea Watch Foundation Team
www.seawatchfoundation.org.uk
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