I was wondering whether anybody has come across AI-software that would be able to re-identify animals - I am looking for a tool to re-identify giant tortoises.

I have a small group of around 150 tortoises that have all being photographed from above during an annual census (see example below. Note that the yellow marking will have worn off after a year). I am wondering whether there is already a tool that could help me re-identify the same animals when photographed a year later. Most approaches I have come across so far require a large amount of training photos. However, I only have one, maximum two photos of each animal that would be available for training. Tortoises' shell patterns are quite different between individuals, so I was wondering whether that may be enough. 

Please don't hesitate to reach out, even if you have just come across a tool that is in the making (i.e. developing project) or if you are unsure whether your suggestion is suitable.