Environment & Science

Beachcombing: To grow a new kelp forest, coastal partners remove urchins along Palos Verdes Peninsula [video]

Purple sea urchins the size of golf balls eat everything in their path, including the millions of kelp spores trying to take root on the ocean floor.
Purple sea urchins the size of golf balls eat everything in their path, including the millions of kelp spores trying to take root on the ocean floor.
Mae Ryan/KPCC

Listen to story

Download this story 1.0MB

This story is part of our summer series "Beachcombing," in which KPCC reporters will explore the ecology, economy and culture of Southern California's beaches and coast. Let us know what you think in the comments below or on KPCC's Facebook page.

A team of scientists, volunteers and fishermen is working to restore kelp forest in a patch of ocean off the Palos Verdes Peninsula. The $2 million four-year project aims to replace a small part of the southern California coastal kelp forests, most of which have been lost over the past century. The effort involves removing almost all of the purple sea urchins in a 150-acre area; the urchins have overrun the sea floor, eating up the kelp spores that seek to take root.

A large partnership

The small boat he’s on is pitching on current and swells three ways at once. At least one person is seasick. The temperature of the ocean at bottom off Rocky Point is probably 52 degrees Fahrenheit. But the director of marine programs for the Santa Monica Bay Restoration Foundation, Tom Ford, wriggles into his wetsuit while singing a sea chantey. He and Los Angeles Waterkeeper's Mike Quill start trading lines from “Jaws” as they joke about whether to wear a wetsuit at all.

“Oh yeah,” says Quill. “It’s like bathwater in here, brother.” He starts humming a tune about sunshine on a cloudy day.

“There’s a certain dance we have to go through out here to get ourselves psyched up to jump into the water,” Ford says. He’s the kind of guy who accentuates the positive. After all, it’s six whole degrees warmer at the surface. “Fifty-eight’s like going to Martinique. We just lay there like, oh this is great,” he says, laughing.

That dance is a necessary one. The Santa Monica Bay Restoration Foundation, with $2.5 million in financial support from the National Oceanographic and Atmospheric Administration, is leading the restoration project. Waterkeeper, Occidental College’s Vantuna Research Group, Heal the Bay, the California Science Center, and fishermen’s groups are helping. If they stay on schedule, with twice-weekly boat trips to the Palos Verdes Peninsula, these groups have four and a half years of work ahead of them to repaid damage done over decades.

An ecosystem out of balance

Development has fed urban runoff and other pollution into coastal waters, causing kelp to suffer. The small, spiny purple sea urchin has hampered kelp growth, too. “We are lacking kelp in many places here on the Palos Verdes Peninsula because there’s too many urchins down there,” Ford says.

Purple sea urchins eat everything in their path, including millions of kelp spores trying to take root on the ocean floor. But the urchins didn't become dominant overnight. People hunted the urchins’ predators, says Ford.

" The sea otters were hunted out locally by 1850," he says. "We have fewer sheephead as we used to and they’re not as big. Same thing with our lobster."

Now there’s little to slow urchins down. “It’s really a survival problem for the kelp,” fish biologist David Witting says. “They can settle and they can start growing, then they get eaten.”

To make room for the kelp to grow, Ford’s team is going to take out almost all of the urchins in this area.  

“The kelp plants we’ve got out here are adults, they’re making babies, they’re reproductively active, and if we allow these babies to settle in on these rocks here, with in a year they’ll be at the surface, pretty much looking like mom and dad,” Ford says.

Golf-ball sized purple urchins carpet a golf-course sized 150 acres of barrens. Every square meter holds around 70 urchins now. The restoration project will cut that number to two.

Killing to improve coastal marine life

In the years leading up to this project, researchers have surveyed and mapped the barrens. Now Ford, Quill and others are laying down 30-meter measuring tape, to mark quadrants along which they’ll work.

Ford waves their weapon of choice: a blue-handled hammer, already rusty after three weeks in the sea. “Hand drop-forged, Rockford, Illinois,” he reads, cheerfully. “Made in the USA.”

In the hands of divers, these hammers will kill nearly 5 million urchins. Volunteer Manny Chavez says he feels each one die under the hammer’s blow.

“It’s like a crunching noise,” Chavez says. He’s out here on vacation time from his day job at the L.A. Department of Water and Power. “You know, you ever step on a bug? You can hear the tapping against the rock with the hammer. The fish are happy. They love it.”

So do the biggest fans of the sea urchins on land – the guys who make a living off of them. They’re picking up hammers, too.

What’s good for the kelp is good for the urchin

“We’re really excited on our end,” says Bob Bertelli, the chair of the California Sea Urchin Commission. “We think it has tremendous merit.”

Bertelli says this effort to restore the kelp will make healthier urchins. Too many urchins means they’re too small and sickly to yield enough good roe, he says.

“Our industry is based on those animals being able to feed themselves and to develop a large enough roe recovery inside the urchin, that’s what we’re after,” Bertelli says.

Bertelli says a restored kelp forest will also mean even bigger red urchins, his industry’s main source of income. That’s especially important because the state closed some of the most productive urchin grounds a few years ago to create marine protected areas.

“We need to get more out of what we have, so this thing of rehabilitating areas is very important,” Bertelli says. “And I think we’re going to get a lot of very valuable science data out of this.”

Scientific modeling projects a dramatic increase in the number and the mass of all the fish, on the order of 300 percent. “For the commercial sea urchin harvesters who are partners in our project, our models suggest increases of something close to 900 percent returns when those kelp forests come back,” Tom Ford says. “Those are big wins.”

Where the purple urchin populations has been thinned, kelp is already starting to take root.