As an avid birder and bird photographer, Kelly Preheim is a frequent visitor to the Lake Andes National Wildlife Refuge near her South Dakota home of Armour.\r\n\r\nBut birds weren't the focus for her on a recent visit, fish were. Frozen fish. A wall of frozen fish.\r\n\r\nPreheim snapped a photo of the bizarre scene, and it was posted on the U.S. Department of the Interior Facebook page.\r\n\r\n\r\n\r\nPreheim explained that the water level of Lake Andes was low because of the drought and the lake experienced a massive fish-kill due to depleted oxygen levels.\r\n\r\n"When the thick ice forms on the lake's surface, it blocks out the sun, and the algae\/plants don't photosynthesize and produce oxygen, thus depleting oxygen levels," she wrote.\r\n\r\n"If the aquatic plants and algae subsequently die and decompose, this also uses oxygen, further depleting levels, so the fish essentially suffocate from lack of oxygen. The fish died and floated to the surface."\u00a0\r\n\r\nRELATED: Frozen fish placed in tub of water is brought back to life; video\r\n\r\nThe lake mainly has common carp and black bullhead but is said to also have northern pike, yellow perch, bluegill, orangespotted sunfish and green sunfish.\r\n\r\nSo how did the frozen fish become a wall of frozen fish?\r\n\r\n"When the weather turned even colder, the ice expanded pushing it toward the shore where it buckled and went vertical," Preheim said. "Or it may have been driven there by very strong winds."\r\n\r\nThe wall of frozen fish and other fish lying about made for easy pickings for hundreds of bald eagles, gulls and crows, all of which feed on dead fish.\r\n\r\n"It was quite a sight and it smelled very fishy out there for quite a while," Preheim added.