Americans spend almost $100 billion a year on fishing, creating jobs and revenue for communities across the country.But as climate change makes rivers warmer, that industry is increasingly threatened. Recent research found 87% of rivers studied across the U.S. and Europe are warming, with 70% losing oxygen. "What climate change does is it's starving the oxygen out of the water. It's raising the water temperature and it's killing off trout," said Brian Sheppard, who is a guide on the historic Beaver Kill River in New York's Catskill Mountains. He is part of a $750 million U.S. fly fishing industry, but he's finding it harder to make a living."This is the home of American fly fishing," he said. "It's pretty cool. It's hallowed ground."While he once took clients out all summer, now the water temperature is frequently over the threshold for good fishing."Nowadays we're hitting that for two to three months out of the year in the middle of summer," Sheppard said. "You catch one of these fish and it will kill them right away."Nonprofit helps protect the river and fishing tourismJeff Skelding, the executive director of Friends of the Upper Delaware River, said fewer fish to catch can harm the local fishing-tourism economy."If you go to the museums around here, you'll see pictures of people catching hundreds and hundreds of brook trout out of these streams," Skelding said. "That has changed, you're not going to do that anymore."Rivers are cooler the faster they flow. Skelding's nonprofit works to restore the flow by removing old dams and reinforcing banks to keep them from filling up with sediment."The impacts of climate change, erosion, sedimentation, development threats ... the problems that these rivers are experiencing are not very different than we see in many, many other parts of the country," Skelding said.For Sheppard, it's worth protecting as the changing climate changes his industry."It's actually about introducing people to a way that their life can improve and we try to expose them to the magic of this place so that they'll save it," he said.