The Otter and the Perch

April 11, 2012

For at least a year, we’ve been hearing about the river otters that occasionally show up in Jewel Lake, in Tilden Regional Park in the hills above Berkeley. They made it onto the Berkeleyside blog just last week.

But it wasn’t until we got a call from Pete Alexander, the fisheries biologist with the East Bay Regional Park District, that we realized there was more to this story than cute otters.

Otter eating perch

Down the hatch! Photo by Jim Scarff.

Photographer Jim Scarff contacted Alexander with the amazing photos we feature here, showing the otters chowing down on Sacramento perch, a California species of Special Concern. Turns out the Jewel Lake perch hold some rare genetic diversity that might be critical to the recovery of a species that once ranged throughout the Sacramento-San Joaquin Delta but is now confined to a few remnant populations in lakes and reservoirs.

Jewel Lake is artificial, formed from a dam on Wildcat Creek, and Alexander says the otters are most likely coming up Wildcat Creek from San Francisco Bay, though they could also be coming overland from San Pablo Reservoir.

This isn’t the only instance we’ve seen of cute otters proving their mettle as tough predators. In a 2007 page for Bay Nature, artist Jack Laws went to Rodeo Lagoon in the Marin Headlands to cover the story of a group of otters that had learned to hunt brown pelicans, which were then on the endangered species list.

It’s wild out there!

Alexander says he’s working with state wildlife officials on plans to transplant some of the Jewel Lake perch to other ponds in the park system, so this genetically valuable population isn’t so vulnerable to a few hungry otters. But that project is made more complicated by the fact that the perch themselves will eat the tadpoles of California red-legged frogs, which are protected as a threatened species under state and federal law. Nothing is simple.

Stay tuned for more on stories of the East Bay’s lesser-known native fish in a future issue of Bay Nature.

Otter eating perch

A last look at the world. Photo by Jim Scarff.

About the Author

Dan was editor of Bay Nature from 2004 until 2013, when he left to work for SF-based Stamen Design. He is now executive director of GreenInfo Network, a nonprofit mapmaking organization. A onetime professional cabinetmaker, he considers himself a lifelong maker of things and teller of stories. Dan has been working at the intersection of journalism and technology since, at age 16, he began learning reporting, page layout, and database design. His enduring interest in environmental issues crystallized into a career path in 1998 when he assisted former U.S. Poet Laureate Robert Hass in a cross-disciplinary nature writing and ecology course at UC Berkeley, from which Dan received a Masters in English literature. In 1999, he became Associate Editor of Terrain, the erstwhile quarterly magazine of Berkeley's Ecology Center. In addition to editing and art-directing Bay Nature magazine, he was also Bay Nature’s chief technology strategist, fixer of broken things, and designer of databases and fancy spreadsheets. And he was even known to leave the office and actually hike outdoors.