As humans hunt, their prey gets smaller: study

"The public knows we often harvest far too many fish, but the threat goes above and beyond numbers," Darimont said in a statement. "We're changing the very essence of what remains, sometimes within the span of only two decades. We are the planet's super-predator."

Regulations meant to protect the young may in fact be helping drive this unnatural process, Darimont said.

"Hunters are instructed not to take smaller animals or those with smaller horns. This is counter to patterns of natural predation, and now we're seeing the consequences of this management," he said.

(Reporting by Maggie Fox; Editing by Will Dunham and Eric Walsh)