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Sharks learn to stop wasting time on prey they can't catch

A new study led by Flinders University and Macquarie University in Australia has found that sharks’ response to the smell of food declined if not sufficiently rewarded by the promise of eating. These findings suggest that sharks can learn to avoid wasting time and energy on food sources that are inaccessible. Since wildlife tourism often uses food or smell to attract sharks to the proximity of visitors, understanding sharks’ habituation to food-related olfactory cues is necessary to help this type of tourism run smoothly.

The scientists used three groups of captive Port Jackson sharks to study their response to smell across different reward frequencies. While the first group was rewarded with food each time they reached a target and the second one was rewarded every other day, the third one was never rewarded. 

The sharks that were always rewarded learned quickly the task and became faster and better at reaching the target. In the case of the un-rewarded sharks though, the scientists observed a reduction of their natural response to the smell of potential food, with some sharks not even leaving their starting position after a few trials.

“Our study revealed that while shark behavior can change when frequently rewarded with food, the learnt response diminishes when reward frequency is decreased and even disappears when no reward is provided,” said study lead author Dennis Heinrich, a recent PhD graduate from Flinders University.

“The observed decline in response to a repeated stimulus, or habituation, may act as a driver of optimal foraging strategies, enabling sharks to quickly abandon low-yielding foraging patches in search of more productive sites.”

In future research, the scientists want to test these findings with species that are more commonly targeted by wildlife tourism, such as white sharks, and investigate whether habituation can be detected at tourist locations.

“The knowledge gained from this study can help account for learnt behaviors and habituation when managing wildlife tourism moving forward,” said study senior author Charlie Huvenaars, a marine biologist at Flinders University. “A balance needs to be found between attracting sharks for tourism purposes and minimizing behavioral response and possible learnt behaviors.”

The study is published in the journal Animal Behavior.  

By Andrei Ionescu, Staff Writer

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