A Hawaiian monk seal being treated for toxoplasmosis at a marine mammal hospital has died. The male was one of just four of Hawaiian monk seals (Monachus schauinslandi) to be rescued prior to death from the disease, which is spread by Hawaii’s feral cat population. Known as RW22, the Hawaiian monk seal was rescued after being found with fishing line in his mouth off the island of Oahu. Biologists discovered it also had symptoms of toxoplasmosis, a disease spread into the environment exclusively via cat feces. Researchers believe monk seals become exposed by swallowing contaminated water or prey. One study found Oahu has an estimated 300,000 feral cats.

With no vaccine available for toxoplasmosis, preventative measures must be taken by the general public. Toxoplasmosis is one of the main threats facing the endangered Hawaiian monk seal population on the Main Hawaiian Islands, in part due to the infection being difficult to detect. Other main threats to monk seals include negative human interaction and fisheries interaction via hooking and entanglements. Only three other seals impacted by toxoplasmosis have been rescued prior to death. An estimated 1,300 Hawaiian sea monks exist in the wild.

Photo: A Hawaiian monk seal was being treated for toxoplasmosis before its death.
Credit: The Marine Mammal Center