Researchers sound alarm after witnessing troubling shift in shark behavior near tourist hotspots: 'They were essentially eating junk food'

Reef sharks in French Polynesia are suffering from being fed by tourists.

What's happening?

A study published in Animal Conservation revealed blacktip reef sharks in Mo'orea are feasting on low-quality scraps that are harming their metabolic and reproductive health, Science News reported.

Marine behavioral ecologist Johann Mourier of the Center for Insular Research and Environmental Observatory led the research, which took place from 2008 to 2011 and involved 117 sharks at 17 locations.

"The volume of blood made up of red blood cells — an overall measure of health condition — was lower for both sexes at the feeding sites," Science News stated. Female sharks during breeding season at these hotspots had less glucose in their blood, indicating they were essentially eating junk food. Males had higher levels of testosterone, perhaps because of increased competition for the treats, which are used to attract marine life.

All the females that lived away from the feeding sites were pregnant, and they had three times the amount of one kind of estrogen. Female sharks at the feeding sites were not all pregnant.

Why is this important?

This is affecting reef sharks because they stick to small areas, while other species cover larger ranges, according to Science News. Bahamian nurse sharks could be similarly impacted.

The species is at risk because of overfishing and habitat destruction, per Oceana. Globally, reef sharks are being stressed by rising ocean temperatures and the resulting loss of coral.

The paper highlighted that viewing wildlife by feeding it is a popular form of ecotourism. It noted that studies on the consequences of this behavior are lacking but that the health impacts on the animals "are becoming increasingly evident."

"An unpredictable, low-quality diet at feeding sites may be making it harder for female sharks to invest in the next generation of pups," Science News stated. "Further research could determine how feeding impacts reproduction and fitness in the long term and across multiple generations."

What's being done about feeding the blacktip reef sharks?

The researchers said that feeding regulations should be instituted or improved and that foods should be chosen based on nutritional content, especially during breeding season.

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"[Shark tourism] is very beneficial for the sharks' conservation, for us to educate people around that," Mourier said. "But you also need to better manage the activity."

To help, donate to conservation organizations and efforts that protect endangered species and travel to destinations with environmentally responsible tourism businesses.

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