Scientists have found some very bad news when it comes to the massive creatures that roam our planet — a new survey of extinction patterns indicates that the largest species in the ocean are the most likely to face extinction thanks to the activities of humans.

The larger an animal it is, the more at risk it is, scientists from the Stanford University found, according to a statement. This is because that people tend to target larger species for consumption.

The researchers made this determination by examining the relationship betwen risk of extinction and body size over the last 500 eyars for mollusks and invertebrates, and then comparing modern extinction patterns to ancient ones. They examined the fossil record dating back 445 million years, although the last 66 million years — since the last mass extinction event — received the bulk of their focus.

They found that over the last 500 years, body mass had corresponded with the threat of extinction big time. It raises concerns that we may be seeing megafauna on our Earth dwindle toward extinction, much like the mammoth and saber-toothed tiger many years ago.

“We see this over and over again,” study co-author Noel Heim, a postdoctoral researcher, said in the statement. “Humans enter into a new ecosystem, and the largest animals are killed off first. Marine systems have been spared up to now, because until relatively recently, humans were restricted to coastal areas and didn’t have the technology to fish in the deep ocean on an industrial scale.”

Added Jonathan Payne, a paleobiologist at Stanford’s School of Earth, Energy & Environmental Sciences: “We can’t do much to quickly reverse the trends of ocean warming or ocean acidification, which are both real threats that must be addressed. But we can change treaties related to how we hunt and fish. Fish populations also have the potential to recover much more quickly than climate or ocean chemistry,” Payne said. “We can turn this situation around relatively quickly with appropriate management decisions at the national and international level.”