Trout raised in hatcheries can pass a deadly fungus to amphibians, researchers have found. The discovery bolsters suspicion that stocking lakes for sportfishing could be contributing to a global decline in amphibian populations.
Since the 1980s, for example, the numbers of western toads have plummeted throughout much of their range in the western United States and Canada.
A few years ago, Joseph Kiesecker at Pennsylvania State University in State College and his colleagues got a glimpse of one cause of western toad mortality. They found that some stocked lakes had high concentrations of a fungus called Saprolegnia ferax. This microbe produces a fish disease that's common worldwide and a huge problem in fish hatcheries.