Poisoned sea lions are showing up on California beaches. Here’s why experts are worried
More than 20 California sea lions are suffering from deadly domoic acid poisoning on the West Coast, including a handful in San Luis Obispo County, according to the Marine Mammal Center in Sausalito.
Sickened marine mammals have been found in Avila Beach, Pismo State Beach and Oceano Dunes State Vehicular Recreation Area.
Domoic acid poisoning is caused by an algae, Pseudo-nitzchia australis, that produces a natural neurotoxin that accumulates in fish such as sardines and anchovies.
When a sea lion eat affected fish, the neurotoxin gets absorbed into their bloodstream, and “causes vomiting, unusual behaviors, seizures, loss of pregnancy and death” according to the National Oceanic and Atmospheric Administration’s National Centers for Coastal Ocean Science.
If left untreated, domoic acid poisoning can lead to permanent brain damage.
Typically, most cases of poisoning occur in July through August. This year, the cases started appearing earlier in the season in Mid-May.
“The early timing of this year’s outbreak is especially concerning because female sea lions could get sick on their way to the Channel Islands to give birth, putting their pup’s survival at serious risk,” Dr. Cara Field, medical director at the Marine Mammal Center, said in a June 17 news release.
Sea lions, marine mammals poisoned by toxic algae
Domoic acid poisoning is one of the foremost threats to marine animals — especially pregnant ones.
According to Dr. Shawn Johnson, vice president of veterinary medicine and science at the Marine Mammal Center, pregnant sea lions can’t clear the domoic acid poisoning out of their bodies as quickly as other sea lions.
Instead, the poison remains in the fetal fluid, recirculating in the body for weeks and constantly exposing the mother and unborn pup.
In some cases, the toxin can cause early termination of the pregnancy, Johnson said. Pups exposed to the poison early in utero are often stillborn.
The toxin can also affect the developmental health of young sea lion pups, causing epileptic seizures or death in their first few years.
Due to the coronavirus pandemic, the center has reduced personnel. Trained responders may not be able to rescue sea lions right away, the center said in a statement.
“The adult pregnant females are almost 200 pounds. They come up on our beaches, disoriented, and hurt. It takes a lot of effort and time and skill to help these animals,” Dr. Johnson said. “We are preparing our summer team with social distancing guidelines, but it will be more difficult for us this year.”
Recently, rising ocean temperatures have led to an increase in domoic acid posioning cases along the west coast — causing spikes to occur yearround, instead of seasonally.
As The Tribune reported in 2019, Southern California is considered a domoic acid hotspot, with toxic algal blooms worsening in California in the past 10 to 15 years.
The Marine Mammal Center identified the first cases of domoic acid poisoning in California sea lions because of a large outbreak in 1998. It has been studying the disease in sea lions and other marine mammals to develop treatment plans and save as many animals as possible.
Although the vast majority of the patients the center treats for domoic acid poisoning are California sea lions, other marine mammals are affected as well.
Domoic acid poisoning has been reported in other seal and sea lion species as well as blue and humpback whales. The center has also treated threatened and endangered species including Guadalupe fur seals and southern sea otters.
Johnson says the toxin is also filtered through shellfish, lobsters and crabs — primary food sources for endangered sea otters in California.
The Marine Mammal Center typically treats an average of 65 to 70 sea lions a year for domoic acid poisoning.
However, in 2019, the center responded to more than 100 sea lions with suspected domoic acid poisoning.
Forty of those cases occurred in San Luis Obispo County, including 31 cases during a large outbreak that July, according to an email from GianCarlo Rulli, marketing and communications associate at the center.
According to Johnson, typical treatments for domoic acid poisoning include anti-seizure medication and hydration. The toxin is excreted in the urine, and increasing fluids can allow the toxin to be excreted out of the body much quicker.
“There is no antidote to this toxin,” he said. “We are trying to prevent the critical signs and symptoms with medication with the hope that there won’t be severe damage to the heart or brain.”
If sea lions are able to recover, they can be released to the wild.
The Marine Mammal Center’s treatment protocol includes medications for the first week. After that, sea lions are weaned off them.
Once the sea lions start acting normal, they can be released three weeks after they’re brought to the center.
If the animals don’t get better without medication, they’re not healthy enough to be released back into the wild and have to be humanly euthanized. Johnson estimated that the center has been able to rescue and rehabilitate more than 40% of poisoned seal lions.
Humans at risk of domoic acid poisoning
People can also be affected by domoic acid poisoning when they eat tainted shellfish.
According to the California Department of Public Health website, symptoms of amnesic shellfish poisoning can occur within 30 minutes to 24 hours after eating toxic seafood, and can include vomiting, diarrhea, abdominal cramps, headache and dizziness. Mild symptoms typically go away within a few days.
In more severe cases, shellfish poisoning victims may experience trouble breathing, confusion and cardiovascular instability, as well as seizures, the permanent loss of short-term memory, coma or death, the agency said. However, these cases are rare due to the precautions taken by the department of public health.
When the state Department of Public Health receives a report of a possible domoic acid event, they consult with the center to determine whether there has been an increased number of strandings, and whether it is abnormal for that time of year.
The department then consults with the Department of Fish & Wildlife to determine whether the sea lions were exposed in the area of the stranding or in open water potentially miles off-shore. If the area is within three miles of the coast, local licensed fishermen are instructed to obtain crab, lobster, or fish samples to test for abundance levels of Pseudo-nitzschia australis.
If the sample exceed federal action levels, the department issues a health advisory and notifies Department of Fish & Wildlife and the California Office of Environmental Health Hazard Assessment for potential fishery closures.
What to do if you see a sick sea lion
If you see a sea lion twitching, staring up into the sky, rolling around or running around randomly, it’s a clear indication it needs medical assistance.
“A sea lion seen on the beach may be wandering around like it’s lost,” Johnson said. “Sometimes they can be aggressive because they are afraid. They don’t understand what’s happening.”
“It’s important to keep your distance, because they can be dangerous,” he said.
Johnson recommends staying 50 yards away from the affected sea lion, and taking video or photos of its behavior. This helps veterinarians assess the animal’s symptoms.
Vets can then prioritize which animals to rescue first and treat the mammals.
Members of the public can also be trained as response volunteers to help rescue animals. You can find more information on the center’s website at www.marinemammalcenter.org/Get-Involved/volunteer.
If you spot a marine mammal, and think it might need assistance, call the Marine Mammal Center’s 24-hour hotline at 415-289-SEAL (7325).
This story was originally published June 30, 2020 at 5:00 AM.