Scientists have seen mass mortality events among the coho salmon after they return to streams in Washington state, where half or more die before spawning.
A study published in the journal Science found that stormwater helps carry a deadly chemical, 6PPD, from car tires to nearby creeks and streams. Tire wear releases particles that contain the new chemical 6PPD-quinone, which has proven fatal to coho salmon.
The fish play a vital role in their ecosystem and are of great cultural importance to Native American tribes. And they probably aren't the only species affected.