In a photo posted to social media, the lesions appear as dark, bubbly splotches on the underside of a turtle's namesake shell.
They first appeared last summer in several ponds in Salem County, according to Larry Hajna, a spokesperson for the New Jersey Department of Environmental Protection (NJDEP).
Authorities don’t know yet if the lesions are cropping up on turtles again this year, he told Fox News, because a combination of the cooler spring and the COVID-19 outbreak have hampered surveillance efforts so far this season.
“It was there last year, could be back this year,” Hajna said.
And authorities have no idea what’s causing the lesions, he added.
So they’re asking for the public’s help locating more examples. By casting a wider net, investigators could also determine whether the condition is confined to just those ponds in Salem or if it is more extensive.
The NJDEP is asking anyone who finds an afflicted turtle, whether it be a redbelly or another species, to report its location, the total number of turtles seen and any other relevant observations -- such as whether the animals are exhibiting abnormal behavior, the conditions of nearby water and if there are dead fish or amphibians nearby.
Redbellies range in size from around 10 to 16 inches, making them the largest basking turtle in their area, according to the New Jersey Division of Fish & Wildlife’s website. As the name implies, they have red-shelled bellies. From the top, their shells are usually dark.
They generally live around ponds, lakes, rivers, streams, ditches and brackish marshes, according to authorities, and they are active between March and October.