Environmental authorities are investigating yet another fish-kill on the Shenandoah River, the latest in a puzzling trend of die-offs plaguing a key Virginia waterway upstream of the Potomac.

Dead northern hogsuckers were discovered along the Potomac River tributary in Clarke County earlier this week, said Jeff Kelble, Shenandoah Riverkeeper and a member of the Shenandoah River Fish Kill Task Force.