Could salt be used to control bullfrogs in small ponds?

Authors: David L. Ward, Colton Finch, Heidi B. Blasius

Year: 2008 (xl)

Abstract

New techniques and tools are greatly needed for selective removal of invasive aquatic species. We examined survival of bullfrog, Rana catesbeiana, eggs and tadpoles at 3 parts per thousand (ppt) and 6 ppt salinity in the laboratory to determine if low-level salinity could be used to eradicate bullfrogs from small ponds containing native fish. Bullfrog eggs and newly hatched tadpoles experienced 100% mortality when held at 6 ppt salinity for 10 days. Bullfrog tadpoles 10-15 days old also experienced significantly reduced survival when exposed to salinity of 6 ppt for 10 days. Older bullfrog tadpoles (>9 months old) appeared unaffected by 14 days of 6 ppt salinity. Salinity of 3 ppt did not impact survival of bullfrog eggs or tadpoles at any of the life stages we tested. Adding salt to ponds in the early spring to increase salinity to 6 ppt may be a cost effective way to eradicate bullfrogs from small ponds without harming native fishes.