New research studying the behavior of Port Jackson sharks has captured their shrewd ability to realize when the scent of natural prey does not lead to a feeding opportunity.
The study by shark ecologists from Flinders University and Macquarie University found that sharks’ response to the smell of food decreased if they were not sufficiently rewarded with the promise to eat, suggesting that they can learn to avoid wasting time and energy on inaccessible food sources.
The researchers say the results, published in animal behaviorare a catalyst for better understanding the evolutionary learning capacity of sharks and their response to tourism that uses food or smell to lure sharks close to visitors.
The researchers used three groups of captive Port Jackson sharks to study their response to odor at different reward frequencies – the first group was rewarded with food each time they hit a target, the second were not rewarded than every other day and the third group was never rewarded.
The group of sharks that were always rewarded quickly learned the task and became better and faster at hitting the target.
However, the reverse was true for the unrewarded sharks, where they observed a reduction in their natural response to smell and potential food stimulus, with the sharks no longer moving from their starting position.
“Our study found that although shark behavior may change when frequently rewarded with food, the learned response decreases when reward frequency decreases and disappears even when no reward is provided,” says Dennis. Heinrich, lead author and recently completed PhD student at Flinders University.
“The observed decline in response to repeated stimulus, or habituation, may act as a driver of optimal foraging strategies, allowing sharks to rapidly abandon low-yielding foraging areas in search of sites more productive.”
Lead author and marine ecologist Professor Charlie Huveneers of Flinders University says there is still a lot we don’t know about shark behavior.
‘One of the questions I get asked the most is what can sharks learn and how does this relate to wildlife tourism which uses food or scent to attract sharks,’ says Professor Huveneers .
“From a wildlife tourism perspective, our results show that learned behavior can be reduced by decreasing feeding frequency, but that using only olfactory cues (i.e. smell) n is not always sufficient.
“The insights gained from this study can help take learned behaviors and habituation into account when managing wildlife tourism in the future. A balance must be struck between attracting sharks for tourism purposes and minimizing behavioral response and possible learned behaviors.
The researchers say the next step is to test their findings with species that are more commonly targeted by wildlife tourism, such as white sharks, and determine if habituation can be detected at tourist sites.
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