Some researchers in northern California found alarming numbers of dead baby sea lions on their California island breeding grounds. But scientists don’t yet know what caused their deaths – and whether these incidents are a sign of a larger problem.
The Los Angeles Times recently reported sightings of hundreds of what appear to be premature, stillborn or malnourished pup births on islands north of Monterey Bay. Other animal experts noted similar tragedies in the Channel Islands and Mexico, where sea lions gather en masse each year.
Luckily, local marine mammal experts haven’t noticed the same trend hitting San Diego – yet.
Eric Otjen, vice president of zoological operations at SeaWorld San Diego, said Thursday they’ve only had two reported stillborn sea lions in La Jolla Cove, California’s only mainland sea lion breeding ground. That’s not an abnormal number for this early in the pupping season. But SeaWorld’s partner facilities in Orange County have been calling for help with the larger amounts of young deaths experienced further north, he said.
It’s normal in nature that 10 to 20 percent of sea lion pups won’t make it through their youth, animal experts said. NOAA, which manages a sick or injured animal response network, said it’s monitoring the situation but overall the California sea lion population is healthy at 250,000 strong.
“We won’t know if the number of premature births exceeds the typical range until research teams complete their regular annual surveys of sea lion rookeries in the Channel Islands and other areas in the coming weeks,” wrote Michael Milstein, a NOAA spokesman in an email. “So far this year, there are no signs of widespread disease (including domoic acid) or other factors affecting the sea lion population as a whole.”
June is pupping season for California sea lions. Each year, the animals return to their breeding grounds, usually on offshore islands from central California to central Mexico, to give birth, according to the National Oceanic and Atmospheric Administration.
On some of the cases in northern California, scientists tested for bird flu, which has been spreading across the globe in recent years. In January 2023, the country of Chile experienced mass sea lion strandings and deaths linked to bird flu.
They’re also testing to see whether a red tide (an algal bloom in the ocean) turned toxic and affected certain sea lion populations. Domoic acid production in toxic red tides can accumulate in the tissues of shellfish and fish. When bigger animals eat that prey, like sea lions or even humans, the toxin can affect the brain, causing seizures and death. That’s exactly what happened in 2015 when the entire U.S. western coast experienced a massive die off of sea lions and other animals from central California to the Alaskan peninsula.
El Niño could also be to blame. During this climatic phenomenon which can last for several years, the eastern Pacific ocean warms up, and that generally means there’s less fish or prey. That means sea lion mothers have to swim farther and search longer. Since many of the pups were malnourished, researchers think the deaths could have been caused by a lack of food.
The National Geographic Magazine did a similar story, citing “Scients are sounding the read alarm” regarding the sea lions death and that article said it was due to a parasite infection…also saying “if the sea lions have them, then the humans do too.” So why are we scratching our heads about this? Too close to an election to tell the truth? Hummmm…?
Marine Biologists with a phd need to form an underwater neonatal intensive care unit! And I’m willing to bet that once they do the numbers that the amount of deaths is larger than usual ! Im also wondering if possibly a chemical found in that red stuff that most likely many mothers were exposed to caused pre-term labor and the ensuing pre mature births. I pray the food supply is replenished and bountiful for all mammals and other wild life. If that doesn’t happen it could be a precursor for other beings food supply… . We have to respect mother Earth and all her creatures.