An invasion of trout at the Yellowstone Lake has affected wildlife populations throughout the National Park's ecosystem, scientists have found. The sea trout, which was first discovered in Yellowstone in 1994, caused population changes in predators, including bald eagles, osprey and grizzly bears – unexpected effects that were never previously documented by scientists.
Yellowstone Lake has a native population of cutthroat trout that plays a vital role for the wider food courses in the park. These fish consume zooplankton from deeper in the lake, so they are eaten by predators.
The worry of sea trout disrupted this "pristine ecosystem." In a study published in Science Advances has now elaborated to what extent.
Todd Koel, a scientist with the National Park Service (NPS) and lead author of the study, said the sea trout was intentionally introduced to Lewis Lake in Yellowstone in 1
"The effect of sea trout on native fish in western American lakes was actually well documented in locations outside Yellowstone, so when first discovered in Yellowstone Lake in 1994, it was understood that the effect on native cutthroat trout could be seriously, "he told Newsweek .
"However, the effects of sea trout on the connected bird and terrestrial food pathways were not documented earlier. Effects of introduced predators such as sea trout were assumed to weaken across ecosystem boundaries. Instead, we experienced strong cross-border effects. The aquatic border as native snowdrift consumers, including bald eagles, island ridges, grizzly bears, black bears and river tigers, were lost, displaced and / or forced to switch prey in the absence of black trout.
The problem of sea trout and its impact on indigenous populations is well known and efforts In 2017, an article from NPS said that the scale of the issue remains enormous and that the species successfully There are several areas created: "Yellowstone Lake provides near perfect spawning and breeding grounds for trout with few natural predators present … Reduction of sea trout population to a level that will only have less impact on the cutthroat trout population is assumed to take at least 2025, provided we maintain current high levels of repression efforts. "
In the latest study, the team examined data on populations of sea trout, cutthroat trout and other indigenous populations from over four decades, revealing the shift in patterns that arose after the sea trout invasion. Studies showed that sea trout also had a negative impact on Between 1987 and 1991, on average, there were 38 nest, but in 2013 to 2017 there were only 3. The number of bald eagle reasons also fell from 11 in 2004 to 2008 to eight in 2013 to 2017
Oysters in the Yellowstone Lake proved to be seeking alternative food sources, with the species now predating amphibians and longnose suckers, their numbers also appear to have decreased: "Abundance was estimated as an otter per kilogram." . The 13.4 km shoreline in 2008, which is among the lowest reported for a river change population, "writes the team, but noted that" estimates do not exist for periods before the cut trout decline. "
The researchers said that both grizzly and black bear populations had to seek alternative food sources due to the fall of black trout, which seems to have led them to hunt more elk calves migrating to the interior of Yellowstone each spring.  [The biggest concern about the findings are] the far-reaching negative effects of a single introduced predator on otherwise untouched ecosystems located in the highly protected landscape of Yellowstone National Park, "Koel said. "While we are making great strides in suppressing the invasive sea trout and restoring the original black trout, there remains uncertainty about our ability to completely restore these aquatic and terrestrial ecosystems to eradicate trout conditions."
Yellowstone Park authorities have a program instead of trout and abundance of invasive species, Koel said. "At present, technology does not exist for us to completely eradicate the sea trout from Yellowstone Lake, so the suppression of garnishment or other technologies as they evolve will be required in the foreseeable future to maintain native cut trout and the natural function of these ecosystems," he said.
This article has been updated to include more information on sea trout.