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.