Finally each catalogued dorsal fin photo is assigned one of four survey area tags (Area One -Big Marco pass; Area Two – Open Gulf; Area Three – Naples; Area four – Goodland) based on where they have been sighted.
When trying to determine the identity of a dolphin that appears in one of the sighting photos, the goal is to reduce the possible catalogue matches from over 500 to 1.
The first Step is to screen for dolphins from the survey area(s) where the photo was taken.
Next the search is narrowed to those fin categories that match the unidentified dolphin’s.
Finally those options are further narrowed by screening for the severity of the feature.
If this does not produce a match the procedure is repeated after removing the area filter. At this point if a match has been found the identified dolphin’s name is added to the sighting form. If not the new dolphin is given a name and his profile added to the catalogue. Then it is added to the sighting sheet.
Some photo-identification studies assign a quality grade to each photo based on things like focus and orientation of the dorsal then only include the highest quality photos in their analysis. We have not taken this step. In part, familiarity with many of the dolphins in Area One after years of observation allows us more confidence in identifying individuals using less than optimal photos.
The photos that were used to identify individuals are, however, uploaded with each siting and available to be checked for accuracy.
There are occasions where both observers on the survey team sighted a familiar dolphin during a sighting but, for whatever reason, were not able to capture an image of the dolphin. Those dolphins were included in the sighting report with a note acknowledging a visual sighting without available photo.
1. Wells, Randall. “Social Structure and LIfe History of Bottlenose Dolphins Near Sarasota Bay, Florida: Insights from Four Decades and Five Generations.” Primates and Cetaceans: Field Research and Conservation of Complex Mammalian Societies, edited by J.Yamagiwa and L. Karczmarski Springer Japan, 2014, p. 156