coho

Action on the toxic chemical from tires

December 13, 2023 By EarthWise Leave a Comment

Since the 1990s, populations of coho salmon in streams and urban creeks up and down the West Coast have been dying in large numbers. Scientists at the University of Washington began studying the mysterious deaths and it took years to figure out what was going on. They analyzed water samples from urban creeks and found that chemicals from vehicle tires were present. By soaking tires in water, they found that more than 2,000 chemicals were present. It took three years to narrow down the suspect list to one chemical: a toxin called 6PPD-quinone, which is produced when the common tire preservative 6PPD mixes with oxygen. It is that chemical that was responsible for the salmon die-off.

6PPD-quinone is toxic enough to quickly kill some fish. Studies showed that concentrations of the chemical in stormwater were found to be lethal for coho salmon following exposures lasting only a few hours.

Despite the discovery, the tire industry has continued to use the chemical in its products. The industry says 6PPD is an antioxidant and antiozonant that helps prevent degradation and cracking of tires in the environment and is essential for the performance and safety of vehicles.

Last year, California regulators directed the tire industry to seek out substitutes for 6PPD. The U.S. Tire Manufacturers Association pledged to investigate possible safer alternatives to the chemical.

In November, spurred by a petition by West Coast tribes whose lifeways depend on coho salmon, the EPA said it will study the impact of 6PPD with an eye to potentially banning its use.

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After Salmon Deaths, EPA Takes Aim at Toxic Chemical Issuing from Car Tires

Photo, posted May 31, 2021, courtesy of Chris Yarzab via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

What’s Been Killing Salmon? | Earth Wise

January 5, 2021 By EarthWise Leave a Comment

For decades, there have been mysterious deaths of Coho salmon. The salmon return from the Pacific Ocean each year to spawn along the West Coast. They can be found from Alaska all the way down into California. After heavy rain events each fall, fish have been turning up dead in huge numbers before they spawn. Normally, less than 1% of adult Coho die before spawning. In these mass death events, anywhere from 40% to 90% of fish can perish in affected streams. The mysterious phenomenon has been the subject of intense research for years.

Recently, scientists announced that they may have solved the mystery. There is a chemical antioxidant known as 6PPD that is used in the manufacture of tires around the world to make them last longer. As tire treads break down over time, they leave behind bits of microplastics on roads. The 6PPD in the plastic bits reacts with ozone to become another chemical: a previously unreported substance called 6PPD-quinone.

That chemical turns out to be toxic to Coho salmon. Researchers have found the presence of 6PPD-quinone in roadway water runoff samples taken from across the West Coast. Based on these observations, they believe it is likely that exposure to this chemical is the main cause of the Coho salmon population decline.

Coho salmon are a favorite of sport fishermen and have great cultural significance to many Native American tribes on the West Coast. The central California Coho population is classified as endangered and three other Coho populations are listed as threatened.

Tire industry representatives call the study results “preliminary” but say the industry is deeply committed to protecting the environment. A safe chemical substitute for 6PPD is clearly needed.

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Salmon have been dying mysteriously on the West Coast for years. Scientists think a chemical in tires may be responsible

Photo, posted November 17, 2011, courtesy of Lynn Ketchum/Oregon State University via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Shrinking Alaskan Salmon | Earth Wise

September 24, 2020 By EarthWise Leave a Comment

According to a new study published in the journal Nature Communications, salmon returning to Alaskan rivers have become significantly smaller over the past 60 years. As a result of climate change and competition from hatchery fish, wild salmon are spending less time at sea and are returning to spawning grounds at younger ages.

The study, by scientists at the University of Alaska at Fairbanks and the University of California Santa Cruz, examined measurements of over 12 million fish collected by the Alaska Department of Fish and Game from 1957 through 2018. Over that time period, four out of Alaska’s five wild salmon species – Chinook, chum, coho, and sockeye – have shrunk in size. Chinook salmon is the official state fish of Alaska and they used to stay out at sea for seven years before returning to spawn. Many are now returning to rivers at just four years old and are on average 8% smaller than they were 30 years ago.

The shrinking size of Alaskan salmon has consequences for people, the economy, and ecosystems in Alaska. Wild salmon is a staple food for many residents of the state, particularly among indigenous groups. More generally, Alaska produces nearly all of the wild salmon in the U.S. Commercial fishing of over 200 million wild salmon in 2019 resulted in $657 million in income. The fish are also an important food source for bears and other wildlife and the spawning migration of salmon plays an important role in nutrient transportation in Alaskan river ecosystems.

Multiple factors are driving the changes in the salmon population, but the largest effects are the changing climate and the abundance of salmon in the ocean due in part to hatchery production that results in competition for the salmon’s food.

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Alaska’s Salmon Are Significantly Smaller Than They Were 60 Years Ago

Photo, posted September 5, 2019, courtesy of Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.