In 2014, researchers from the University of Exeter in the U.K. watched groups of catsharks interact in three different habitats. Even though the sizes of the groups changed, the scientists noticed that the same "well-connected" sharks stayed in their social cliques and less-social sharks hid by themselves regardless of the habitat.
In 2016, a study was published in the Journal of Fish Biology that looked at other shark personality traits in two tests. For the first test, the researchers put Port Jackson sharks in a cramped underwater enclosure and timed how long it took each shark to peek out at its surroundings, then finally swim into the open. For the second test researchers stressed each shark by holding it out of the water for 60 seconds, then determined its anxiety level by recording how many times per minute it beat its tail once it got back in the water. In both tests, sharks behaved in many different ways. Some showed boldness by emerging from the box in a matter of seconds while others were hesitant for up to 20 minutes, and their tendencies toward anxiety also ran the gamut.