You’ve got to feel sorry for sharks. Here they are, being a crucial part of the marine ecosystems, keeping the oceans full of diverse plant and animal life, and what do they get in return? Nearly wiped out.

Lately, though, people have been coming round to the idea that, maybe, sharks are just big ol’ softies that happen to be covered in teeth. At the very least, even if you don’t love the fishy predators, you probably wouldn’t want to, you know… slaughter a bunch of endangered species and feed them to your cat, right?

Well, bad news: a new study, published in the journal Frontiers in Marine Science, has found you might have unwittingly been doing exactly that. Using a technique called DNA barcoding, researchers sampled close to 150 different pet food products in Singapore and made an alarming discovery: nearly one-third contained shark meat, including from vulnerable and threatened species like the silky shark and whitetip reef shark.

“None of the products purchased listed shark as an ingredient, using only generic catch-all terms such as ‘fish’, ‘ocean fish’, ‘white bait’ or ‘white fish’ to describe their contents,” said study authors Ben Wainwright and Ian French.

“The majority of pet owners are likely lovers of nature, and we think most would be alarmed to discover that they could be unknowingly contributing to the overfishing of shark populations,” they added.

This is by no means the first time sharks have been found in places they shouldn’t be. A 2019 study from the US found that one in eight cosmetic products contained shark DNA. Squalene, or shark liver oil, is a frequent addition to moisturizers despite a plant-based alternative being readily available. Even worse, nearly two-thirds of pet food products sampled tested positive for shark DNA, most of which came from the endangered shortfin mako shark.

“Given the results of [this] previous study … we wanted to see if endangered sharks are also sold in Asian pet food,” the authors explained.

Overfishing, fueled by the growing shark fin and meat trade, is responsible for an estimated 100 million shark deaths annually, and many species are now all but extinct. What makes the situation worse is the relative lack of responsible fishing practices worldwide, adding even more pressure to the already-burdened sharks.

“We do not know whether the high incidence of sharks in pet food is an attempt to avoid the wastefulness of the shark fin trade where high-valued fins are retained and the low-valued carcasses are discarded; if this is the case, that may be commendable,” notes the study.

“However, we are skeptical that this is the sole reason that sharks end up in pet food.”

The study reveals that this use of sharks in pet food and cosmetics, without indication, is a global problem that we’re only really starting to understand. Because the additions are unlabeled, consumers can’t choose not to buy the offending products – meaning that companies really have no reason to stop.

“When viewed in the light of the facts that oceanic shark and ray populations have declined by 71% since 1970, and that three-quarters of all shark species are now considered at risk of global extinction, pet food is not a worthy use of these charismatic and ecologically important apex predators,” concluded the authors.

“Better labeling that avoids the currently used vague catch-all terminology would allow consumers to make more informed choices,” they added. “This in turn would benefit shark populations by helping to mitigate unsustainable fishing and resource use incompatible with their continued survival.”