Lakes and ponds are a significant aquatic feature in Waterton Lakes National Park. Due to the extreme topography, many of these water bodies were fishless prior to historic stocking. Historic stocking practices have highly altered fish
communities. In many locations the presence of nonnative fish is putting native fish populations in jeopardy. In addition, the stocking of fishless lakes has altered food webs and impacted zooplankton, amphibians and possibly avian distribution.This is a simple measure to describe deviations of current lake fish diversity from historic diversity.The lake fish index measures deviations of current lake fish diversity compared with historic lake fish diversity prior to fish stocking.