Pollution From Car Tires Kills Salmon On US West Coast, Study Finds | Environment

Pollution from car tires washing up in waterways is contributing to massive salmon kills on the west coast of the United States, researchers have found.

In recent years, scientists have realized that half or more of the coho salmon, also known as the silver salmon, returning to streams in Washington state die before spawning. Salmon, which reach 2 feet in length, are born in freshwater streams before making an epic journey out to sea where they live most of their adult lives. A small number then return to their home streams to lay eggs before dying.

The cause of death has remained a mystery but a new study, published in Science, has apparently found a culprit. When it rains, stormwater carries fragments of old car tires into nearby streams and streams. Tires contain certain chemicals that prevent them from breaking down but are also fatal to coho salmon.

“The salmon would inexplicably die, which is tragic because this beautiful wild animal would have to end its life and then suddenly died,” said Jenifer McIntyre, assistant professor of aquatic toxicology at Washington State University. “The more we look, the more we find it. In some years, not all of the fish we find dead have spawned. “

Samples taken from urban waterways around Puget Sound, near Seattle, and subsequent lab work identified a substance called 6PPD, which is used as a preservative for car tires, like the toxic chemical responsible for the death of the salmon. It is currently not known how it kills the fish, but McIntyre said it was likely an “acute cardio-respiratory problem”.

The discovery suggests that fish and other creatures elsewhere in the United States and around the world are also threatened by the chemical in car tires. The animals are “exposed to this giant chemical soup and we don’t even know what chemicals it contains,” said co-author Edward Kolodziej, associate professor at the University of Washington.

“Here we started with a mixture of 2,000 chemicals and were able to come up with this highly toxic chemical, something that kills big fish quickly and that we think is probably on every busy road in the world,” he said. added Kolodziej.

The nature of the threat to coho salmon has not been clear since the fish were first seen “rolling” downstream, unable to swim upright, in the 1990s, McIntyre said. In an undisturbed riparian area, it would be extremely rare for a coho salmon to die before laying its eggs, but the increasing sprawl of roads, cars and buildings near streams has coincided with an increase in deaths before spawning. Reducing the use of 6PPD or buffers to prevent the flow of pollution could help stem the loss of salmon, McIntyre said.

Coho salmon are federally listed as Threatened or Endangered along the west coast of the United States and have declined significantly in highly developed areas, such as near San Francisco. These are just one of the salmon species facing a range of threats from dams, pollution and the climate crisis.

This summer, federal authorities authorized the culling of hundreds of sea lions along the Columbia River Basin in a desperate attempt to save dwindling numbers of chinook and sockeye salmon. More recently, the US government decided to block a proposed gold and copper mine in Alaska that would have threatened the world’s largest wild salmon run.

“Most species of salmon face a serious threat at least somewhere in their original range,” McIntyre said. “One of my lifelong goals would be to make our cohabitation with them more sustainable. Salmon is beautiful and delicious and important for ecosystems, but it is becoming a rare thing for people to experience.