Stranded marine mammals are Silent Teachers

 More than H5N1 trcking

Studying the dead marine animals that wash onto Central Coast beaches can alert researchers to what’s affecting the seals, whales and others that live along the coast. Año Nuevo State Park had an outbreak of H5N1, Highly Pathogenic Avian Influenza, in elephant seals at in February. It didn’t affect elephant seals in the San Luis Obispo area, but seals and sea lions and other marine animals die of many other maladies. Their dead bodies are the focus of a non-profit established last fall, Central California Marine Animal Response Team.

Barbie Halaska, CCMART’s executive director and senior scientist, quotes eighteenth century anatomist Giovanni Morgagni, “This is the place where death delights to help the living,” a quote now standard in many pathology rooms around the world.

 

Sentinel species

“Marine animals are sentinel species,” she said. “They are long-lived in the ocean environment. We can sample them for environmental contaminant monitoring. Their bodies can reveal pathogens, ecosystem shifts. They are Silent Teachers.”

 

Marine mammals often strand when they are too sick or wounded to carry on in the ocean. The samples CCMART takes from dead animals, or the necropsy on an entire carcass, comparable to a human autopsy, may reveal not only why it died, but additional information about its life and the ocean conditions in which it lived.

Barbie Halaska, executive director and senior scientist at CCMART, measures the carcass of a California sea lion, one of the steps in data collection on stranded marine mammals. (CCMART photo)

 

Halaska and her team have examined 175 dead marine animals this year. She can’t say whether that’s a normal number, since this is the first year she’s keeping track of what’s happening along our shoreline.

 

Most California sea lions are born in June, but Halaska started seeing pups born dead or prematurely in May. The deaths may have been a result of the mother seals being sickened by domoic acid, a naturally-occurring toxin in one algae species. The seals eat the fish that eat the algae, and the toxin bioaccumulates in their bodies. The Marine Mammal Center rescued at least 13 between March and May.

 

Halaska collected a dead mature Guadalupe fur seal female, which she put in the freezer and will necropsy later. The seal weighs 85-90 lbs, and may have been pregnant.

 

“We don’t see a lot of strandings of older, mature Guadalupe fur seals,” she said.

 

Gray whales have stranded in higher numbers this year, 146 reported so far, compared to average annual numbers of 43 from 2006-2023. None have stranded on the Central Coast, found instead north of here, in San Francisco, Oregon and Washington. The deaths probably reflect changing ocean conditions that reduce the amount or quality of their prey, tiny amphipods that live in sediment on the ocean floor.

 

Usually, Halaska necropsies (like an autopsy, only with animals) the critters on the beach where they land, takes samples, and leaves the rest, covered with sand, behind.

 

“Scavengers can pull apart a carcass in a day and a half, if there’s no people around to scare them off,” she said. “The gulls appreciate it.”

 

Testing samples

Whale and seal blubber hold persistent organic pollutants, such as PCBs and PFAS (forever chemicals), and microplastics. Ear wax builds up in whales to form a lifelong plug that can be investigated to reveal events in the whale’s life history, such as hormonal changes that reflect pregnancies.

Dead marine mammals can be indicators for public health, especially sea lions that are affected by domoic acid which can be concentrated in filter feeders such as mussels, clams, and other shellfish and affect humans.

Whale baleen and seal whiskers, formally called vibrissae, can also show an extensive record of environmental contamination or even what the animals were eating before they died.

Other findings can add to knowledge of anatomy, their natural history, and the health of the population, as well as environmental contamination.

CCMART has the required special permits from State Parks and NOAA to go onto the beach to take samples from dead animals. They report every time they go onto the beach for a dead animal.

CCMART volunteers begin work to take measurements from a Risso's Dolphin that washed up dead on a Central Coast beach. (CCMART photo)

 

Nonprofit organization

CCMART is a dedicated first responder for deceased marine mammals and sea turtles in San Luis Obispo & Santa Barbara Counties. The organization is part of the National Oceanic and Atmospheric Administration’s Marine MammalHealth and Stranding Network.  The University of California at Davis handled H5N1 testing, declaring the outbreak over on March 24. 

Twenty volunteers are now trained to respond to reports of dead animals on the beach. They assess the carcass, determine the species, and measure the remains.

 

Halaska plans to hold another volunteer training session in October. All skills are welcome. CCMART is funded by grants and donations.

 

Photos such as this one, of a dead Risso's Dolphin, help guide CCMART volunteers and staff to marine mammal carcasses for evaluation. (CCMART photo)

If you find a dead animal:

 

Anyone can report dead marine mammals to CCMART, by phone, through the website, or via email 

info@ccmarineresponse.org.

Stranding Hotline: 805-242-3560

Stay back at least 150 feet. The possibility of human infection is very low, but dogs might catch something. Keep the dog on a leash.

Photos help. Try to determine the position of the dead animal in relation to the high tide line.

 

Drop a pin or include the coordinates with the report.

Having a time and location stamp on your photo app helps.

Christine Heinrichs is the Monterey Bay National Marine Sanctuary Advisory Council SLO At-Large member. Follow her on Facebook, Bluesky, LinkedIn, and Substack.

Return of the Bulls

And the living is easy.

Lots of females and young seals remain on the beach, but a few young bulls have shown up. The older bulls will follow, and males will dominate the beach for the summer.

The bulls are returning to molt their skin, as the females and juveniles are finishing their molt. The process is the same: the old brown skin peels off, starting around the eyes and ears, old scars, and other body orifices. Then the belly and sides and back peel off.

This female has several cookie cutter shark scars that started her molt. Cookie cutter sharks are small sharks, 18 inches or so, that bite into the blubber, twirl around to take a plug, and leave behind that distinctive circular scar. A good blubber meal, but not a threat to the seal. (Christine Heinrichs photo)

It takes an average of 32 days.  Seals arrive and leave on their own, individual schedules, so they are always arriving and leaving.

The new skin and hair underneath is gray. The hairs are short, but soon stand up and grow longer. Look for pearly gray seals next to brown and tan seals.

This seal shows a big shark scar. She lived to tell the tale! (Christine Heinrichs photo)

Leaving to migrate north

Juveniles and females leave the beach for their foraging grounds, along the continental shelf and out in the open ocean. The juveniles will return in the fall, for six weeks or so of rest. The females are on their long migration. They will have around eight months to put on weight and gestate a pup. They will return in January, when they come back to give birth.

The bulls aren’t at their highest weight, but they are in good condition. Young bulls, five to six years old, not yet in the breeding population, may spar with each other. Older bulls, not so much. Their sex organs shrink and they stop producing sperm and sex hormones during the summer.  The beach is quieter than during the winter breeding season. They’ll all leave the beach by late September, giving them three or four months to bulk up before returning in November and December for the breeding season.

Visitors enjoy seeing the big males. Their size, over two tons, and more than fifteen feet long, is always awe-inspiring. Their floppy noses and pink chest shields are a sight to remember when they get home.

Each rookery is identified by a different flipper tag color, connecting the seal with the beach where it was born. 

Cal Poly tagged seals

Katie Saenger, Cal Poly master’s degree student, defended her thesis to an appreciative audience at Cal Poly’s Fisher Hall in San Luis Obispo. What great weaners she tracked! Each one took a different route — in some cases, more than one migration.

Officially titled “Movement of weaned northern elephant seal pups during their first at-sea foraging migration,” she put tracking devices on a total of 25 pups over three years, 2022-2024.

See their tracks here for the first five in 2022; here for the ten in 2023; and here for 2024. Vandenberg Space Force Base paid for the study, so the first five seals were tagged there and named for Vandenberg launches. The next ten, five tagged at Vandenberg and five at San Nicolas Island, got names of local animals and plants. The third year had an astronomical theme, which included one named for Neil deGrasse Tyson.

Although most of the seals congregated in the Central Coast area, Monarch went all the way to the Aleutians and back on her first migration. I’ve written about her amazing journey. Unfortunately, since the battery on her device died, her data was not included in the data analysis, since it counts as an Incomplete Trip.

Not to say it is insignificant! What a champ.

Aurora actually turned south, on her second migration. She was one of the seals who left on her first migration, then hauled out on the beach, and then left again. This behavior was not previously identified, so Katie and the tracking devices revealed that weaners may take two or, in one case, a third migration.

The seals swim back to places where they found plenty of fish to forage on. They are learning about their ocean home, and how to survive in it.

Fox circled the Channel Islands. Frog spent some time in San Francisco Bay.

All these seals now have flipper tags to identify them in future, blue for Vandenberg and red for San Nicolas. Other colors signify other rookery locations.

I’d love to know what becomes of Monarch. Will she become a Supermom? Will Aurora explore Mexico and focus her beach life there? What’s in store for Seal deGrasse Tyson?

Katie said that following these seals through their lives is her Dream Study. Because the seals molt their skin every year, there’s no way to mark them permanently, except for the small blue flipper tags, or place permanent tracking devices on them.

TMMC releases rehabbed elephant seal pups

The Marine Mammal Center, https://www.marinemammalcenter.org/, recently released two rehabbed elephant seal pups at Leffingwell Landing in Cambria, Rocky and Carnation. As seals that have been rescued and rehabilitated, they have orange flipper tags.

Rocky and Carnation leave their carriers. They wear hat tags, 3D printed tags made of compostable/biodegradable material. The tags will soon fall off in the ocean. The pups wear them as patients so that caregivers can identify which animal is which in a pool of bobbing seal heads. Each seal has an individual medication and treatment plan. (TMMC photo Laurie Miller)

The event emphasized TMMC’s work to interconnect marine mammal care, humans, animal populations and the ocean. The problems of individual marine patients draw a direct line to global marine health and human wellbeing.

“Our work is aligned with One Health, a collaborative approach to global wellbeing that recognizes the interconnections among people, animals, plants and their shared environment,” the center said in a prepared statement.

Inviting the public to see rehabilitated seal patients released back to the ocean advances the center’s mission by engaging public support and encouraging donations.

“Threats to our ocean cannot be addressed by simply rescuing more animals. We cannot return healthy animals to a sick ocean and expect them to thrive,” the statement said.

Federal funding to support marine mammal research has been cut. Proposed legal changes, such as to the Marine Mammal Protection Act, would reduce protection and the government’s ability to defend marine mammals. The deep-water ocean monitoring system that has provided information about ocean health, climate, fisheries, and coastal flooding for ten years is being dismantled.

The center seeks support to “strengthen its capacity as marine mammal first responders, train more wildlife health professionals from around the world, and engage more children and adults as ocean stewards.”

Rocky and Carnation take different paths

Sea lions always rush for the surf. Elephant seals, not so much. Carnation took his time, but once a wave splashed over him, he was off.

Carnation is ready to go. (TMMC photo Laurie Miller) 

Rocky wasn’t ready to go. He held back, stayed on the beach, even turned around once.

Rocky is reluctant to leave. (TMMC photo Laurie Miller) 

Waves washed over him, rolling him around. He didn’t seem to like that. Once in the water, he would swim free, but at the surfline, he was rolled, again. He headed for his namesake, the rocks.

Eventually, TMMC volunteers recaptured him in an animal carrier. They put him in the van and brought him to a more isolated beach, where he returned to the ocean.

Would he rejoin his companion? Would either of them care? Elephant seals are solitary when they are out at sea. What do elephant seals think?

The seals get to keep those secrets, for now. But I’m looking for those flipper tags…

Weaned pups face the world

 Swim School to prepare for migration

This season’s Piedras Blancas elephant seal pups are now independent seals. Their mothers weaned them, abruptly, and left on their short spring migration. It’s on the pups now to develop the swimming and diving skills to make it on their own.

A complication this year is the threat of H5N1, Highly Pathogenic Avian Influenza, that hangs over them. The outbreak has been confined to San Mateo County, but on Thursday March 26, test results confirmed that a young sea lion in San Luis Obispo County had died from it earlier in March. A network of marine observers continues to monitor for other cases.

Swim School

At the Piedras Blancas viewpoint, weaners spread out across the beaches. They may collect in groups, called pods. Weaner pups are easy to recognize. They are fat, even roly-poly. They gained weight fast in the month they spent nursing, from 75 pounds to 300 pounds. Since then, they have had nothing to eat, until they get out into the ocean and start hunting fish and squid.

A wave splashes a juvenile elephant seal near the Piedras Blancas Lighthouse on March 3, 2026. David Middlecamp dmiddlecamp@thetribunenews.com

They were born all black, but they shed that black coat in their first molt when they were weaned. Now they are countershaded, light on the belly and dark on the back. Many marine animals have that color pattern, helping camouflage them from their predators.

Look for them splashing in the waves, practicing holding their breath and learning to swim and dive. They may take refuge from the heat in the cool ocean water.

Pups aren’t born with much ability to swim, so this transition time is when they go from beach to ocean. Weaned pups learn to hold their breath for around six minutes, some as long as 12 minutes. That will help them stay underwater and dive deep enough to catch food. They are on their own now.

Most will leave the beach on their first migration by the end of April.

Watch a video on the Friends of the Elephant Seals YouTubechannel.

Nearly all the elephant seals on the beach at Piedras Blancas are this season’s pups, now preparing for their first migration. Christine Heinrichs

Stranded weaners

One result of the H5N1 outbreak is that The Marine Mammal Center is temporarily not responding to reports of stranded weaners. Some weanlings that start their first migration can’t quite make it in the ocean. They wash up on local beaches, underweight and exhausted.

They may be camouflaged among driftwood and rocks, or unprotected on the sand. Most frequent locations for stranded weaners include Morro Bay, Avila Beach, Oceano, Pismo Beach, and San Simeon Cove.

The Marine Mammal Center is taking reports of stranded weaners, but because they don’t want to risk bringing this contagious virus back to their hospital, they will not send responders to evaluate or rescue the seal.

If you see a stranded weanling seal on the beach, stay clear of it. Risk to humans is low, but not non-existent, and the virus could be transmitted to pets at home. Call for help, The Marine Mammal Center 24-hour hotline, 415-289-7325 (SEAL). Take photos. Find out what the location is. Find beach staff members of other agencies and ask for advice.

Report dead seals and other marine mammals to the West CoastMarine Mammal Stranding Network.  Anyone who finds a dead, injured, or stranded marine mammal along the West Coast can report it at 1-866-767-6114.

“Keep your distance. Keep yourself and your animals safe,” Moe Flannery, senior collection manager for the California Academy of Sciences, said. Her team responds to reports of dead animals from the public by going out to the beach, recording the details about the animal, taking samples and specimens for testing.

“Report them and we will approach them safely,” she said.

TMMC watches over more than 600 miles of coastline, from San Luis Obispo County to Fort Bragg in Mendocino. For this outbreak, the focus is on San Mateo County, north and south of Año Nuevo. 

UC Santa Cruz researcher in Hazmat suit examining elephant seal pup, Ano Nuevo State Park, California. Frans Lanting Beltran Lab / UC Santa Cruz

The H5N1 outbreak

The outbreak of H5N1, Highly Pathogenic Avian Influenza, among elephant seals on California’s coast in February has claimed at least one sea lion and one southern sea otter in San Mateo County as well. The spread to two other species concerns scientists studying the outbreak, but the slow progression suggests that the outbreak is not spreading.

“We haven’t heard of any other colonies experiencing symptoms,” said Patrick Robinson, director of the Año Nuevo Reserve, where elephant seals have been studied since the 1960s.

“It’s not unusual that N5N1 spreads to other species,” said Christine Johnson, director of the NSF Center for Pandemic Insights at UC Davis. “We see occasional one-offs in other species. We’re going to hope it stays that way for sea otters.”

Of the 47 seals at Año Nuevo that have died since the outbreak began, some may have died of natural causes. Most of the seals that have died are weaned pups. A few large males have also died.

“That makes the mortality on the beach four times higher than last year,” Dr. Robinson said. “But it’s not as bad as has been seen in other areas.”

When H5N1 appeared in South American elephant seal herds in 2023, it killed more than 95 percent of the pups born in that breeding season. Researchers are studying the long-term effects of those losses on thepopulation. 

Dr. Robinson first identified the sick and dead seals. His account of finding them is chilling, in this interview at the Seymour Marine Discovery Center.

A pup and adult elephant seal have a conversation near the Piedras Blancas Lighthouse on March 3, 2026. David Middlecamp dmiddlecamp@thetribunenews.com

Adult females already left

Elephant seals are migratory. When the H5N1 outbreak began in mid-February, around 80 percent of the females had already weaned their pups and left the beach on their short spring migration, so they likely escaped exposure to the virus. By March 11, Dr. Robinson saw only two adult females on the beach.

Roxanne Beltran, an assistant professor in ecology and evolutionary biology at UC Santa Cruz, and her team had placed tracking devices on seven females before they left. Beltran’s lab leads the university’s northern elephant seal research program at Año Nuevo. The tracked females are migrating normally in the north Pacific, which suggests they are not sick.

Follow the tagged adult female seals here.

Tourists stop to watch northern elephant seals near the Piedras Blancas Lighthouse on March 3, 2026. David Middlecamp dmiddlecamp@thetribunenews.com

From mild to deadly

A mild avian influenza virus has circulated for years, among migratory birds and poultry production facilities. Influenza viruses are constantly changing, and the avian influenza virus evolved into a highly pathogenic form in the 1990s. It first appeared in China, but spread across Asia, Africa, the Middle East and Europe in the 2000s. 

Humans are rarely affected, but H5N1 adapted to infect other wildlife and domestic species. In 2024, it went from birds to mammals, infecting dairy cows. Milk production dropped, causing dairy farm losses. California, which is the nation’s top milk-producing state, declared a state of emergency in December 2024.

Since then, globally, H5N1 has infected sea lions in Peru and Chile, elephant seals in Argentina, and foxes in Canada, France, and other countries. Wild or feral animals such as foxes, bears, and seals; stray or domestic animals such as cats and dogs; farm animals, such as goats, cows, and mink, and zoo animals such as tigers and leopards have been affected. Many seabird and other migratory bird species can carry the infection.

H5N1 losses threaten wildlife that are already listed as endangered species. As of December 2025, H5N1 had infected some 598 types of bird and 102 mammal species, according to the United Nations, a substantial increase in just 18 months. In August 2024, the U.N. reported 485 bird and 48 mammal species.

An outbreak in imperiled species, such as endangered condors, threatened southern sea otters, and endangered Hawaiian monk seals, could push them to extinction. In 2025, TMMC conducted an experiment using a reformulated cow H5N1 vaccine from Zoetis, a veterinary pharmaceutical company, on California’s elephant seals, to determine whether it might be effective in immunizing endangered Hawaiian monk seals, with a precarious population of 1,600. Results showed some antibody production, and the vaccine has since been used on three monk seal pups at the Marine Mammal Center’s Hawaii location, Ke Kai Ola, the dedicated Hawaiian monk seal hospital in Kona.

Wildlife is already fighting to survive against a changing climate, disappearing habitat, and other stressors.

Veterinary experts at The Marine Mammal Center’s hospital and visitor center in Sausalito, California, carefully place a post-release tracking tag on the head of a northern elephant seal pup as part of an Avian Influenza vaccine trial on Aug. 27, 2025. Bill Hunnewell The Marine Mammal Center

How it started

This outbreak probably started with pups coming in contact with infected bird feces on the beach, as they roll around in the sand.

 “What we think is this is most likely a new introduction of what has been a very well-known and common genotype that has been documented since 2022,” Dr. Johnson said.

“It looks like bird-to-seal rather than seal-to-seal transmission,” said Dominic Travis, Chief Programs Officer at The Marine Mammal Center.

Dr. Johnson’s team has tested samples from seals as far north as Humboldt, which show no signs of H5N1.

The Marine Mammal Center’s Dr. Dane Whitaker, left, associate veterinarian, and Sarah Pattison, director of hospital operations, collect a blood sample from a northern elephant seal patient during an Avian Influenza vaccine trial at the Center’s Sausalito-based hospital on July 14, 2025. Bill Hunnewell The Marine Mammal Center

Transmission routes

During the Southern elephant seals outbreak, seals were able to catch it from each other. Seal-to-seal transmission made the virus more dangerous. That doesn’t appear to be happening in California.

“We don’t know any of that yet,” said Dr. Johnson, whose team is collaborating with UCSC to evaluate the Año Nuevo cluster. They are matching patterns of the quickly mutating virus as it evolves over time. “It’s a unique opportunity in wildlife,” she said.

The long-term monitoring of the Año Nuevo elephant seals provides advantages, such as knowing which mother gave birth to which pup. One mother, her skin marked with bleach 007, showed symptoms, but later recovered and appeared well. Her test results have not been completed yet.

Whether elephant seals can be immune is “a million-dollar question,” Dr. Johnson said. Looking back ten years may provide insight into whether seals have been exposed to less pathogenic influenza that have given them some immunity. 

“This whole outbreak has really brought together an amazing diversity of people that has shown me how many people care about these animals and the Central Coast,” Dr. Robinson said. “That just makes me really happy to learn that that many people care about this area, and that it's one of the many reasons why long-term monitoring is really important.” He concluded with “I'm going to make a plug for continuing science funding in general.”

Human risk

H5N1’s threat to humans is rated Low. The public can protect themselves further by avoiding contact with sick or dead animals. Keep pets on a leash on the beach. Do not let them approach wild animals.

“The risk is low to the general public, but higher with direct contact,” said Catherine Sallenave, infectious diseases staff physician for San Mateo County.

An adult female elephant seal throws sand on her back near the Piedras Blancas Lighthouse on March 3, 3036. The females are leaving behind weaned pups who will learn to swim in the near-shore waters. David Middlecamp dmiddlecamp@thetribunenews.com

Most seals are fine

The State Parks tours were closed in February, before the usual March 31 conclusion, at the end of the breeding season. Ticket sales will reopen October 20 for tours beginning December 15. Other elephant seal viewing sites remain open, at Piedras Blancas-San Simeon and Point Reyes.

The Piedras Blancas viewpoint remains open, with no seals reported sick.

“Just to assure everyone, we see thousands of apparently healthy animals at Año Nuevo, and we’re only observing a small number of impacted animals every day,” Dr. Robinson said. He and his team find about two dead and two sick weanlings every day.

Stay informed

Updates are posted as they are available.

 

Christine Heinrichs is SLO At Large Member of the Monterey Bay National Marine Sanctuary Advisory Council. Her elephant seal column won first place from the National Society of Newspaper Columnists in 2024.

 

 

 

HPAI H5N1 found in California seals

California State Parks closes beach to visitors

Seven weaned elephant seal pups that looked sick on February 19 and 20 in California’s Año Nuevo State Park tested positive for highly pathogenic avian influenza (HPAI) H5N1, the U.S. Department of Agriculture’s National Veterinary Services Laboratory confirmed late Tuesday, February 24. Thirty seals have died, but test results have not yet confirmed that they died of H5N1

The outbreak marks the first cases of HPAI H5N1 in marine mammals in California and the first detection in northern elephant seals. 

“This is exceptionally rapid detection of an outbreak in free-ranging marine mammals,” said Professor Christine Johnson, director of the Institute for Pandemic Insights at the University of California, Davis’ Weill School of Veterinary Medicine. “We have most likely identified the very first cases here because of coordinated teams that have been on high alert with active surveillance for this disease for some time.” 

On Monday, February 23, California State Parks closed Año Nuevo State Park to public access for the elephant seal viewing area of the Año Nuevo Coast Natural Preserve. With the confirmation that H5N1 was responsible, the tours have been canceled for the rest of the season.  

State and federal agencies work together

UC Davis scientists have been testing samples from marine birds and mammals at the park and other regions along the coast since 2024. The NSF Center for Pandemic Insights at UC Davis and UC Santa Cruz have been working together to increase surveillance at this site over the past two months in anticipation of a possible outbreak in seals.

The scientific team is now working closely with NOAA Fisheries, the California Department of Fish and Wildlife and the West Coast Marine Mammal Stranding Network to continue to monitor marine mammals along the coast.

On Feb. 19 and 20, Beltran’s team noticed seals at Año Nuevo Reserve with abnormal respiratory and neurological signs, including weakness and tremors. The Reserve’s elephant seals are intensively studied, with 380,000 observations collected over the years. One of the dead weaners was the pup of a marked mother who was herself born on that beach. The pup was entered into the research program when she was 15 days old. She was weaned when her mother left the beach, and two days later the team observed her convulsing on the beach at 9:30 am. By afternoon, she was dead.

“It’s tough to watch animals we have followed and watched for years get sick,” Beltran said. “We know their family lineages." She praised her team’s professionalism in continuing to collect information.

That individual information will help to assess the long-term effects of how many pups survive, whether females are affected, and future births, on the population.

They collected samples from sick and dead elephant seals and took them to UC Davis for testing at the California Animal Health and Food Safety Laboratory System. Initial screening revealed the samples were positive for avian influenza, which the USDA’s NVSL lab now confirms is HPAI H5N1.

“Given the catastrophic impacts observed in related species, we were concerned about the possibility of the virus infecting northern elephant seals for the first time, so we ramped up monitoring to detect any early signs of abnormalities,” said Roxanne Beltran, a professor in Ecology and Evolutionary Biology at UC Santa Cruz. Beltran’s lab leads UC Santa Cruz’s northern elephant seal research program at Año Nuevo.

“We are cautiously optimistic, as most of the adult females had already departed the beach for their routine migrations before the outbreak began, and most seals on the colony seem healthy,” Beltran said. 

Virus threatens wildlife worldwide

As reported by Sharon Guynup in Mongabay in 2024, H5N1 is a highly contagious, deadly strain of avian influenza. It evolved from a mild form of avian influenza in the 1990s into a deadly pathogen from infected industrial poultry operations, breaking out in Europe in 2020.

Since then, it has leapt the species barrier, affecting at least 485 bird species and 50 mammal species, killing seals, sea otters, dolphins, foxes, California condors, albatrosses, bald eagles, cougars, polar bears and a zoo tiger. Animals as diverse as rats, elephant seals, bears, house cats, and humans — with an unprecedented outbreak in U.S.dairy cattle having affected 17 states and more than 1,000 herds. 

It is carried by migratory birds, and has been found on every continent except Australia, including Antarctica. In some bird and mammal species, the toll has been devastating. Some imperiled species could be pushed to extinction, with wildlife already fighting to survive against a changing climate, disappearing habitat and other stressors.

Since 2024, 71 human cases have been diagnosed in the U.S., with two deaths. Current public health risk is rated Low, with no person-to-person transmission reported.

“The more a virus like this is able to mutate and find its way into a wide range of species, especially farmed species that live in close contact with people like poultry and now cattle, the more the odds go up that a viral strain will more easily make that leap to people,” wildlife veterinarian Steve Osofsky, D.V.M., the Jay Hyman professor of wildlife health and health policy at Cornell University’s College of Veterinary Medicine, wrote in Stat in June 2025.

Rapid transmission

The virus’ ability to change rapidly, and its record of infecting other species makes it a cause of intense concern. 

Pinnipeds such as elephant seals, which congregate in large groups, are among the vulnerable species. The virus swept along South America’s Atlantic and Pacific coastlines, slaying more than 30,000 sea lions in 2022-23, when the H5N1 virus moved down from North and Central America to invade both the Atlantic and Pacific coasts of South America. In 2023, it killed an estimated 17,000 Southern elephant seal pups  (Mirounga leonina) on Argentina’s Península Valdés — the species’ largest die-off ever.

No more tours this season

At Año Nuevo, a California State Parks spokesperson said that 134 tours totaling 1,203 tickets were canceled through March 1, including 22 school tours. Thousands ofvisitors pay $11 per person to hike out a mile and a half to two miles with a guide to view the elephant seals during the mid-December through March pupping and mating season.

The park’s Mainland Camera remains active to watch the seals on the beach.

#añonuevo #CaliforniaStateParks #sanmateocoaststateparks #ThatsMyPark

The Marine Mammal Center has suspended its rescue response to elephant seals and harbor seals, until further information indicates whether this is an isolated cluster or the beginning of a wider outbreak.

“If it’s a cluster, we will figure out,” Dominic Travis, Chief Programs Officer, The Marine Mammal Center, said. “If it’s perpetuated, it will be really tricky. We will assess it day by day with NOAA.”

 

Most of the adult seals have left the beach on their next migration, escaping from what may be only a cluster of infection. As of February 25, only a small number of seals have been affected.

Traveling with an elephant seal bull

 J912’s tracking device reveals his journey

An adult male elephant seal, marked J912, with a tracking device on his head and an antenna on his back, hauled out February 5 at Piedras Blancas.

J912 ar Piedras Blancas. David Lawrence. 

Friends of the Elephant Seal docent Barrett Stuart was the first to notice that the seal, among many other males on the beach, had a device on his head. In February, breeding season, male seals are on the beach, moving around, seeking advantage with females and threatening each other.  He reported the sighting. FES docents Rian Dom and Dave Lawrence decided to revise their plans for the following day and go look for him.

 “Rian and I were going to tag hunt at VP2, but she suggested we start at VP3 to try to photo this seal,” Lawrence said.  “Rian is responsible for getting me there that following morning. I’m glad we did!”

VP2 is the elephant seal site south of the main viewpoint. “Tag hunting” is looking for seals with flipper tags, to photograph and report to researchers. Resighting tagged seals is important, to document where seals go and when.

Elephant seal J912’s tracking device, glued to mesh that is glued to the seal’s head. Dave Lawrence

Tracking male seals

It’s unusual, and exciting, to see any seal with a tracking device at the viewpoint. It’s always a female. Males are hardly ever tracked.

They, like much wildlife, migrate across international boundaries, making protection complicated. Hoary bats have flown from California to Hawaii. In January, a waved albatross, a critically endangered species from the Galapagos Islands and South America, was seen off Cambria’s coast. The bird had traveled about 3,300 miles from its typical range, making it an avian “vagrant,” the term used for birds outside their usual range.

Wide-ranging wildlife requires a global perspective. In J912’s case, it led to international cooperation to test a tracking device.

Dan Costa, Distinguished Professor of Ecology and Evolutionary Biology at UCSC, and head of the Costa Lab, said “J912 is a male that we tagged at Ano Nuevo last summer-fall after he molted. He is carrying two tags. One of the tags is a device we were testing from King Abdul University of Science and Technology, or KAUST. KAUST is in Jeddah, Saudi Arabia, and has an excellent technology development team. The device had GPS tracking capability and recorded dive behavior, and it used the Iridium Satellite system to transmit data. The other tag is one of our more standard tags built by Wildlife Computers in Redmond, Washington. It recorded diving behavior and animal position; position data were transmitted via the ARGOS satellite system.”

The KAUST tag has a much higher data bandwidth than the standard Argos tags, but is more challenging to establish communications with, especially on diving animals. It transmits GPS locations and has an accelerometer for measuring fine-scale head movement. Those head movements can be interpreted as feeding, when the seal catches prey.

The standard tag collects basic oceanographic data, depth, and temperature, the standard set of measurements for understanding the ocean environment.

“The rationale for the study is to learn more about male elephant seals.,” Dr. Costa said. “We have over 1000 records from individual female elephant seals, but only a few tracks of males (fewer than 50). Males are less reliable than females; that is, they aren’t as likely to return to Año Nuevo, as this individual shows, so there is a greater chance of not recovering the tag and thus not retrieving as much data.”

During the summer, J912 was on the beach to molt his skin. The device was attached after he had molted, to the new skin that would last for a year. He then left to go feed along the continental shelf, gaining blubber to sustain him though the breeding season.

 

In J912’s case, the tracking record shows that he left Año Nuevo on August 30 and arrived in the Aleutian Island foraging site, 2,573 miles away, on October 11, a 42-day migration, averaging 61 miles/day.

At the urge of some unknown signal, after feeding for two months, on December 4 he turned around to return to California from the Aleutians. He arrived on land near Point Buchon, 2,718 miles, on January 17, a 51-day migration, averaging 53 miles per day.

 

In both directions, he travelled in more or less a straight line. He stopped in places, perhaps to eat along the way, but his main goals were the rich foraging grounds in the Aleutians and then to return to California.

 

J912’s tracking records show that he had been around Piedras Blancas for a few weeks, before hauling out on the beach at Piedras Blancas February 5. He visited at least four birthing beaches in the rookery, but it isn’t clear whether he stayed to breed.

He was seen at Año Nuevo a few days earlier, but he was in the water then, and the team couldn’t get to him. “Apparently he stayed in the water and swam south as fast as he could!” FES member Kathy Curtis posted on GroupMe.

I didn’t see J912 while he was at Piedras Blancas. He stayed only two days, then moved on north to the Lighthouse Beach on February 8. He may find a breeding beach where he stays for a while, or move on. The device will record where he goes, and for how long.

The team may leave the device on him until he returns to Año Nuevo to molt, in July. The data from that, and the other four seals’ devices, will add to the understanding of these seals’ lives.

“Our goal is to better understand large male foraging behavior and ecology, energy gain rates, and diving physiology,” another member of J912’s research team said. “The other four males all returned to Año and we were able to recover all of their tags over the last month, which is really exciting.”

The complex tracking equipment on elephant seal JP12’s head allows researchers to collect data on the ocean environment as well as the seal’s dives and migration. Dave Lawrence

Webinar on elephant seals

Dr. Roxanne Beltran and research technician Conner Hale of the Beltran Lab at UC Santa Cruz will discuss how tracking individual variations can contribute to understanding the species in a free webinar "Unraveling individual and environmental drivers of variation among elephant seals," Tuesday, February 24, 7 pm. Register here.

American Cetacean Society - San Francisco Bay Chapter — Dr. Roxanne Beltran, "Unraveling individual and environmental drivers of variation among elephant seals"

Christine Heinrichs is the Monterey Bay National Marine Sanctuary Advisory Council SLO At-Large member. Her elephant seal column won first place from the National Society of Newspaper Columnists in 2024. Follow her on Facebook, Bluesky, LinkedIn, and Substack.