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The Otter and the Perch

Wild Times at Jewel Lake

by on April 11, 2012

A river otter eats a Sacramento perch in Jewel Lake at Tilden Park.

Photo by Jim Scarff.

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.

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Paola on April 12th, 2012 at 12:00 am

Nicely written piece and beautiful pics!

Littlefreedoms on April 13th, 2012 at 12:00 am

that cute otter looks like a dog with those big fangs!

baynature on April 13th, 2012 at 12:00 am

It sure does! Otters are related to weasels, so not so closely related to dogs, but they are both members of the order Carnivora (http://en.wikipedia.org/wiki/C…, and big canine teeth are characteristic of carnivores. Funny that we call those teeth canines (and dogs are canines too!). Cats, weasels, and of course otters have them too!

Bruceprt2005 on April 13th, 2012 at 12:00 am

I hope that there are no plans to remove the otters.

baynature on April 13th, 2012 at 12:00 am

Don’t worry! There’s no plan to do anything to remove the otters, which are, after all, just being good otters. The emphasis is on making the fish more resilient to these kinds of natural pressures.

Debbie Viess on June 24th, 2015 at 11:15 am

Hey Dan,
We have been up at Jewel Lake twice this past week, and viewed the most recent, adult male otter who is livin’ the good life as a weasely eatin’ machine! We have seen fish and huge crawdads, as well as some probable frogs, go down that otter gullet. The Park told me that duckling numbers are down too … down that otter hatch, they mean!
The real issue for the “edible” wildlife this year is the fact that Jewel Lake is more of a Jewel Pond right now, with extremely low water levels.

To protect that endangered perch and the red legged frog, the Park is prevented from dredging that lake to make it deeper; however, all of those species will be lost when it becomes a dust bowl.

That sleek otter is having a field day, though, and he will just move on to greener or should I say wetter pastures, once he has exhausted that food source or the water becomes too low.

For a mammal that supposedly hunts at night, he is sure active during the day!

Challenging times for both predators and prey.

No water, no aquatic life. Let’s remember to add in the very basic needs of all wildlife, endangered or not, when we decide to parcel out our water resources. We all deserve clean water to drink and/or breathe, depending on your physiology!

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