In just the first month this year, two Hawaiian monk seals have been killed or sickened by a disease that is released into the environment by cat feces.
The parasitic disease, known as toxoplasmosis, has led to the death of a juvenile male monk seal name Sole on the shores of Laie and caused a near fatal illness for a female seal known as Pohaku off Ko Olina.
Pohaku has so far survived longer than any other monk seal diagnosed with the disease and continues to improve under treatment.
Scientists from the National Oceanic and Atmospheric Administration provided these updates today while emphasizing the need to address the problem at its source.
“Really, where this problem needs to be treated is at its source, which is cats in the landscape,” said Angela Amlin, NOAA Hawaiian monk seal recovery coordinator. “A very simple thing that folks can do is if you have cats, keep them indoors. If they’re not on the landscape, then they’re not able to shed this parasite into the environment where it can infect people and other native wildlife including Hawaiian monk seals.”
As for feral cats, a meaningful discussion, along with a combination of legislation and public outreach are needed, said Amlin, as well as a comprehensive plan.
NOAA guesses anywhere between 50,000 to 300,000 feral cats exist on the island of Oahu alone, releasing billions of eggs into the environment.
“Cat feces is the only way that the eggs of the parasite can get into the environment,” said Amlin. “The parasite can only reproduce in the digestive system of a cat.”
On average, one to three seals a year come down with the disease, and it seems to impact females more than males.
While that may not seem like much, the monk seals are a critically endangered species with only about 1,400 left in the wild — with roughly 300 in the main isles, where they are susceptible to toxoplasmosis.
Sole, also known as RKC1, became the 12th monk seal to die from toxoplasmosis on the Hawaiian isles, according to NOAA, which has been tracking the disease since the late 1990s.
Sole was actually rescued as a prematurely weaned pup in the summer of 2018 on Molokai, where he was born. The Kalaupapa community named him Sole, a Samoan name meaning young boy who is the runner for the high chief.
That year, he was taken to Ke Kai Ola, a monk seal hospital run by The Marine Mammal Center, where he eventually gained enough weight and was released back on Molokai.
Sole was spotted at Oahu shortly after his release, and volunteers kept an eye on him. He appeared healthy just a few days before he was found dead on Jan. 26.
Pohaku, or RO28, meanwhile, was taken in Jan. 22 for intensive care at NOAA’s Ford Island facility after a volunteer saw her floating lethargically off Ko Olina a few days earlier and called to report it. After a few tests, she was diagnosed with toxoplasmosis.
Charles Littnan, division director of NOAA’s protected species division, said the disease is really debilitating for monk seals, which did not evolve with any defenses to it in Hawaii.
“It moves through them like wildfire, and it affects a whole range of organs, neurological tissues, brain, spinal cord, even into their fat layer,” said Littnan. “It is incredibly debilitating, and the animal responds with a terrible inflammation.”
Pohaku was so weak, she was unable to swim or haul herself out of the pool. She has, so far, survived four weeks. She improved enough that NOAA was able to transfer her Wednesday to Ke Kai Ola for longer-term care.
Most monk seals diagnosed with toxoplasmosis die within 48 hours, the scientists said, so there is no precedence for her treatment plan and they are providing her with medications used in other animals to treat similar infections.
It is possible the early intervention made a difference for Pohaku, Littnan said.
Scientists are hopeful Pohaku will survive and one day be released back into the wild, but her future remains uncertain. She may suffer from long-term effects from the disease, they said, and her road to recovery could take months.
To report a sick or injured monk seal, call NOAA’s hotline at 888-256-9840.