Purple sea urchins are spiny underwater invertebrates that look like pincushions. They’re native to the ocean along the California coast and share their home with sought-after delicacies like red urchin and abalone. Now, after a few years of rapid growth, some people are calling purple sea urchins a scourge.
Just after 8 am on a foggy morning on the Mendocino Coast, James Moskito helps a boatload of divers in wetsuits flip backward off his boat.
“Okay, air’s on, reg in the mouth?” He asks a diver. “Whenever you’re ready you’re good behind you.”
These divers will plunge down 30 feet into the cold water to scrape purple urchins off the bottom.
“You okay? Bars, bags.”
Moskito hands the divers abalone bars, which they’re repurposing for purple urchins today. Usually divers on this cove are picking abalone, but today they’re only taking purple urchins. Think of it like weeding for the ocean floor. Some use tools, some use their hands, and others have improvised — one woman carries a yellow kitty litter scooper.
“It’s just so I don’t have to grab them with my hands,” she says. Urchins are spiny, and their spikes are notorious for sticking people’s fingers.
Under our boat there’s usually a lush forest of bull kelp teeming with fish. Now the sea floor is carpeted in purple urchins — it’s called an urchin barren. A few urchins are normal, but this is out of control. They’ve eaten all the kelp that’s a food source in the cove. Now, even they are starving. But clearing purple urchins out of protected coves like this one could give kelp a foothold to grow back.
Nearly 100 divers from all over the state camp near the cove. Each morning they zip into neoprene suits and try and turn the tide on a collapsing ecosystem.
Matt Mattison is one of the divers camping out this weekend. He looks like a working man’s Neptune — wetsuit open to the waist and all kinds of spears in the bed of his truck. He runs a spearfishing group called Nor Cal Underwater Hunters.
“So the situation that is going on out here is the worst I’ve seen in 38 years of diving out here....We gotta do something.”
Mattison has been diving up and down the Mendocino castline since he was six years old. For most of his life, the ocean floor has looked different.
“I can remember the day when you would struggle to find the holes to dive in because there was so much kelp.”
For the entire underwater ecosystem to switch from kelp forest to a wasteland of spiky urchin in just a few years is unnerving for people like Mattison who spend a lot of time underwater.
“Ninety percent of coast has lost kelp resource. It’s not just the abalone — it’s the whole fishery. You’ve got no life on the rocks. Down there it’s like its been pressure washed with a pressure washer. Before everything was just covered in life.”
Purple urchins get painted as a bag guy here, but they’re just the most visible sign that the ecosystem is unhealthy. In 2014 a huge blob of warm water weakened the bull kelp forest. On this part of the coastline, bull kelp is food for a lot of marine life. Purple urchins are fierce competitors for what’s now a severely limited food supply. And if purple urchins eat it all, that means there’s none left for the abalone.
That’s bad news for Blake Tillman, who owns the Fort Bragg dive shop his father opened 40 years ago.
“Abalone diving has been a main part of our business for years our numbers are way down.”
Most years, Northern California has the largest recreational abalone fishery in the world. People come from all over to dive here. One study estimates that it’s worth $44 million dollars. This year the state says no one can dive for abalone. They’ve closed the season until 2020 to give the abalone a chance to grow back. The abalone are like canaries in a coal mine — they’re one of the first species in the ecosystem to be affected by the kelp loss. And for business owners like Tillman, that’s bad for the bottom line.
“This year I would say it’s so dramatic. Its like 75 percent down as far as people coming. It’s pretty huge. We offer other stuff at the shop so that’s kind of helping us.”
Dive shops are more than places to buy gear. They’re like the office water coolers of the diving community — hubs for news and gossip. While we’re talking, a steady stream of divers comes in to fill up tanks.
“I got a lot of friends who are business owners in town, restaurant owners, and they’re definitely feeling it.”
So diving tourism is slow and commercial divers don’t have work either.
But from one biologist’s perspective, this glut of purple urchins isn’t the end of the world. It’s just a thing that happens really rarely.
Dr. Steve Lonhart calls the urchin barrens another stable state. He would know — he’s a kelp expert who works for the Monterey Bay National Marine Sanctuary. He’s researching the barrens in a partnership with California Department of Fish and Wildlife to see if there are solutions for kelp recovery. He says that from a scientific perspective, the barrens are really interesting, but he acknowledges that they’re hard on coastal communities.
“This is something I read about in ecology textbooks and learned about as an undergraduate. And so basically I'm getting to see something that others have seen in the past.”
Urchin barrens have taken over coastlines before. In theory, this purple urchin ecosystem will flip back to normal.
“There's a lot of political pressure and pressure from the public to try and do something to see if it's even possible to change some of these urchin dominated systems back into kelp forests likely ahead of schedule because they will flip back just take time.”
But water temperature fluctuations like the one that killed the kelp are likely to happen more often; they’re part of climate change. And the diving community isn’t satisfied with a theory. They want to see healthy bull kelp come back now. So they’re working with California Fish and Wildlife to track their progress.
“You want to have a result that causes people to remain interested,” Lonhart says of the purple urchin removal effort.
“If you feel like you're part of a solution, you're more likely to keep doing it. If you feel it's going nowhere then you're going to move on to something else. So, having the fish and wildlife biologists associated with those is really important.”
People like diver Matt Mattison are willing to spend their weekends fighting for what they recognize as a healthy ecosystem.
“There are a lot of battles in a war and that’s what this is,” he says.
So people with diverse interests are banding together: commercial fisherman and recreational divers — who usually compete for ocean resources — are working towards a common goal.
“Historically where the whole dive community come together from abalone divers from spear fishermen to scuba to photographers to research divers. We’ve got every aspect of diving coming here to participate in these events which is just historic.”
It’s a small hope, but enough that divers have come from all over the state to pitch in. Even a crew of nearly 100 divers looks small on the cove — and they’re up against millions of urchins.
Out on the gray cove, a flotilla of volunteer boats bobs in the swell. They’ll pull over two tons of urchins this weekend — almost 60,000. A tiny dent on the total population, but maybe the small start of a big change. Brightly colored kayaks paddle back and forth between boats and the dark heads of divers, as they haul spiny bags from the bottom of the sea.
The next purple sea urchin removal event will be this weekend, November 2 and 3, at Van Damme Beach in Mendocino.
This story first aired in August of 2018.