Overfishing is a serious threat to the world’s oceans that continues to significantly impact the marine ecosystem. Now, a new study shows that one in seven species of deepwater sharks and rays are threatened with extinction due to overfishing.

The study, led by researchers from Simon Fraser University, examined more than 500 species of sharks and rays and involved more than 300 experts from around the world. The findings showed that around 60 species are threatened with an increased risk of extinction due to overfishing, according to the criteria of the International Union for Conservation of Nature (IUCN) Red List of Threatened Species.

According to the researchers, sharks and rays are caught as incidental bycatch in fisheries that usually focus on more commercially valuable species. However, they are kept because they are valuable in the oil and meat market. In recent years, there has also been an increase in the trade of shark liver oil, which has further reduced their population, the university’s press statement explained. The findings were published in the journal Science.

“About half of the world’s sharks are found below 200 meters, below where the sunlight reaches into the ocean,” study author Nicholas Dulvy said in the statement. “As the high seas and the coastal waters are becoming depleted in many countries of the world, we’re incentivising fishers to fish offshore and it’s become technologically viable to fish up to a kilometre deep,” Dulvy added.

Deepwater sharks and rays have long lifespans and low reproductive rates. Their life cycles are more similar to marine mammals such as whales and the walrus. According to the researchers, they can only withstand significantly small amounts of fishing pressure. Some of the species can take 30 years or more to mature, and even up to 150 years in the case of the Greenland Shark, and only produce 12 pups throughout their entire life, the statement elaborated.

Previous studies have also warned about the negative impact of overfishing on the marine ecosystem. For instance, a 2023 study published in the journal Science revealed that reef sharks, found in coral reefs, are disappearing due to overfishing, with the five most common species experiencing a decline of up to 73%.

The new study’s researchers suggest the protection of 30% of the world’s oceans by 2030, which would provide 80% of species partial protection across their range. They also mentioned that there should be a worldwide prohibition on fishing below 800 meters to provide 30% vertical refuge for a third of threatened deepwater sharks and rays.