SAVANNAH, Ga. (AP) — A Georgia agency estimates that a disease wiped out more than 33,000 fish in the Ogeechee River, though scientists still don't know why the fish got sick.

Tim Barrett of the Georgia Department of Natural Resources said Tuesday his estimates show the deaths discovered in late May affected at least 18 species of fish — including sunfish, bass and catfish.

The dead fish were found along 70 miles of the river. Scientists determined they died from a disease that fish normally don't catch unless they're subjected to environmental stress. The Environmental Protection Agency say it's been unable to pinpoint what made so many fish prone to sickness.

Ogeechee Riverkeeper Dianna Wedincamp says so many fish were killed that fishing in the river may not recover for a year or two.