We Have Time to Save Ocean Life from Extinction, but Only If We Act Fast
First the good news: Compared with the destruction humans have caused to animals on land, animals in the ocean are doing pretty well.
The bad news? We’re starting to make up for lost time, according to a new study published Thursday in the journal Science.
Humans have driven fewer than 50 marine animal species to extinction despite fishing for tens of thousands of years, compared with wiping out hundreds of land animal species in just the past few hundred years, “from famous species like dodos to obscure amphibians in rainforests,” said study coauthor Douglas McCauley, a marine ecologist at the University of California, Santa Barbara.
Now, however, we’re capable of bringing the same annihilating force to marine animals—by fishing and hunting and also by transforming ocean habitat through seafloor mining, aquaculture, pollution, and climate change–driven ocean warming and acidification.
“Marine extinction rates today look similar to the moderate levels of terrestrial extinction observed before the industrial revolution” of the 18th and 19th centuries, states the study. “Rates of extinction on land increased dramatically after this period, and we may now be sitting at the precipice of a similar extinction transition in the oceans.”
To make their case, McCauley and his colleagues outline three kinds of animal loss:
- Around 90 percent of the larger fish living just offshore have experienced some degree of “local extinction,” where a species disappears from a specific part of its range.
- North Pacific large whale populations dropped 80 percent to 90 percent from post–World War II hunting, to the point that they vanished from their spot in the food web as major killer whale prey. Killer whales have responded to this “ecological extinction” by serially decimating other prey species, such as sea otters and Steller sea lions.
- Hunting also crashed blue whale numbers in the Antarctic from around 239,000 to about 2,000 during the 20th century. We didn’t eradicate the blues, but they’ve survived in such small numbers that the species is “commercially extinct,” or unprofitable to hunt.
McCauley hopes people take the study as “a kick in the pants” to protect ocean life. “We’ve lost some of those opportunities on land,” he said, referring to species like the passenger pigeon and the golden toad.
The public must continue to press for climate change solutions, McCauley said, and also for more and bigger marine protected areas. That's because many marine species—such as bluefin tuna—range widely. These areas need to be put in the right places too. “In the oceans we have some sense of which areas will be good refuges from ocean warming and acidification,” he said.
“One thing that I hope is [that] readers go, ‘Wow, I didn’t realize that the state of wildlife in the oceans is what the state of wildlife on land was like several thousands of years ago,'" McCauley said. "We shouldn’t make the same mistakes underwater that we did on land."