You know how the old saying goes — one man's trash is another deep-sea shark's treasure.

Wait ... what?

Joan Cartes of the Institute of Marine Sciences in Barcelona — as reported by the New Scientist — has learned that deep-sea sharks and other bony fish in the western Mediterranean Sea are feeding on humans' discarded food at a frenzied pace.

The leftovers that they are devouring between Barcelona and the Balearic Islands, include everything from beef to goat meat, vegetables and fruit.

Researchers were able to study the sharks and bony fish's consumption by catching 445 live fish — including three different species of sharks and six different kinds of bony fish — and analyzing the contents of their stomachs.

The point of the study is to discover just how much human leftovers and debris discarded in the water are affecting the food webs of deep-sea sharks and fish.

"Plastics were frequently found, but in small volumes of the total diet, typically less than two percent by weight," Cartes told the New Scientist.

Although the amount of human-discarded food that fish feed on is alarming, it pales in comparison to that consumed of other dead fish and animals — which New Scientist reports is as high as 70 percent of sea sharks and bony fish's stomach contents.

Cartes believes these findings could be happening in other bodies of large water around the world, too.

"I think all deep-sea systems in the world may be exposed to similar impacts," Cartes said.

David Bailey, from the University of Glasgow in the United Kingdom, additionally told New Scientist:

"Humans have probably had all kinds of effects on food availability to deep-sea scavengers through fisheries discards, changes in fish stocks and whaling. In the enclosed Mediterranean, the effects of food from the land are likely much stronger than out in oceans. So while I'm not surprised by these findings, they're interesting and show how much we're affecting deep-sea systems, even though they're out of sight."