Nov 8 (Reuters) - U.S. commercial fishing groups on Wednesday sued 13 tire manufacturers in California, saying a chemical used in their tires is poisoning West Coast watersheds and killing rare trout and salmon.

The Institute for Fisheries Resources and the Pacific Coast Federation of Fishermen's Associations sued Bridgestone Corp , Continental, Goodyear Tire & Rubber, Michelin and others in San Francisco federal court, alleging a chemical used in their tires known as 6PPD is killing protected salmon and trout in violation of the Endangered Species Act.

The fishing groups said the chemical, which becomes toxic when it degrades, is released from tires as vehicles drive around and park. They said the degraded chemical can be flushed into waterways during storms, where it kills protected salmon and trout.

Declining fish populations have led to restrictions on commercial fishing, the lawsuit said.

The lawsuit said researchers have identified the degraded form of 6PPD as causing salmon mortality, and that scientists believe trout and other fish are also likely being killed by the chemical.

The groups, which say that pollution has decimated their industry, want the court to issue an injunction barring the companies from manufacturing tires with the chemical without first taking measures to protect fish and watersheds.

The tire manufacturers did not immediately respond to requests for comment on Wednesday.

The lawsuit is the first in the U.S. to target tire manufacturers for their use of 6PPD, which is found in nearly every tire on the planet, according to Elizabeth Forsyth, an attorney for the fishing groups with the environmental law firm Earthjustice.

Forsyth said the lawsuit focuses on West Coast impacts from the chemical, but that she expects there will be further scientific evidence tying the chemical to damages elsewhere in the future.

The U.S. Environmental Protection Agency said earlier this month that it would take steps to regulate the chemical, which has been used in tires for decades and acts as a stabilizer to prolong the life of rubber. The EPA said exposure to the chemical can kill fish within a few hours.

In July, California's Department of Toxic Substances Control adopted a rule requiring tire manufacturers to evaluate safer alternatives to 6PPD, noting the threat to coho salmon.

Together, the 13 tire manufacturers sued on Wednesday account for 80% of the domestic U.S. tire market, according to the lawsuit. (Reporting by Clark Mindock, Editing by Alexia Garamfalvi and Sandra Maler)