River Otter Rebound

Fifteen years ago, ecologist Megan Isadore was working in a creek just north of San Francisco. She noticed a family of sleek river otters paddling around and gobbling up crayfish. “It was exciting, because they’re attractive animals,” says Isadore. But there was a problem: According to maps published by state wildlife officials, these otters didn’t exist.

River otters once frolicked in waterways across North America. But fur trappers started hunting otters in huge numbers in the 1700s. Pollution in rivers and creeks also made it harder for the animals to survive. By the 1980s, river otters had mostly vanished from U.S. waterways.

Fifteen years ago, ecologist Megan Isadore was working in a creek. She was just north of San Francisco. She noticed a family of river otters paddling around and eating crayfish. "It was exciting, because they're attractive animals," says Isadore. But there was something odd about seeing them in that area. According to official wildlife maps, otters no longer lived there.

River otters once played in rivers and creeks across North America. But fur trappers started hunting otters in huge numbers in the 1700s. Water pollution also made it harder for the animals to survive. By the 1980s, river otters had mostly vanished from the U.S. 

But Isadore kept seeing otters in areas they’d previously disappeared from. Other scientists told her that they’d spotted the animals too. Isadore had a hunch that river otters were making a comeback, but there was no scientific evidence. In 2012, she co-founded the River Otter Ecology Project to change that.

Scientists with the organization set up cameras to monitor and count river otters. Volunteer “Otter Spotters” also  report sightings of the animals. Otter Spotters use an online form to note where and when they see river otters. 

But Isadore kept seeing otters in areas they'd previously disappeared from. Other scientists told her that they'd spotted the animals too. Isadore suspected that river otters were making a comeback. But there was no scientific evidence. In 2012, she co-founded the River Otter Ecology Project to change that.

Scientists with the organization place cameras near rivers. They use them to watch and count river otters. Volunteer "Otter Spotters" also report sightings of the animals. They use an online form to note where and when they see otters. 

The animals have been spotted in a creek behind a middle school and on shore near the Golden Gate Bridge. Isadore thinks that pollution cleanup and hunting restrictions have allowed the otters to move back into the San Francisco Bay Area. “Our theory is that they returned slowly and are still recovering,” she says.

Though the recovery is encouraging, it’s unclear what the future holds for river otters. Scientists don’t know, for example, how climate change might affect them. That’s why it’s important to keep paying attention, adds Isadore. “One of the fun things about studying river otters is that there’s still a lot to find out,” she says.

The animals have been spotted all around the San Francisco Bay Area. Some were seen in a creek behind a middle school. Others were resting on shore near the Golden Gate Bridge. Isadore thinks that cleaning up pollution and restricting hunting have helped the otters. These changes may have made the Bay Area a place that otters could live again. "Our theory is that they returned slowly and are still recovering," she says.

The recovery is a good sign, says Isadore. But it's unclear what the future holds for river otters. Scientists don't know how climate change might affect them, for example. That's why it's important to keep paying attention, adds Isadore. "One of the fun things about studying river otters is that there's still a lot to find out,” she says.