(Newser) – Approximately 10,000 scrotum frogs are dead near Lake Titicaca. And there's nothing funny about that. Seeker reports thousands of the frogs—scientific name Telmatobius culeus—have been found dead and floating along 30 miles of Peru's Coata river, a Lake Titicaca tributary, in recent days. The scrotum frogs, so named because of the baggy skin that helps them breathe in the thin air of their natural habitat, are "critically endangered," according to CNN. Experts say the scrotum frog population has shrunk by 80% over the past 15 years due to habitat destruction, the introduction of North American trout into Lake Titicaca, and locals over-harvesting the frogs for food. But no one is quite sure what's behind the recent mass die-off.

Environmentalists, who brought 100 dead scrotum frogs to the regional capital's town center in protest, blame sewage runoff from a town near the river. Sludge and solid waste have been seen where the frogs live. "They have no idea how major the pollution is," Seeker quotes the leader of the protest as saying. "The situation is maddening." The Committee Against the Pollution of the Coata River says the government has ignored residents' demands for a sewage treatment plant in the area, the BBC reports. According to CNET, the Peruvian National Forestry and Wildlife Service is investigating the recent deaths. It's important authorities find an answer, as scrotum frogs live only in the waters around Lake Titicaca. (Toughie the frog, likely the last of his species, has died.)

