The height of the summer recreation season was just about to begin for the Yellowstone River economy. Every August and September, thousands of tourists arrive in Montana to enjoy the pristine scenery of America’s last undammed river. But this year, what they found instead, was the stifling smell of rotting fish so numerous that the normally free-flowing river seemed clogged. Something was horribly wrong.
Anglers and tourist guides reported dead fish floating on the river. More and more fish were washing up on shore, and not in one area, but up and down 183 miles of the Yellowstone. The state organization in charge of the health and maintenance of the river, Montana Fish, Wildlife, and Parks, scrambled to find the reason to explain the huge die-off. To close the river for an indefinite time was unprecedented, but this is just what they had to do. The river was shut down on August 19th, 2016.
The Yellowstone river system is home to sought-after trout, but the particular species of interest is the less desirable mountain whitefish.
“They may not be a popular a game fish but they certainly are an intricate part of the environment and certainly part of the food chain for our popular trout species in the river,” said Scott Opitz, the fisheries biologist for Montana Fish, Wildlife and Parks.
After the river was closed, whitefish were suddenly the most talked about fish species in the river. Unfortunately, it was not for good reasons. By September 2nd, over 4,000 fish bodies were counted in one area, but Montana officials estimated the actual death toll was in the 10,000 range. The culprit was found in the gills of the infected fish.
Tetracapsuloides bryosalmonae is a microscopic parasite that causes proliferative kidney disease in salmonid populations. It lives in river sponges, called bryozoans, and fish. The sponge is where the virus reproduces, but it relies on fish to complete its life cycle. Its infectious stage is microscopic spores. The spores enter through the gills, eventually reaching the kidneys and causing death. It can cause up to a staggering 90% loss in fish populations. Not too much is known about this parasite, as it’s close relative Myxobolus cerebralis, which causes whirling disease in fish, has dominated much of the spotlight. Tetracapsuloides bryosalmonae is in the same family of myxozoans, whose closest relatives include jellyfish, corals and sea anemones.
While there had been outbreaks of this parasite before in the western part of the United States, most famously in 2011 and 2012 in Idaho, there had never been one of this magnitude. For one thing, the parasite was much more prolific in this case, overwhelming the mountain whitefish population. The outbreaks in Idaho, still ongoing, have not been nearly as severe, and researchers have a pretty good idea the reason why.
The Yellowstone River is still free, while the rivers infected in Idaho are dammed. The river temperatures of dammed rivers are cooler, and the flow controlled. The Yellowstone is suffering under the effects of climate change, with near-record low-flows and recorded water temperatures that are 15 degrees Fahrenheit above what is ideal for trout and whitefish. The whitefish likes cooler temperatures, with the spawning season occurring in the fall unlike most other fish species.
Meanwhile one of the main sources of income for the state, recreation on the Yellowstone, was already having significant consequences for the fishing guides, raft companies, hotel, and restaurants in the area. The governor’s office declared a state of emergency during the crisis, which opened up funds to pay unemployment insurance, but many of the independent contractors, such as fishing guides, would not be eligible. The final weeks of the summer season are crucial for many small businesses.
“We went from being very busy to almost nothing in just three days,” said John Bailey, owner of Bailey’s Fly Shop in downtown Livingston. “What will be interesting is how people get through the winter.” Many people had lost their jobs, in a small town with very few employment options.
Where the river passes through Park County, the University of Montana’s Institute for Tourism and Recreation Research estimates that guiding and outfitting accounts for nearly $20 million of annual visitor spending. To shut down the river, even for just a short time, impacts all the people in the region.
The implications of the Yellowstone die-off are huge, but even worse is the uncertainty that this could happen again next year, and the severity could again cause major closures. Economically, local businesses would be unlikely to survive closures in two seasons.
“If it happened again next year, people would never come here again,” Bailey said. Tourists “would take it off their list to come. It would be too high a risk. You don’t plan your vacation where you can’t go.”
There is concern for the future however. In Idaho, each year in August when it gets hot, the parasite flares up again, but the severity has declined each year as the fish develop resistance to the bug. But Idaho’s outbreak was not near as severe as the Yellowstone, so it could be that if and when the parasite flares up again, consequences could be greater as a result.
“The long-term forecast for this disease appears that this is going to be something that we’re going to continue to live with,” said fisheries biologist Scott Opitz. “There’s no silver bullet. Odds are very high that we’ll continue to see annual outbreaks of mortality.”
The bottom line is, no one really knows what the future of the Yellowstone River looks like, but it is clear that the consequences of global climate change are not in the future anymore; we are seeing the results now.