Tiny but Toxic: Stranded Whales Test Positive for Domoic Acid Toxicosis

It’s June 6th, a warm and windy afternoon at Sunset State beach. Guarded to the east by rows of coastal strawberry fields, the sand stretches out across Santa Cruz County before disappearing into mist below Moss Landing’s sleepy power plant spires to the south. Año Nuevo Island crouches at the northern horizon.

The California current, tides, and timing elected this place as the final stop for a humpback whale carcass. Waves slither around the slick figure, causing the gulls perched on it to jump. Its body is black with an underside speckled white, like a Jackson Pollock painting. Algae clings to tubercules at its chin.

Photo Credit: Keiki Sunderland

Hours earlier, a team of researchers from local universities and institutions necropsied the carcass. Fleshy openings and square-shaped wings of blubber and skin mark the traces they left from their sample collection process. Their work is urgent; another whale washed up less than ten miles south, two days earlier.

After analyzing the samples collected from both carcasses, the researchers announced their findings in briefs to the public. They had encountered the same toxin in both whales, in concentrations likely to have impaired one and nearly certain to have killed another. High concentrations of domoic acid had recently passed through San Francisco and Monterey Bays, and the carcasses carried receipts.

Decoding Domoic Acid: What is it, and how does it affect marine life? 

Domoic acid is a chemical cocktail that mimics the effect of the brain’s naturally occurring neurotransmitters. When ingested, it binds to nerve receptors like those concentrated in the brain’s hippocampus, triggering the release of positively charged ions into nerve cells. This overwhelming influx of charged particles causes the cell to swell and die. This process flows from one exposed cell to another via a cascade of activation, where neurons fire off signals like  machine guns with stuck triggers.

Symptoms of domoic acid’s neurotoxic effects appear in a host of predators with seafood diets, including seabirds, marine mammals, and humans. Known as amnesic shellfish poisoning in humans, around 0.66 milligrams of domoic acid per kilogram of a person’s body weight can induce symptoms like headaches, fatigue, and intestinal discomfort. Higher concentrations of the neurotoxin induce memory loss, confusion, hallucinations, seizures, brain lesions, coma, and death. The illness runs its course on varying time scales between species, staying in the body from hours to weeks before leaving the body in urine.

Scientists hold a group of marine algae from the Pseudo-nitzschia genus responsible for producing this poisonous neurotoxin. As smaller predators like krill or filter-feeding shellfish feed on the algae, they consume traces of domoic acid. The toxin gathers as it trickles up the food chain until it ends up in the belly of a whale, or on a dinner plate at a seafood restaurant.

Photo credit: Ben Philips

When is Domoic Acid Poisoning Most Common? 

While predation and sparse resources normally limit Pseudo-nitzschia’s numbers, combinations of ideal environmental conditions open the door for both harmful and benign algal species to thrive. Increases in wind speed, sunlight exposure, and nutrient input can aggravate domoic acid concentrations in seawater and cause what is known as a harmful algal bloom. These blooms instigate most reports of domoic acid poisoning.

 This was likely the case in February of 2025, when scientists suspect nutrient-rich ash from the Palisades fire in Los Angeles may have fed a massive bloom, causing hundreds of sea lions and dolphins to strand with symptoms. The impacts of these blooms are severe; over the last 20 years, 40% of unusual mortality events across the United States have been attributed to harmful algal blooms.

Climate change exacerbates the issue. Warming seas and severe weather can stir more nutrients in the water column, aggravating the frequency and intensity of blooms. Over the last 30 years, harmful algal blooms occurred once or twice within a decade; in Southern California, harmful blooms have been documented impacting wildlife for the past four years straight.

As Pseudo-nitzschia blooms become more common and severe, populations of species most susceptible to domoic acid toxicosis may not be able to recover. Fisheries on the West Coast have already been forced to reduce seasonal operations during recent blooms, as in 2015 when the industry lost about $48.3 million for delaying the catch of Dungeness crab. More frequent blooms may soon permanently limit the availability of high-demand catches in consumer markets and subsistence fisheries.

Photo Credit: Tomas Malik

Creeping Frontlines and Exposure in the Arctic

Melting sea ice and warming seas have also extended the northern range of Pseudo-nitzschia’s suitable habitat. A collaborative effort from researchers at the National Oceanic and Atmospheric Administration (NOAA), Alaska Department of Fish and Game, and other institutions uncovered concentrations of domoic acid in samples from 13 species of stranded or harvested Alaskan marine mammals. Of the 905 animals tested, the species most exposed to the toxin included bowhead whales, harbor seals, walruses, harbor porpoises, and humpback whales. Concentrations of domoic acid found in the sampled whales, bearded seals, spotted seals, walruses, and otters tested near those found in symptomatic California sea lions, suggesting environmental domoic acid may already impact the health of arctic mammals.

While the north’s resident ice seals may accumulate environmental domoic acid throughout the year, Alaska’s migratory visitors’ unique life histories put them on a crash course toward illness. Humpback whales migrate north to productive waters after wintering in the tropics to breed. Their timing coincides with annual phytoplankton spikes, allowing them to spend the year’s warmest months reaping swathes of fish, krill, and small invertebrates in plentiful waters fueled by algal blooms. This strategic behavior may soon become a roll of the dice; if the whales arrival coincides with a Pseudo-nitzschia bloom, they could find themselves swimming into a poisoned feast.

If domoic acid exposure becomes more common in Alaskan waters, symptomatic animals could be more vulnerable to ship strikes and other dangers or accumulate the neurotoxin’s impacts year after year. Local subsistence hunters may also ingest the toxin. Few places on the planet contain the right combination of resources to support humpbacks and their marine megafaunal kin, and protecting the integrity of Arctic food webs from harmful algal blooms has become a key priority of regional management agencies.

Photo Credit: Marnoc

Sentinel Sea Lions Help Sound the Alarm

Scientists have learned most about the impacts of domoic acid poisoning from its most frequent victims. California sea lions live in large colonies along the west coast, hunting prey in nutrient-rich nearshore waters and returning to rookeries in the Channel Islands to pup in the summer. By sharing their feeding and breeding grounds with increasingly common blooms of Pseudo-nitzschia species, sea lions are especially vulnerable domoic acid toxicosis. Sea lions face an onslaught of severe symptoms and high acute mortality; during a Southern California bloom in 2022, 262 sea lions were identified as symptomatic over a 37-day period. Of 70 animals rescued by wildlife care organizations, only 6 were returned to the wild.

The now-yearly bloom coincides with the sea lions’ pupping season, forcing mothers to unwittingly expose their unborn pups to the toxin through their amniotic fluid and milk. These pups face a far more severe prognosis than the acute, prey ingestion-affiliated symptom set. Exposure during the second and third trimesters of gestation damages synapses in the young sea lions’ brains before they are fully developed, sentencing them to a lifetime of seizures and metabolic disruption.

Many pups experience delayed neurological symptoms. Brain scans of young, infected in-utero sea lions may not resemble the atrophied structures of adult victims until puberty at around four or five years old. This sudden decay coincides with another developmental milestone in the brain known as synaptic pruning. Symptoms can manifest in disorientation, repeated erratic behaviors, attention deficits, seizures, and comas.

Climate change and warming waters are projected to push the overlap between gestation and domoic acid exposure well into the first trimester for some pups. Research on early embryonic development in the sea lion’s brains is still needed to better understand the consequences of these early interactions, with urgent necessity. Learning more about sea lion development and in-utero impacts could reveal how amnesic shellfish poisoning may impact human mothers and their children.

Their strong, prompt reactions to domoic acid present in their environments has established California sea lions as sentinel species for detecting the toxin’s presence and threat to humans, like federally protected canaries in a marine coal mine. Their strandings are carefully monitored to give local and federal authorities information about potential seafood contamination.

Combatting Domoic Acid in Research and Policy

Coastal researchers are racing to build a broader knowledge base on harmful algal blooms and domoic acid. A program at University of California Santa Cruz currently monitors a captive in-utero exposed sea lion to trace her development throughout the course of her life, using brain scans and cognitive tests to better understand the animal’s symptom timeline.

Further research is also necessary to determine how domoic acid’s impacts may vary between and within species. The team in Alaska suggests further inquiry into the specific concentrations of domoic acid each species can tolerate before symptom onset, along with how to more accurately measure these concentrations. Other avenues of study include characterizing the impact of domoic acid on tissues outside of the brain and understanding the risk factors that may influence an animal or human’s[KS1]  prognosis.

Scientists are also studying the toxin-producing algae itself. Researchers at Scripps Institution of Oceanography recently sequenced Pseudo-nitzschia’s genome, revealing the series of different enzymes coded by the algae’s DNA to synthesize the toxin. Learning more about the chemical and genetic infrastructure of Pseudo-nitzschia could open the door for opportunities to cut its toxin-producing ability out of its repertoire. Continuous monitoring of ocean temperature, wind, and the variation in plankton species in a region also help predict whether a bloom of a harmful species like Pseudo-nitzschia australis will occur.[2] 

 

Collaborative efforts between fisheries, stakeholders, researchers, and communities are learning new ways to minimize costs and maintain effective planning strategies in unpredictable waters. Researchers from the University of California Davis, NOAA, and the University of Washington compared public opinions of how fisheries reacted to a bloom period from 2014 to 2016 in California, Washington, and Oregon. Washington’s survey results report trust between fisheries and stakeholders, attributed to the state’s devoted monitoring technologies and rapid public notifications. Lackluster responses in California and Oregon suggest a need for closer relationship between authorities and media outlets. These relationships between scientific authorities, fisheries, and consumers will be crucial in navigating bloom-provoked closures and shortages in the most cost and health-conscious manner. They offer opportunities for innovation; collaborative efforts between public and private sectors have already developed ways to detect blooms earlier and preserve uncontaminated meat on catches made during blooms.

Back on the Beach

As the tide rises, sand loosens its grip on the Sunset carcass. It may be buried in the sand or wash back out to sea, providing a nutrient boost to ecological communities wherever it finally lands. As the gulls return to roost along the whale’s stomach, a young sea lion hauls out nearby and sends the seabirds back into the sky. It appears thin and tired, squinting at the birds as it lays in the lapping water. It has a changing world to acclimate to, and so do we.

Reporting stranded marine mammals is one of the most helpful ways for citizens to assist research on domoic acid poisoning and ocean health. If you see a stranded marine mammal, consider informing the Marine Mammal Stranding Network by contacting one of the following regional hotlines:

For LIVE mammals in the San Francisco Bay:

The Marine Mammal Center, 415-289-SEAL

For DECEASED mammals in San Francisco Bay:

         California Academy of Sciences, 415-379-5381

For LIVE mammals in Santa Cruz:

         The Marine Mammal Center, Santa Cruz, 831-633-6298

For DECEASED mammals in Santa Cruz:

         Long Marine Laboratory, University of California Santa Cruz, (831) 212-1272

Resources

 

Cook, P. F., Reichmuth, C., Moriarty, M. E., Deming, A. C., Hoard, V. F., Field, C., & Gulland, F. (2026). Sea lions as a natural model for charting the developmental course following in utero exposure to domoic acid. In Harmful Algae (Vol. 153). Elsevier B.V. https://doi.org/10.1016/j.hal.2026.103066

Domoic Acid and California Sea Lions. Channel Islands Marine and Wildlife Institute. (n.d.).https://www.cimwi.org/domoic-acid 

Ekstrom, J. A., Moore, S. K., & Klinger, T. (2020). Examining harmful algal blooms through a disaster risk management lens: A case study of the 2015 U.S. West Coast domoic acid event. Harmful Algae, 94. https://doi.org/10.1016/j.hal.2020.101740

Farrugia, T. (2026, March 4). VAWS – Underwater Storms: How harmful algal blooms form and their impacts on Alaska’s oceans. Retrieved from https://uaf-accap.org/event/vaws-underwater-storms-habs/

Fimbres Wood, L. (2018, September 27). Domoic acid decoded: Scientists discover genetic basis for how harmful algal blooms become toxic | Scripps Institution of Oceanography. Domoic Acid Decoded: Scientists Discover Genetic Basis For How Harmful Algal Blooms Become Toxic. https://scripps.ucsd.edu/news/domoic-acid-decoded-scientists-discover-genetic-basis-how-harmful-algal-blooms-become-toxic 

Jiang, R., Fan, Z., Li, X., Yang, J., Sun, M., Jiao, B., & Wang, L. (2026). Molecular and Cellular Mechanisms Underlying Domoic Acid-Induced Neurotoxicity and Therapeutic Drugs: A Comprehensive Review. International journal of molecular sciences, 27(2), 867. https://doi.org/10.3390/ijms27020867

Krasner, A. E., Martinez, M. E., Field, C. L., & Fire, S. E. (2025). The Toxic Effects of Environmental Domoic Acid Exposure on Humans and Marine Wildlife. Marine drugs, 23(2), 61. https://doi.org/10.3390/md23020061

Lefebvre, K. A., Quakenbush, L., Frame, E., Huntington, K. B., Sheffield, G., Stimmelmayr, R., Bryan, A., Kendrick, P., Ziel, H., Goldstein, T., Snyder, J. A., Gelatt, T., Gulland, F., Dickerson, B., & Gill, V. (2016). Prevalence of algal toxins in Alaskan marine mammals foraging in a changing arctic and subarctic environment. Harmful Algae, 55, 13–24. https://doi.org/10.1016/j.hal.2016.01.007

National Oceanic and Atmospheric Administration. (2025, March 25). Early bloom of toxic algae off Southern California sickens hundreds of sea lions and Dolphins | NOAA fisheries. NOAA Fisheries News. https://www.fisheries.noaa.gov/feature-story/early-bloom-toxic-algae-southern-california-sickens-hundreds-sea-lions-and-dolphins

Peña, M. (2026, June 12). Toxic algal blooms linked to deaths of recently stranded humpback whales - news. UCSC News. https://news.ucsc.edu/2026/06/dead-whales-domoic-acid/

About the Author: Keiki Sunderland
After earning bachelors’ degrees in Ecology and Creative Writing from UC San Diego in 2025, Keiki Sunderland returned to her home in Los Gatos inspired to pursue a career in conservation science. She leaves boot tracks along the coastline as an ecological restoration volunteer at Año Nuevo State Park and helps collect data on stranded marine mammals at Moss Landing Marine Laboratories when she can. She loves exploring wildlife conservation and evolutionary biology in her nonfiction, fiction, and short comics. Keiki is grateful to share her passion for marine conservation with the San Francisco Bay community and hopes to hone her research skills in graduate school someday.

Keiki Sunderland began her career in conservation science as a research intern at UC San Diego, where she studied ecology and creative writing before graduating in 2025. She loves volunteering at Año Nuevo State Park, collecting data on stranded marine mammals in Monterey county, and making comics about evolutionary biology. 

Star Fallout: On the Status of Sea Star Wasting Disease along the California Coast

The tide shrinks along the rugged coastline of Montara, California, quietly pulling back its saltwater curtains and revealing its precious treasures. Five ochre sea stars congregate between swathes of black mussels. Their slick mauve and amber bodies shimmer like gemstones clinging to the earth. Bright, colorful, and resilient; these creatures are the descendants and survivors of a near-apocalypse.

When Stars Fell

Photo Credit: Rosa Gil

In the summer of 2013, Sea Star Wasting Disease (SSWD) rippled a massive wave of sea star die-offs across North America’s Western coastline. The symptoms were grisly. Infected asteroids became freeze frames of an explosion caught on tape, their deflated bodies punched through by white lesions and organ-oozing gouges. Wastelands and ghost towns replaced the stars’ intertidal habitats as they lost billions–over 90%, in some species– of their inhabitants. 

The cause of such a devastating illness has been surprisingly cryptic. Over a decade after the beginning of the outbreak, research from the Hakai Institute in British Columbia recently isolated a strain of the bacteria Vibrio pectenicida as a causative agent of SSWD in sunflower stars. The bacteria, a close genetic relative of species causing cholera and flesh-eating infections in humans, is relatively new to science. V. pectenicida has yet to be tested as a direct cause of SSWD in any of the over 20 other species affected.

Other species in the Vibrio family multiply well in warmer waters, but without data on the geographic distribution of V. pectenicida, it’s difficult to understand where and how the species thrives. Researchers have observed more intense die-offs and slower population recoveries in Southern California compared to cooler Northern waters, but the timelines of mortality spikes and marine heat waves don't quite align. In fact, some sea star populations in Oregon were hit hardest following periods of cooler-than-average sea surface temperatures. It may well be that temperature changes don’t directly effect a population’s initial vulnerability to the bacteria, but aggravate the impacts of the pathogen.

Since that initial year of onslaught, infection rates have receded to chronic background levels between 2-4%. Recent knowledge may help explain why some stars have regained their places in tidal troves along the San Francisco-Monterey

Photo Credit: Abigail Sylvester

On Ochre Stars

The tidepool in Montara offers an opportunity to observe one of the most crucial species for California’s coastline, and one of  two sea stars most heavily impacted by Sea Star Wasting Disease. Found widely throughout California, ochre sea stars manage the diversity of tidal ecosystems by keeping their prey, mussels, from claiming too much space on rock formations. The stars can populate tidal zones in dense aggregations, reach sexual maturity at around five years old, and spawn in the spring or summer.

It only took two years for nearly all ochre stars on the west coast to disappear. Populations of ochre stars in Oregon lost between 59 and 84% of their pre- SSWD density, while sites sampled above the San Francisco bay lost from 9 to 81% of their total population between 2013 and 2015. Overall, the northern half of the stars’ range saw at least a 75% decrease in population density at nearly all sampled sites, with some of the most severe disappearances observed in and around the San Francisco bay. Regional differences in the magnitude of these losses don’t appear related to the stars’ densities within their populations; stars could still transmit the illness from far apart.

The Recovery Generation

At most northern sites, these bludgeoning losses were followed by monumentally large reproduction events. Surveys along the coast during the years following the outbreak reported 7,400%  increases in young sea stars in Northern California and an average 8,100% increase among Oregon sites. 

The mass- settlements of young sea stars, called ‘recruitment pulses’, flipped the population pyramid on its head. Most new recruits don’t normally stand a chance against their elders; as inheritors of their parents’ barren landscapes, the small stars likely thrived without competition from older individuals for resources. Despite their numbers, the new generations couldn’t make much of a dent in the resurgent mussels, which had capitalized on the sudden absence of one of their predators. Despite overshooting their pre-SSWD numbers at many northern populations, the ochre sea stars bear the burden of rebuilding top-down control of their prey and regaining stability in a post-apocalyptic landscape.

Photo Credit: Abigail Sylvester

A Genetic Edge

Scientists wondered wether survivors of the epidemic carried resistance in their genes. After sequencing the genomes of pre-disease adults, post-disease adults, and new recruits, researchers at UC Merced determined that young and established ochre stars surviving in the years after 2013 had a significant, unilateral  shift in their DNA compared to the pre-SSWD generation. Sea Star Wasting Disease had induced a bout of natural selection on the ochre star, sparing more resistant survivors. These survivors had passed this resistance on to the new recruits. 

The survivor stars also appeared to maintain a high degree of genetic variation relative to the pre-disease population, a hallmark of healthy, resilient generations. Despite their losses, a large, diverse population exists, providing the blueprints needed for the stars to adapt. 

On Sunflower Stars 

Back in Montara, another species is notably absent from the seaside gallery. The sunflower sea star, once widespread throughout the west coast, lost over 90% of its total population during the outbreak. These four foot wide, 24-armed goliaths served as the formidable guardians of California’s kelp forests, defending their ecosystems from the cascading effects of sea urchin overpopulation. Without predation pressure from sunflower stars, urchins overgraze the kelp, deconstructing their ecosystem into an evacuated water column and a barren seafloor– another wasteland altogether. 

Without the booming and busting recruitment episodes of the ochre star, sunflower stars have been slow to recover. The species showed symptoms before any other when Sea Star Wasting Disease arrived in a community and has become functionally extinct south of Monterey. Evidence from star populations in Washington suggests that sunflower stars may be sensitive to seasonal flare-ups in the disease during the Fall and Winter. The International Union for the Conservation of Nature declared sunflower stars Critically Endangered in 2021.

Rescuing a Giant

With billions of individuals stripped from the breeding population, the potential for a spontaneous recovery in the wild is unlikely. Aquarists and scientists have set to work on solving the problem of sunflower sea star immunity; one group hopes to breed immune stars, while the other looks to their environment for answers.

In San Francisco, researchers at California Academy of Sciences have begun working with partners like The Nature Conservancy and the National Oceanic and Atmospheric Administration to develop a breeding program for sunflower sea stars. Like those found in ochre stars, the researchers hope to uncover resistance-favoring genes in the sunflower stars’ DNA, with an eventual goal of re-introducing immune individuals into the wild. In the short term, their plan includes breeding and distributing sunflower stars to research facilities and aquariums nationwide, spreading public awareness and building up a reserve population.

Further up the coast, researchers from the University of Washington have turned their attention to the disease-causing bacteria itself in search of answers. The team has begun tinkering with the interaction between water temperature and bacterial concentration in the hope of finding a tolerable threshold for the sunflower stars, as well as surveying the west coast for areas of particularly high bacterial concentration. As this research develops, collaborative efforts between organizations may learn more about possible tools to use to attack the bacteria or mitigate its impacts on wild stars. 

The improbable is also not impossible; communities of sunflower stars have recently been sighted by scientific divers and the eagle- eyed public, raising questions about the possibility of an undiscovered immune population.

Outlooks on an Outbreak

Seven years before the COVID-19 pandemic, sea stars fell off of the west coast in droves. Disease ecology skyrocketed to the front of public concern in 2020, bringing with it the recognition of mass-infections as serious threats to the wellbeing of humans and animals. As researchers launch collaborative efforts investigating the interplay of temperature, population density, and genetic variation on the survival of sea stars, their findings have the potential to inform collective knowledge beyond tide pools and kelp forests. 

Citizen scientists have the opportunity to participate and aid these foundational research efforts by logging any sea stars they find in databases like UC Santa Cruz’s Multi- Agency Rocky Intertidal Network and iNaturalist. Organizations like California Academy of Sciences also host volunteer survey events.

Resources

Dunagan, Christopher. (2025, October 13). With One Mystery Solved, Researchers Examine 

New Strategies for Sea Star Recovery. Salish Sea Currents Magazine. www.eopugetsound.org/article/one-mystery-solved-researchers-examine-new-strategies-sea-star-recovery 

Gravem, S. A., & Menge, B. A. (2025). Metapopulation-scale resilience to disease-induced mass 

mortality in a keystone predator: From stasis to instability. Ecosphere, 16(10). https://doi.org/10.1002/ecs2.70426

Miner, C. M., Burnaford, J. L., Ambrose, R. F., Antrim, L., Bohlmann, H., Blanchette, C. A., 

Engle, J. M., Fradkin, S. C., Gaddam, R., Harley, C. D. G., Miner, B. G., Murray, S. N., Smith, J. R., Whitaker, S. G., & Raimondi, P. T. (2018). Large-scale impacts of sea star wasting disease (SSWD) on intertidal sea stars and implications for recovery. PLoS ONE, 13(3). https://doi.org/10.1371/journal.pone.0192870

Prentice, M. B., Crandall, G. A., Chan, A. M., Davis, K. M., Hershberger, P. K., Finke, J. F., 

Hodin, J., McCracken, A., Kellogg, C. T. E., Clemente-Carvalho, R. B. G., Prentice, C., Zhong, K. X., Harvell, C. D., Suttle, C. A., & Gehman, A. L. M. (2025). Vibrio pectenicida strain FHCF-3 is a causative agent of sea star wasting disease. Nature Ecology and Evolution, 9(9), 1739–1751. https://doi.org/10.1038/s41559-025-02797-2

Schiebelhut, L. M., Puritz, J. B., & Dawson, M. N. (2018). Decimation by sea star wasting disease 

and rapid genetic change in a keystone species, Pisaster ochraceus. PNAS, 115(27), 7069–7074. https://doi.org/10.6071/M3WW84

Amazing Species: Sunflower Sea Star. (2021). The IUCN Red List of Threatened Species. 

nc.iucnredlist.org/redlist/amazing-species/pycnopodia-helianthoides/pdfs/original/pycnopodia-helianthoides.pdf

Ochre Sea Star. (n.d.). Marine Species Report Card. 

www.aquariumofpacific.org/reportcard/info/ochre_sea_star

Sea star wasting disease. (2026, April 21). Multi-Agency Rocky Intertidal Network. 

marine.ucsc.edu/research/sea-star-wasting/

Sunflower sea stars. (n.d.). California Academy of Sciences. 

www.calacademy.org/about-us/sustainability-in-action/breeding-programs/sunflower-sea-stars

Highlights from Dr. Roxanne Beltran’s Talking : "Unraveling individual and environmental drivers of variation among elephant seals"

We had a technical problem and sadly the February talk was not recorded so here are highlights from the speech.

February’s fascinating talk was attended by well over one hundred ACS chapter community members to hear from Dr. Roxanne Beltran and researcher Conner Hale relate their research "Unraveling individual and environmental drivers of variation among elephant seals". Due to a technical failure we are unable to provide a recording but are sharing these video links for further interest: 1) 2025 PBS feature, 2) 2024 Science Magazine feature, or 3) Roxanne's Kraw Lectures of 2022 and Slug and Stein Lecture of 2023.

We encourage those interested in keeping up with the cutting edge research underway at the Beltran Lab to subscribe to their newsletter here. And a snippet of the lively Q&A that ensued follows.

·      How do researchers identify ES that arrive in various haul-outs?

Researchers at various California Elephant seal rookeries have agreed to use color tags to mark their locations. For instance, Pt. Reyes uses only pink tags; Ano Nuevo only uses green tags; the Marine Mammal Center uses orange tags for its rescued elephant seals. That is how researchers know that juvenile ES from Ano Nuevo have been seen at the Channel Islands, San Simeon, and Pt. Reyes haul-outs.

·      Can elephant seals differentiate between fish-eating orcas versus mammal-eating orcas?

Answer: Unknown

Biggs orcas, which hunt marine mammals, go completely silent during hunts to avoid detection by their prey. Resident orcas, which primarily eat fish, use echolocation clicks to locate their prey. Elephant seals eavesdrop on deep echolocating cetaceans (i.e. orca, dolphins, beaked whales) and may follow these cetaceans to find prey in the deep Mesopelagic Zone of the oceans.

·      How do elephant seals avoid predation by Orcas when they are swimming back from Alaska to California?

Answer: One behavior observed and recorded on the tags is that elephant seals do respond to Orca sounds by diving deeper away from the surface.

·      Regarding an elephant seal’s weight gain in a foraging trip, Conner offered this:

“I calculated the BMI of a seal that wore a tag during the post-molt foraging trip, and at deployment her BMI was 41, and at recovery her BMI was ~75! She went from 290 to 524 kilograms.” Some female elephant seals consistently gain up to 100kg of weight when pregnant. Beltram Labs’ research showed that increased weight gain correlated with lifetime reproductive success. Females that gain weight consistently have heavier weanlings, which have a better chance of surviving.”

If people are interested in donating to the Beltram Lab in Santa Cruz, here is a direct link:

https://give.ucsc.edu/campaigns/38026/donations/new?designation=a1K8c00000i24K3EAI