Science Spotlight

Purple urchins grazing a desolate kelp forest, Fort Ross, 2015. (Photo credit: A. Weltz)


Purple urchins consuming bull kelp fronds and stipes and crowding out native red urchins and abalone.


Unusual photo of abalone and purple urchins consuming bull kelp stipes. (Photo credit: A. Maguire)


Large aggregations of purple urchins are wiping out kelp forests, creating pink barrens and out-competing other species, such as abalone, for food. (Photo credit: A. Maguire)


Aftermath of the harmful algal bloom: dead abalone and other invertebrates washed up on shore at Fort Ross in 2011. (Photo by N. Buck)


Shrunken abalone due to lack of food, October 2015. The foot (meat) of the abalone should be roughly the same size as its shell. (Photo credit: S. Holmes)

The view of northern California’s beautiful coastline has historically been pristine and breathtaking. With dense kelp forest canopies blanketing the surface of the nearshore areas and protecting the abundant rockfishes, red abalone, sea stars and red urchins that lived below, it was a healthy, natural ecosystem rich with thriving inhabitants. Unfortunately, the ocean is now changing, and this idyllic scene is no more. But California Department of Fish and Wildlife (CDFW) marine scientists, citizen scientists and grassroots groups are all coming together to help turn back time.Their immediate focus is to eradicate the ever-increasing purple urchins.

For thousands of years, canopies of thick bull kelp (Nereocytis luetkeana) could be found along the coast of northern California, creating a rich subtidal home for the many fishes and invertebrates that lived and thrived in this region of the state. Today, bull kelp forests should be the foundation of our nearshore coastal ecosystem. The floating canopy of this brown algae gives shelter to young fish and sea stars, and the kelp itself provides food for valuable species, such as red abalone and red sea urchin.

Unfortunately, with the warming and changing ocean conditions in the last few years, scientists have noticed an alarming decline in these once prolific kelp forests. Though annually variable, in the just past five years, California’s kelp forests have declined by 93%.

In 2013, a mysterious wasting disease wiped out a large portion of the local sea stars in northern and central California. As a result, purple urchin populations exploded in the absence of the sea star, their main predator.

By 2014, a large patch of warm water developed off the coast, creating a catalyst that has further changed this underwater environment. The persistent warmer sea temperatures stress the kelp forests to the point that growth and reproduction have slowed dramatically and caused damage to remaining fronds and tissue.

But perhaps the most critical effect is that the purple urchin populations now thrive without their primary predators, and are left to graze the kelp unchecked. Purple urchins feed mostly on algae (like bull kelp) with beaks so strong that they can chew on everything from barnacles to calcified algae.

Along the north coast, purple urchins are now successfully outcompeting red urchins and abalone. The purple urchin population is now 60 times higher than normal. The areas that are now overrun by sea urchins with hardly any kelp left are referred to as “urchin barrens,” a type of ecosystem largely devoid of the biodiversity that used to flourish there. Due to this abrupt change, the seafloor now looks more like an underwater desert dominated by sea urchins, with little else alive.

“To address the impacts of the massive marine heat wave and kelp deforestation on the north coast we are going to need to shift our priorities and resources and come up with creative solutions,” says Dr. Laura Rogers-Bennett, a CDFW senior environmental scientist specialist based out of the Bodega Bay field office in Sonoma County. “I am encouraged that so many people and organizations are coming together in the Kelp Ecosystem and Landscape Partnership for Research on Resilience (KELPRR) collaborative and the "Help the Kelp" Campaign to promote kelp restoration in support of our kelp forest ecosystems and the human communities that make their living from the ocean.”

These negative effects reach from the ocean to the shore. Red abalone have been severely impacted by the loss of kelp and thus lack of food, causing the abalone fishery to close until at least 2021. Sea birds and marine mammals are also feeling the effects. With fewer fish available, the birds do not have enough food to feed their chicks. Reports indicate that 80% of black oystercatcher chicks and 90% of the local cormorant chicks are failing to survive. Harbor seals and sea lions are also hungry and feeling the effects.

In an all-out effort to address this devastating ecosystem change, scientists, management agencies and citizen scientists are all joining together to do everything they can to help. Their strategy is to harvest the purple sea urchins by hand to remove them from invading all of the substrate where bull kelp resides. By doing this they hope to create a network of healthy kelp patches along the coast.

Work is underway to create kelp refuge sites in North Caspar Bay, Noyo Harbor and Albion. This urchin removal project is a massive undertaking. Scientists hope also to try to develop commercial uses of the purple urchins, thus ensuring long-term sustainable harvesting.

Watermen's Alliance, a union of spearfishing clubs throughout the state, is coordinating urchin removal events this summer along the Sonoma and Mendocino coast using recreational divers wishing to assist with the purple sea urchin removals.

Next up will be the July 27-28 Purple Urchin Removal Event on Noyo Beach in Fort Bragg. They will need as many free divers and scuba divers as possible to participate, as well as kayakers to ferry full collection bags from the divers to boats and empty bags back to the divers. Just bring your dive gear or kayak gear and a valid California fishing license if you will be a diver removing urchins.

If you dive, boat, kayak or are just interested in helping, please contact the Noyo Center for Marine Science or Josh Russo with Waterman’s Alliance at (707) 333-9575 for details.

For more information about how to get involved, and stay up to date on kelp recovery efforts, please visit the following links. There are many opportunities for involvement, whether you are a scuba diver, freediver or just a concerned community member!

• ReefcheckCA - volunteer to help monitor coastal ecosystems
• “Help the Kelp” Program - Noyo Center for Marine Science
• Watermen’s Alliance - advocates for clean, productive and sustainable fisheries.
• Urchinomics: Focused on development of a commercial market for the purple urchin

Please join us for the next installment of the Conservation Lecture Series, “The Perfect Storm: Multiple Climate Stressors Push Kelp Forest Beyond Tipping Point in Northern California” by Dr. Laura Rogers-Bennett on Thursday, July 18 from 1:00 – 2:30 p.m. Dr. Rogers-Bennett will talk about the catastrophic decline of the kelp forests and the ecosystem it supports, including the red abalone and sea urchin fisheries, and the effects of climate stressors on northern California kelp forests. Register at www.wildlife.ca.gov/Conservation/Lectures.

This lecture will be held by webcast only. Members of the public can sign up using this registration link. For more information, please contact Whitney.Albright@wildlife.ca.gov or visit the Conservation Lecture Series website.

CDFW Photos. Top Photo: Unusual foraging behavior near Elk in Mendocino County: a large red abalone climbing a bare kelp stalk trying to reach fronds that are not there. (K. Joe)

Media Contact:
Carrie Wilson, (831) 649-7191

A new egg mat prior to deployment (CDFW photo by Marc Beccio)


Sturgeon egg mats deployed in a local waterway (CDFW photo by Marc Beccio)


Egg mats with Green Sturgeon eggs (CDFW photo by Marc Beccio)

CDFW biologists have been taking a new approach to looking at reproduction in one of the oldest fish species in existence.

Green sturgeon, which are listed as threatened under the Federal Endangered Species Act, are in effect a living fossil, having swam in both the fresh and ocean waters from California to Alaska for more than 200 million years.

They are a very slow-growing fish, typically living 60 to 70 years and reaching lengths of seven feet and weights of up to 350 pounds. Little is known about where they spawn in the Central Valley and how successful they are when they spawn.

In the spring of 2017, CDFW biologists began deploying egg mats in various rivers in the Sacramento Valley. In 2018, they documented green sturgeon spawning in the Yuba River for the first time, finding approximately 270 green sturgeon eggs on an egg mat deployed immediately below Daguerre Point Dam in Yuba County.

The egg mats consist of 3.5-foot by 2.5-foot metal frames that weigh about 20 pounds and are filled with a material similar to that used for a furnace filter. Mats are deployed by being gradually lowered to the river bottom from the bow of a boat. They are then retrieved by slowly hauling in the float line to avoid dislodging eggs stuck on the mat.

Unlike salmon and trout which dig redds and cover their eggs with gravel, green sturgeon females “broadcast” (release) their eggs into the water, which then sink to the river bottom, where their sticky surfaces adhere to various objects. Of eight egg mats deployed in the pool below Daguerre Point Dam, the biologists collected 270 eggs from just a single mat. As spawning locations can be difficult to identify, and eggs can be distributed broadly by the current within individual locations, documenting this spawning event was important.

A subsample of 33 eggs was retained to determine the developmental stage which will be used to calculate a spawning date. The mat was then lowered back to the river bottom. The 33 eggs collected represent about 0.02 percent of the total produced by a female green sturgeon of average size.

After confirming the presence of adult green sturgeon in the Yuba River, CDFW biologists believe the river may be important habitat for the species. Further research using these egg mats over the next several years will help fisheries managers identify critical spawning locations and habitat requirements for the future protection and enhancement of the species.

CDFW Photos. Top Photo: Green Sturgeon underwater. CDFW photo by Mike Healey.

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Media Contact:
Kyle Orr, CDFW Communications, (916) 322-8958

David Wright uses a mirror to reflect light into dark rock crevices in search of pika sign such as scat or urine stains. CDFW image by Joseph Stewart.


Joseph Stewart hikes through one of the mountainous locations in the northern Sierra Nevada that researchers searched for habitat that appeared suitable for pikas. CDFW image by Johanne Boulat.

CDFW staff recently conducted a study to determine whether American pika in California are able to find sufficient refuge from elevated temperatures in their natural habitat. Previous CDFW collaborative research and related work has suggested that pikas in California and Nevada have been declining in warmer areas, but some scientists contend that underground temperature refuges will protect pikas from warming temperature trends.

“The question of whether pikas are protected or exposed to warming temperatures seemed key to us,” said David Wright, a retired CDFW senior environmental scientist who co-authored the research with Joseph Stewart, a former CDFW scientific aid and now a University of California, Davis post-doctoral researcher. “It is central to whether or not climate change is going to push pikas to higher, cooler elevations and significantly reduce and fragment their range, in our state, on our watch.”

Pikas are small herbivores related to rabbits that live in fields of broken rock (talus) in the mountains of western North America. Researchers examined 46 mountainous locations in the northern Sierra Nevada with habitat that appeared suitable for pikas.  

Pikas prefer talus with rocks eight inches to three feet in size, and larger or less isolated talus fields are generally more likely to support pikas.

“We did our research at elevations both within and below the expected elevation range of pikas,” Wright said. “Lower elevations on average have warmer temperatures, which pikas don't tolerate well, but it's been suggested that talus provides a refuge from warmer temperatures. We wanted to look at this hypothesis.”

Two species of pika occur in North America, with only the American pika found within the continental U.S. With their high metabolic rates and thick fur (including inside their ears and on the bottoms of their feet), American pikas are well adapted to cold temperatures at high elevations. They do not hibernate during the winter, and spend the summer gathering grasses and wildflowers to store in “haypiles” for subsistence during the winter. Hikers may know them from their distinctive alarm call, a high-pitched cross between a chirp and a bark.

In 2010 to 2013, using small, year-round temperature recorders lowered approximately 1.6 feet to 3.3 feet into talus, along with visual surveys for pikas or signs of pikas, Wright and Stewart found that temperatures below the talus surface were buffered from warm and cold extremes of ambient air temperature. This was consistent with previous findings.

However, pikas were not found wherever talus temperatures were suitable. Temperatures within talus were mostly suitable for pikas across all the study sites regardless of elevation, yet pikas were absent from many of the sites. Instead, summer air temperatures proved to be the best predictor of pika presence or absence. The warmest sites had no evidence of pikas, followed by warm sites that had only remnant fecal pellets (pika pellets can persist among the rocks for decades), then slightly cooler sites that supported pikas in some years but not in others, to the coolest sites which supported persistent populations of pikas throughout the study.

“It’s not enough to have suitable temperatures in their underground burrows,” said Stewart. “Pikas also need suitable temperatures above ground where they forage for food.”

The authors concluded, based on their own and other research, that daily warm air temperatures may inhibit pika foraging and survival because they cannot tolerate the heat, and juvenile survival and dispersal may be similarly impaired by elevated summer high temperatures. Talus provides a cool refuge for pikas up to a point, but beyond that point pikas still need to forage and complete the portions of their life cycle that occur aboveground. This balance point, from this research, appears to be near an average warm season (June to September) air temperature of 71 to 73 degrees.

Funding for this research and similar CDFW efforts in the Sierra Nevada are supported by State Wildlife Grants administered through the U.S. Fish and Wildlife Service.

The study, Within-talus temperatures are not limiting for pikas in the northern Sierra Nevada, California, USA, can be viewed here (PDF).

CDFW Photos. Top Photo: Pikas are small herbivores that live in fields of broken rock (talus) in the mountains of western North America. CDFW image by Jan Dawson.

Media Contact:
Kyle Orr, CDFW Communications, (916) 322-8958

At Iron Gate Hatchery in Hornbrook, the fall 2018 spawning operation has just concluded. Iron Gate spawns both Fall-Run Chinook Salmon and Coho Salmon from the Klamath River. For Chinook, the hatchery staff manually collect the eggs and mix it with the milt immediately after the fish come into the facility. CDFW environmental scientists also collect heads from adipose fin clipped salmon, in order to retrieve implanted tags in the snout. The retrieved tags tell the biologists which hatchery the fish is from, and when it was released. They also collect scales, which enable them to determine the age of the fish.

For Coho Salmon, the process is a little more involved. The Coho are measured and samples taken, but the samples are sent off to a National Oceanic and Atmospheric Administration (NOAA) laboratory in Santa Cruz for analysis. While the samples are processing, the fish are kept in individually-numbered holding tubes at the hatchery. They will be spawned after the tissue analysis determines which fish are the best genetic match.

CDFW Photos

For more information about Iron Gate Hatchery, please visit: www.wildlife.ca.gov/Fishing/Hatcheries/Iron-Gate.

Media Contact:
Kirsten Macintyre, CDFW Communications, (916) 322-8988

Short Eared Owl. Courtesy of the National Digital Library.

Short Eared Owl. Courtesy of the National Digital Library.

Short Eared Owl. Courtesy of the National Digital Library.

Short Eared Owl. Courtesy of the National Digital Library.

A team of raptor biologists is working on a study of western populations of the Short-eared Owl – and are inviting members of the public to help collect and contribute important data as “citizen scientists.”

The project, known as the Western Asio Flammeus Landscape Study (WAfLS), is being conducted across eight western states, including Idaho, Montana, Nevada, Oregon, Utah, Washington and Wyoming, in addition to California. The purpose of the study is to determine the reasons for the sharp decline in Short-eared Owl populations – more than 60 percent over the last four decades across their western range.

“This project is a really unique and exciting collaborative effort to understand the species population on a very large scale,” said Carie Battistone, CDFW’s raptor biologist and WAfLS’ California State Volunteer Coordinator. “Given how wide-ranging – and in some cases, remote – the owls’ habitat is, we rely heavily on volunteers to help us collect the data we need.”

Battistone added that no special knowledge of raptors is needed in order for individuals to participate and contribute. “You don’t need to be a bird expert. You just need to have a keen interest in the outdoors and for the wildlife species that call California home,” she said.

The WAfLS project identifies 54 survey routes in California, all located within known habitat of the Short-eared Owl. “Citizen scientist” volunteers are needed to drive these routes, stop every ½ mile to look for and record owl presence and habitat features at each point. Volunteers will be asked to conduct two separate surveys on days of their choice during specified three-week survey windows in March through May. Each survey takes about 90 minutes and must be conducted during specified twilight hours, when the owls typically conduct their elaborate courtship displays.

Survey grids are located throughout much of the state from Modoc County in the north, Humboldt County in the west, Santa Barbara and Kern counties in the south and Mono County in the east. To view a map showing the grids for which volunteers are still needed, please visit the WAfLS website and click on “sign-up” on the right. The website also has a wealth of information on the project’s goals, as well as past reports, maps and volunteer resources (protocol, data sheets, etc.).

Battistone said that the information gathered by citizen scientists will be used by conservation experts and managers to design and implement strategies to help bolster populations of the Short-eared Owl.

“The project will help to determine what the Short-eared population numbers are like across the west, quantify how populations fluctuate spatially and temporally and identify how various factors – such as distribution, farming practices, grazing and climate – influence owls,” she said. “Once we have the data and resulting analyses in hand, we can make informed decisions on how to best protect and conserve the species.”

Owl photos courtesy of the National Digital Library. Top Photo: SEOW Survey: Surveying for Short-eared Owls can be a fun family activity. (CDFW Photo by Carrie Battistone.)

Media contact:
Kirsten Macintyre, CDFW Communications, (916) 322-8988