Trout fish declined drastically due to climate change

Ground Report | New Delhi: Trout fish climate change; Climate change is driving the decline of native trout by reducing stream habitat and facilitating the spread of invasive trout species. It is the finding of a new study published in Science Advances by researchers at the University of Montana (UM).

In a new study published in Science Advances, researchers at the University of Montana found that climate change is driving declines in native trout by reducing stream habitat and facilitating the spread of invasive trout species.

To answer those questions, scientists from UM, the US Geological Survey, and Montana Fish, Wildlife & Parks quantified the impacts of climate change on the distribution of five trout species in the northern Rocky Mountains. They used an extensive set of long-term data collected and maintained by the Montana FWP, analyzing nearly 22,000 data points from electrofishing surveys in Montana's streams and rivers over the past 30 years.

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The researchers found that the occupancy of native bull trout and west slope cutthroat trout, defined as the number of streams where a species is present, decreased by 18% and 6%, respectively, between 1993 and 2018, and was expected to decline by 39% and a further 16% by 2080. Although invasive brook trout were also expected to decline, invasive brown and rainbow trout have expanded their range due to rising water temperatures and seem to be ready to thrive during future climate change.

The culprit for the decline in both native trout species is likely climate change, the researchers found, but the specific mechanisms of the decline varied by species.

Bull trout, a threatened species under the Endangered Species Act, requires cold streams with adequate flow. But warmer water temperatures and lower water levels in summer, both driven by climate change, have degraded stream habitat and likely caused bull trout declines. Meanwhile, western slope cutthroat trout was heavily constrained by the presence of invasive trout species, including brook trout that can compete with native trout and rainbow trout that readily hybridize with slope cutthroat trout. West. The threat of invasive rainbow trout is particularly concerning as its range is expanding due to global warming.

"Our two native trout species in Montana will decline in the future unless proper conservation measures are taken," said Bell. "Our results suggest that adapting conservation strategies to specific species and specific threats of climate change is important for the conservation of native fish."

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For example, conserving bull trout in streams and rivers may be better geared towards protecting, reconnecting, and restoring critical cold-water habitats. On the other hand, suppressing invasive trout species is likely to be more effective in conserving West Slope cutthroat trout.

"Globally, climate-induced changes in aquatic habitats are projected to threaten at least a third of freshwater fish, and some invasive species could take advantage of such changes," said Clint Muhlfeld, USGS scientist and co-author. of the study. "These scenarios appear to be playing out in our backyard with native and invasive trout."

The study also highlights the importance of using and maintaining long-term data sets that cover large regions to shed light on the complex ways that climate and invasive species work together to affect native species.

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