Researchers have found individual personalities in the Port Jackson sharks through a personality test study among several animals from the same species. The team was from Macquarie University in Sidney, Australia and was the first one to prove the animals have personalities just like humans do.
The team from the Department of Biological Sciences analyzed the different reactions of the animals to pre-established situations in which they were put on. The animals had distinct and consistent or correlated responses when exposed to an unfamiliar environment and stress, according to the study published in Journal of Fish Biology.
“Over the past few decades, personality research has shown that nearly 200 species of animals demonstrate individual personality,” said lead author Evan Byrnes. “Personality is no longer considered a strictly human characteristic, rather it is a characteristic deeply engrained in our evolutionary past.”
For the study, researchers performed trials designed to test the shark’s boldness, which measured their propensity to take risks but in addition an influence on individual health through its correlation with stress hormones and associated physiological profiles, according to a press release about the findings made by the university.
First, the sharks were introduced to an unfamiliar shelter while researchers timed how long they take to go outside the refuge box and explore the new environment. The second behavior test consisted in putting the animals outside the water and analyzed how each one reacted to the stressful situation and observed how quickly they recovered from it after they were once again in the water.
It was found that each behavior was consistent over the repeated trials, which indicated ingrained behaviors instead of chance reactions. Some animals were consistently bolder than others in the different scenarios, and the sharks that were the most reactive to handling stress in the first trial were also the most reactive in a second trial.
The team concluded the paper by saying the results demonstrated the presence of individual personality differences in sharks for the first time in history. Understanding how personality influences variation in elasmobranch behavior such as prey choice, habitat use, and activity levels are critical to better managing these top predators, which play an important ecological role in the marine ecosystem, the team said in the published paper.
“Not mindless machines”
According to Associate Professor Culum Brown, the team is excited about the results because they demonstrated that sharks are not just mindless machines. Just like humans, each shark is an individual animal with its unique preference and behaviors, he said.
The results rose a number of questions about individual variation in the behavior of top predators and the ecological and management implications this may have, Brown commented. If each shark is an individual and doing its own thing in its own environment, then clearly managing shark populations is much more complicated than was previously thought, he added.
Source: Macquarie University