From CO to CA: DZCA Experts Support Marine Mammals in Crisis

Earlier this spring, a deadly ecological crisis unfolded off the coast of Southern California. A harmful algae bloom—fueled by warming ocean temperatures and nutrient runoff—stretched across hundreds of miles of coastline. What made this event especially devastating wasn’t just its scale or duration, but the combination of domoic acid toxins released by Pseudo-nitzschia algae, and an unusual spike in saxitoxin. Together, these toxins triggered neurological symptoms in hundreds of marine mammals including confusion, seizures, aggression, and even death.

The Marine Mammal Care Center (MMCC) in San Pedro, California, was one of the first facilities to raise alarms about the looming crisis. As early as January, their team began noticing an uptick in sea lions displaying signs of domoic acid toxicosis. By mid-March, MMCC had treated more than 140 sea lions—and the numbers were rising fast. Despite efforts to notify city and county officials, few emergency resources were mobilized in time to meet the overwhelming demand.

Faced with one of the worst “harmful algal bloom” events on record, the center put out an urgent call to animal care professionals across the country.

Denver Zoo Conservation Alliance answered.

Over the course of the last month, ten DZCA staff members—including Animal Care Specialists, Registered Veterinary Technicians, Clinical Veterinarians, and our Veterinary Pathologist—traveled to San Pedro to support MMCC’s round-the-clock rescue and rehabilitation efforts. Working in tandem with MMCC’s local team, they helped care for over a hundred marine mammals, all suffering from the devastating effects of domoic acid exposure.

A Day in The Life at MMCC

Each day at MMCC begins early and runs long. Animal care teams start by preparing hundreds of pounds of herring—some to be served whole, some blended into a gruel (fish smoothie) for sick or young animals unable to feed on their own. Each sea lion or seal receives personalized feeding plans, vitamins, and medication, which must be monitored closely throughout the day. Between meals, care teams are cleaning enclosures, doing laundry, and assisting with animal transport, husbandry, and treatment—all while preparing healthy animals for release back into the wild.

Meanwhile, our Veterinary Medicine team staff provided essential diagnostics and documentation. Animals arriving at MMCC receive exams, bloodwork, and imaging. While some animals recover quickly, others require intensive, hands-on care for weeks to months. Sadly, not all survive.

But even in loss, there is purpose. Pathologists, including DZCA’s Dr. Sushan Han, perform necropsies that not only provide answers but also build a scientific foundation for future marine mammal care. Tissue samples are banked for toxicology and RNA research, revealing how this year’s dual-algae bloom is affecting animals in ways not previously seen. These findings are already being shared with regulatory agencies and coastal conservation networks to help shape long-term response strategies.

Hopeful News for Marine Mammals

As of late May, MMCC staff reported no new marine mammals showing signs of domoic acid poisoning, and the harmful algal bloom had cleared from local waters. Although this was the longest, most toxic, and deadliest bloom MMCC has ever experienced, they were able to overcome the crisis and give hundreds of marine mammals a second chance at life. This was largely possible thanks to public support, advocacy, and collaboration from wildlife experts nationwide.

“This year’s domoic acid event was the most severe we’ve faced, overwhelming our team with sick and stranded sea lions in need of urgent care. Responding to a crisis like this requires an extraordinary effort, and we’re incredibly grateful for the support of partners like Denver Zoo Conservation Alliance. Their generosity helped us provide lifesaving treatment and gave these animals the second chance they deserve,” said Dave Bader, MMCC Chief Operations and Education Officer.

This isn’t the first time DZCA has supported MMCC’s vital work. In 2023, we sent seven staff members to assist during a similar harmful algae bloom, providing critical hands-on care and expertise.

Dr. Jimmy Johnson, DZCA Senior Director of Wildlife Health & Conservation at DZCA, shared the following: “In our changing world, responding to situations that threaten wildlife is a community effort and we were happy to combine our wildlife care and health expertise with that of our colleagues at MMCC to help two years ago and again in 2025.”

Three DZCA Pinniped Care Specialists who work with reflected on their experience supporting MMCC:

“This is the second time that I was able to help at MMCC, the previous time being in 2023 during the last large DA event, and I am so grateful that I was able to go back and assist with animal care. Each time I have learned so much from the staff and volunteers who spent countless hours helping many seals and sea lions.

The highlight of my week was being part of releasing 15 healthy sea lions back to the ocean, as well as seeing one patient that hadn’t been eating starting to show interest in food and eat. It was a very humbling experience to see how much time and effort is put into these animals.

Now that sea lions are back at the Zoo, I hope we can really make the connection as to how special these animals are and that we can all do our part to help.”

Meryt Schumacher, DZCA Animal Care Specialist

“After working with non-releasable, rescued sea lions for years, it was incredible to get to put my skills to use to help save the sea lions who can be released back to the ocean. I love caring for the sea lions who don’t have the skills to survive on their own and being able to show our guests just how amazing this species is.

The goal is always to keep as many sea lions out in their natural habitat as possible and getting the chance to contribute to that goal will be an experience I will never forget.”

Leah Swift, DZCA Animal Care Specialist

“Having worked with our DZCA sea lions my entire zoo career, I have spent years speaking to guests about why sea lions often need to be rescued, how they can often be released, but sometimes, like in the case of Nick and Maverick, are deemed non-releasable and need to be rehomed. It is incredibly meaningful to now get to speak to my own time spent being a part of that process, both rescue and release, and to bring those experiences back here to Denver to share with our guests.”

Brandi Taylor, DZCA Animal Care Specialist

Back with a Splash: Sea Lions Return to DZCA

While part of our team supported sea lions on California’s shores, we were also preparing something special back home in Colorado. On June 20, DZCA proudly unveiled our brand-new California sea lion habitat, a vibrant and enriching space that reflects both the energy of the animals and our century-long commitment to their care.

This dynamic new habitat replaces the Zoo’s historic 1987 sea lion home with thoughtful upgrades for both animals and guests. A new saltwater, temperature-controlled pool system supports sea lion health, while behind-the-scenes areas give our Animal Care team more room to support enrichment, training, and social time. A colorful fishing village-inspired exterior echoes the coastal communities where wild sea lions live—and where our teams have been making a difference.

Visitors can now enjoy a 16-foot underwater viewing window for incredible glimpses of sea lion life below the surface, as well as daily training demonstrations that highlight each animal’s unique personality and the expert care they receive every day.

Maverick, one of four sea lions thriving in our new habitat, has a story closely tied to the work our staff supported at MMCC this year. Rescued as a malnourished pup during a 2015 stranding event, he was rehabilitated and released but stranded again after not being able to find enough food. Deemed non-releasable, Maverick found a permanent home at DZCA.

Now nearly a decade later, he’s a powerful ambassador for marine mammal rescue and rehabilitation—reflecting the journey of many animals affected by this year’s harmful algae bloom. Our new habitat allows guests to connect with sea lions like Maverick and see the impact of DZCA’s dedicated Animal Care and Health teams.

Saving Wildlife Together: Connecting Conservation and Care

Denver Zoo Conservation Alliance’s mission extends well beyond its 80-acre campus. Whether responding to whether responding to wildlife emergencies, driving conservation impact in the field, or elevating our habitats, care, and impact on campus, our team’s work is rooted in science, compassion, and action.

The story of this spring’s algae bloom—and the collaborative rescue efforts it inspired—reminds us that conservation doesn’t happen in isolation, and collaboration is key to helping save wildlife.