Personality in animals is actually similar to personality in humans. Essentially we look for differences in behaviour between individuals of the same species, in this case the lemon shark. In a non-technical, human context, anyone is capable of basically assessing such differences. For example, you might describe one person as more social than another or someone else as calmer, and so on. We compare people instinctively and are thus able to classify their personalities in a non-systematic way.
A comparative psychologist or animal behaviourist, however, needs more to be able to specify animal personality. It is not enough that individual subjects simply show differences in behaviour; they must do so consistently. For instance, you meet two people at a party: one may be social and the other less so. If you meet them again you would expect them to show the same differences: the social person would remain social and the less social person would still be less social. In a similar way this is what we are looking for in sharks. If the shark displays the same behaviour over time, it demonstrates that it has personality.
Studying personality in humans is comparatively straightforward. You can ask them to fill in a questionnaire, for instance. However, it is fairly difficult for a shark to complete a questionnaire! So to demonstrate and classify the personality of individual sharks, some sort of behavioural test needs to be designed. Observations have to be based on natural behaviour of significance to the juvenile lemon sharks. The trick is knowing what is important to the shark, and happily – due to decades of study at the Bimini Biological Field Station, or Shark Lab – we know a lot about the behaviour of juvenile lemon sharks. And this has been very useful in my own first investigation of personality in lemon sharks.
Samuel, better known as Doc, has been studying sharks for 50 years. He discovered how sharks see and even gave us insights into how they think. He founded the Bimini Biological Field Station in 1990, and has been training and inspiring young shark researchers ever since.