How Coal and Metal Mining Affects Salmon and Trout in Northwestern North America

In a recent essay, the effects of metal and coal mines on salmon and trout in northwest North America are summarized, emphasizing the need for more thorough and open research to guide mining policies.

This is the first thorough study by a multidisciplinary team of specialists that directly connects mining policy to what we now know about watershed ecology and salmonid biology.

Mining on fish warrants

(Photo : LUIS TATO/AFP via Getty Images)

While describing existing environmental issues and shortcomings in the application of science to mining governance, this research does not advocate for or against mining.

According to main author Chris Sergeant, a graduate student at the University of Alaska Fairbanks College of Fisheries and Ocean Sciences and a research scientist at the University of Montana, "We feel it will give vitally needed scientific clarification for this contentious subject," as per ScienceDaily.

Experts combined and examined data on hydrology, river ecology, aquatic toxicity, biology, and mining policy for the research.

More than 3,600 mines are mapped by their thorough investigation over Montana, Washington, British Columbia, the Yukon, and Alaska. The mines range in size from small, family-run placer operations to enormous open-pit operations.

The study demonstrates that mines continue to impair salmonid-bearing watersheds through pollutants, stream channel burying, and streamflow change despite impact studies meant to evaluate risk and guide remediation.

Silt suffocates eggs, and polluted groundwater may not allow embryos to survive. Salmon's sense of smell is impaired by heavy metals, which hinders their ability to detect predators and navigate back to the ocean to spawn.

Our analysis showed that while not all mines are equally dangerous, the damage caused by mining may be significant and pervasive. In order to appropriately estimate the danger to water, fish, and communities, it is crucial to consider the number of mining impacts on these watersheds, according to Sergeant

The report also explains how certain mining regulations fail to take into consideration the depth and duration of mining's environmental consequences, as well as the growing implications of climate change.

The main problem is that salmon depend so heavily on the watershed for their whole life cycle. Unlike mining initiatives, which tend to be extremely regionally focused and do not adequately take into account all of the compounding and downstream consequences of mining, they migrate throughout watersheds.

Megan McPhee is a faculty member of CFOS and a salmon scientist.

She clarified that some impact analyses don't completely evaluate the infrastructure necessary to run a mine, such as roads, energy production, and water removal.

Another factor is that most mines must be permanently mitigated after closure. That's an issue since that's not how the majority of corporations are set up. Additionally, according to McPhee, the majority of mitigation methods do not account for environmental change, such as permafrost melting and floods brought on by climate change.

How mining activities affects fish species?

Mining activities can introduce pollutants, cause erosion and runoff, change the course of water flows, or negatively affect biodiversity in aquatic ecosystems, among other pressures, as per Faunalytics.

The authors of this study set out to describe how mining for coal and other minerals affected fish habitats in three significant stream ecosystems, the Temperate Plains, Southern Appalachia, and Northern Appalachia.

By counting the number of mines, their density, and the condition of the fish habitat in the three ecosystems, they were able to quantify these consequences.

Additionally, they contrasted these impacts with those of similar but unrelated human-made disruptions, such as the use of urban and agricultural land.

Thirty percent of the differences between least-disturbed values and actual observed values were statistically significant.

A disparity was expected to be substantial at the ecological scale as well if it was significant at the local level.

In areas with modest mine density, 15 percent of all comparisons had substantial disparities, almost half of which were discovered.

This implies that even a single mine may have a big effect on how healthy stream fish habitats are.

Nearby mine concentrations with the potential to impair the health of fish habitats were present in around 25% of Northern Appalachian streams, 50% of Southern Appalachian streams, and 34% of Temperate Plains streams.