KEY POINTS

  • Research has found that the salmons die even before spawning
  • The harmful chemicals in the stream water can be dangerous to other aquatic beings
  • The samples for the research were taken from urban streams around Puget Sound, near Seattle

Pollution from car tires that wash into streams are the main cause for the mortality of salmon on the US West Coast, a study has found. 

The mass die-off of Coho Salmon, also known as Silver Salmon, have been found due to the fragments of old car tires that flowed into the water. It was found that the shoals of salmon that return to the streams of Washington state were dying even before spawning. 

These salmon, which are two feet in length, are generally born in freshwater streams before they venture out to the sea to live their adult lives. Some of them return to streams that are nearby to lay eggs before dying.  

Initially, the death of this particular species of salmon remained a mystery until a recent study, published in Science, solved the conundrum. The study found out that the stormwater carries fragments of old car tires into creeks and streams that are nearby. These tire fragments had harmful chemical substances that did not breakdown even after reaching the stream and that proved deadly to the Coho Salmon.  

Speaking about the issue, Jennifer McIntyre, assistant professor of Aquatic Toxicology at Washington State University, said, “The salmon would be inexplicably dead, which is tragic because this beautiful wild animal should be culminating its life and then it’s suddenly dead. The more we look, the more we find it. In some years all of the fish we find dead did not spawn," reported The Guardian.

The samples for the research study were taken from urban streams around Puget Sound, near Seattle. After careful observation, the analysis concluded that a substance called 6PPD, which is generally utilized as a preservative for car tires, was found in the samples. The cause of death due to this toxic chemical substance is still unknown but McIntyre said it can be due to “acute cardio-respiratory problem.”

The findings of the study also mention that apart from the salmon, other aquatic creatures in the U.S. and around the world also may be found at risk due to the chemical from the car tire. Animals are being “exposed to this giant chemical soup and we don’t know what many of the chemicals in it even are," said Edward Kolodziej, the co-author of the study, who is also an associate professor at the University of Washington. 

“Here we started with a mix of 2,000 chemicals and were able to get all the way down to this one highly toxic chemical, something that kills large fish quickly and we think is probably found on every single busy road in the world,” he added. 

The Coho Salmon is listed as either threatened or endangered along the US West Coast and have reduced in number from the highly advanced areas, such as places as near as San Francisco. These are some of the species of salmon that face many threats from dams, pollution and climate crisis.  Coho Salmon Coho Salmon Photo: Pixabay

In a bid to save the Chinook and Sockeye salmon, the federal authorities had sanctioned to cull of hundreds of sea lions along the Columbia River basin this summer. In another related incident, the US government had decided against a proposed gold and copper mine in Alaska that would have put the largest wild salmon run at risk. 

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