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 newly collected female wild white abalone releases eggs during the captive breeding program’s annual spawning event. This was the first new genetic input in the captive population for 14 years. Photo taken for CDFW by M. Ready

At nearly 130 feet underwater, CDFW abalone researcher Dr. Laura Rogers-Bennett didn’t have much time. Her dive computer told her it was time to ascend, which meant that she would have to stop searching for the endangered white abalone hiding in the waving fields of red and gold gorgonians.

Reluctantly, she watched the beautiful scene drop away below her as she kicked slowly upwards. She moved through the towering elk kelp towards her safety stop, a precious white abalone kept solidly in her grasp. On that trip, back in 2004, Rogers-Bennett and Ian Taniguchi, another CDFW abalone expert, and a team of other scientist divers collected 21 critically endangered white abalone off the deep reefs in the Channel Islands. This collection trip was conducted in an effort to save the species before they disappeared from the wild, and to create a captive breeding program that could bring this important and iconic species back from the brink of extinction.

Fourteen years later, the white abalone Captive Breeding Program is a thriving reality, thanks to the vision and hard work of a committed team of scientists from the White Abalone Consortium (WARC). Those 21 animals that Rogers-Bennett helped to collect in the Channel Islands have now produced thousands of descendants in captivity. The program is so successful, in fact, that it is now producing more animals than it has space to raise. Now, the next step is for WARC and CDFW scientists to perfect methods to release these captive bred animals back into the wild.

A huge challenge for CDFW and the WARC is to ensure that the captive-bred animals stand the best chance for survival in the wild – and one of the greatest obstacles could lie within the abalones’ own DNA. Because the entire captive-bred population stems from only 21 animals, the genetic diversity of the captive program is limited. One of the main factors that influence how a population of animals will react to stress is how genetically diverse the individuals are from one another. 

In the past, wild, healthy white abalone populations had large numbers of individuals to reproduce with. This created a vast number of family lineages and resulted in an expansive genetic pool. A population with diverse genetic parentage strengthens the overall population by ensuring that there will be a diversity of responses among the individuals. For example, some stresses, like disease or environmental change, may affect certain individuals while others maybe be more genetically suited to defend against those threats. If the population faces a major disease outbreak, some individuals will likely survive, enabling the populations to restore itself over time. But if a population lacks this genetic diversity due to limited parentage, the entire population could succumb to the disease.

The solution is to introduce new animals into the captive breeding population in order to diversify the gene pool and create animals vigorous enough to thrive in the wild. Yet that’s a trickier proposition than one might think, because of their endangered status. Even when evidence strongly suggests that there has been zero reproduction, researchers follow very strict guidelines so as not to disrupt potentially viable populations. For this reason, WARC and CDFW spent years monitoring reproduction of wild white abalone populations, until they were absolutely certain that the animals were not reproducing in the wild.

In 2017, the WARC was given a permit by NOAA to collect wild animals for the captive breeding program. The following May, when conditions were right, Rogers-Bennett and the WARC team of scientists returned to the Channel Islands on the first white abalone collecting trip in more than a decade. WARC divers gathered in the spring sun on the deck of the research vessel Garibaldi to discuss the day’s dives, which would be to nearly 120 feet. Everyone was focused, but a cautious optimism hung in the air. Encountering the incredibly rare white abalone was a long shot, but two individuals had been spotted in the area within the last year.

Alongside her team, Rogers-Bennett descended through the water column, watching as the ocean floor came into focus below her. As she got closer, she could just make out the familiar shape of an abalone. She assumed it was another, more common species of abalone, but as she got lower she recognized the unmistakable markings of a white abalone. She had landed directly on top of one!

Since the beginning of 2017, 10 animals have been collected by WARC scientists and transported to their facility in Bodega Bay. This is the first time in 14 years that scientists will be able to add new genetics to the captive breeding program. Dr. Kristin Aquilino, Director of the UC Davis Captive Breeding Program for the WARC, was able to include a newly collected female white abalone into the 2017 annual captive breeding spawn. It takes time before wild animals are able to integrate into the program, but researchers hope that the newly collected animals will participate in the next white abalone broodstock spawn.

With the new genetics from the wild abalone being introduced to the captive breeding program, and restorative stocking studies underway, the future for this species is looking brighter all the time. Through the dedication of a brilliant team of scientists, policymakers and an engaged public, the WARC is hopeful that one day the white abalone will resume its ecological role in the deep reef ecosystems of the beautiful Southern California kelp forests.

Please stay tuned for more updates about the white abalone and our other abalone restoration work in California!

CDFW Photos. Top Photo: CDFW diver Ian Tanigucci takes notes before collecting a wild white abalone (in the foreground) in 2017. This is one of 10 white abalone collected from the wild to be integrated into the captive breeding program at Bodega Marine Lab. These newly collected animals will provide a new and much needed source of genetics for the captive bred white abalone populations.

WARC diver Shelby Kawana assesses habitat at one of the CDFW red abalone stocking sites located off the coast of southern California.


WARC diver Armand Barilotti assesses habitat at one of the CDFW red abalone stocking sites located off the coast of southern California.


Octopus are a top abalone predator and therefor pose a threat to newly stocked juvenile red abalone populations. Researchers catch and relocate octopus when they are found hiding in crevasses near stocking sites.


A rediscovered stocked red abalone was found clinging to the underside of a rock during a one year post stocking survey.

Harvesting abalone for dinner used to be as fundamental to a Southern California lifestyle as fish tacos and flip-flops. But by 1998, a combination of overfishing and disease led to the closure of all abalone fishery south of San Francisco. By 2001, the white abalone was listed as an endangered species because populations continued to decline despite protection from fishing pressure. Population numbers are so low today that the only option for recovery is believed to be through a robust captive breeding and stocking program.

Scientists from the California Department of Fish and Wildlife (CDFW) White Abalone Recovery Project and their partners in the White Abalone Recovery Consortium (WARC) are working to bring back the iconic white abalone from the brink of extinction. Since 2016, CDFW and partners have been working to actively restore abalone populations through stocking of young captive-reared abalone. Successful stocking is the critical next step to reestablishing self-sustaining wild populations of this culturally and ecologically important mollusk. The early stocking studies have aimed to perfect the methods that will be used to restore wild white abalone populations in the future by using red abalone as a test case. Red abalone, a sister species of the white abalone, lives in the same deep kelp forest habitats, and their populations in Southern California have also been very slow to recover.

Every few months, scientific divers on board the CDFW research vessel Garibaldi wrestle into thick neoprene wetsuits and load heavy steel tanks onto their backs in order to check on the stocked abalone. As the divers descend deeper into the kelp forest, they enter the world of the white abalone. Sunlight streams through the towering giant kelp, briefly illuminating the shiny sides of the small fish taking cover in the kelp blades. Lobsters and octopuses are tucked into the crevices of rocks, and abalone and urchins shelter in the shadows. Many of those abalone are adorned with small brightly-colored numbered tags that identify them as the new additions to the neighborhood. After a few months in the wild, the stocked abalone can show an extensive amount of growth which speaks to the quality and abundance of resources in their new habitat.

Since restoration stocking began in 2016, the partnership has stocked close to 10,000 red abalone off the coast of southern California. These studies are helping scientists understand how stocked abalone interact with their new environment in the wild. Researchers are increasing the effectiveness of future stocking work by teasing out the risk factors that abalone face in their new environment. For multiple years after releasing the abalone, divers track the number and identity of each abalone, and assess the ecosystem health and predator abundances at each site. The divers also collect any abalone shells encountered to determine the effects of different predators at each site through time.

Octopuses, lobsters, sea stars and fish are all major predators of the young abalone, and care is taken to introduce the abalone during times of the year when the predators will be least abundant. All of the data from these early studies are aimed at lessening the risks that stocked abalone face, and to improve long-term growth and survival.

The WARC understands that abalone are at the heart of coastal California’s identity and culture. The return of red and white abalone to the wild marks the beginning of a new chapter in the love story between California and this amazing mollusk. This is true for the ecosystems that rely on them as well as for the humans that cherish them. Please stay tuned for updates on the lessons learned from these studies, and plans for upcoming white abalone stocking work!

For more information, please visit the following pages:

• UC Davis Bodega Marine Laboratory’s White Abalone Captive Breeding Program
• Journal of Shellfish Research, Vol. 35, No. 3: “Implementing a Restoration Program for the Endangered White Abalone (Haliotis Sorenseni) in California”

CDFW Photos. Top Photo: Newly tagged red abalone that are ready to be released into the ocean during a WARC stocking study in 2016.

California’s coastal waters are home to seven species of abalone, and all but one are endangered or listed as species of special concern. The white abalone in particular has been nearly decimated by overfishing and disease, and scientists can find no evidence that the remaining population is reproducing in the wild. In order to avoid loss of the entire species, CDFW and partner agencies have formed the White Abalone Recovery Consortium, which will employ captive rearing and restoration stocking efforts and extensive public outreach in order to save these animals from extinction. It will be an ongoing, long-term project, but all signs point to future success – already there are more white abalone thriving in the captive breeding program than the entire population living in the wild.

Read more about the efforts to restore California’s white abalone – and learn what you can do to help! – on the CDFW Marine Management News Blog.

California’s recreational fishery resource provides a huge benefit to the state’s economy. In the latest issue (102-3) of the scientific journal California Fish and Game, Reid et. al tackles the difficult task of quantifying the economic value of California’s recreational red abalone (Haliotis rufescens) fishery.

Using data for the 2013 season at more than 50 sites in Sonoma and Mendocino counties, the authors used the travel-cost estimation method to determine a value. According to their findings, the 31,000 people who fish for red abalone provide an economic benefit to California of between $24M and $44M annually.

The lower figure was derived solely by determining the costs involved in driving to the fishing locations, while the higher figure considers the time spent on the fishing activity. The data reveal three dominant criteria used to select fishing sites: 1) the presence of a harmful algal bloom — and the resulting stricter fishing regulations — in Sonoma County; 2) protection from ocean swells; and 3) the presence of recreational conveniences such as restrooms and boat launches.

Determining the economic value of the red abalone fishery puts into perspective the importance of managing it for sustainability. Other articles in this issue focus on management implications for California halibut (Paralichthys californicus) and Olympia oysters (Ostrea lurida).

Lesyna and Barnes report that California halibut reach physical maturity at different sizes and ages, depending upon location. Macroscopic examination of specimens revealed that, although all halibut were mature before reaching the commercial and recreational minimum legal size limit, central California halibut are larger and older by the time they reach physical maturity than their southern California counterparts.

Moore et. al studied the sexual development and symbionts of Olympia oysters (Ostrea lurida) that settled naturally on artificial clutches placed in San Francisco Bay. The results of the study suggest that Olympia oysters have the capacity to flourish when suitable habitat is available.

Collectively, these articles demonstrate the importance of studying natural resources for their consumptive and non-consumptive value.

According to California Fish and Game Editor-in-Chief Armand Gonzales, the articles provide critical direction for resource management. “It is therefore incumbent upon us as scientists, to keep working, keep studying and keep reporting what we see and find.