Campaigners want to restore fish passage on the Klamath River

The delegation claims the number of salmon returning to spawn in the River Klamath has plummeted since the building of a complex of dams.

The dams are owned by PacifiCorp, a Scottish Power subsidiary.

The Karuk, Yurok, Hoopa, and Klamath tribes are campaigning alongside US environmentalists and fishermen.

The delegation plans to attend Scottish Power's annual meeting in Edinburgh on 23 July.

Their economies, cultures and religion revolve around the annual return of the salmon Campaign group spokesman

The group is demanding the restoration of the River Klamath in Oregon, which they claim has been damaged by the 350-mile dams project.

The work has degraded water quality and contributed to a large decline in salmon numbers in what was once America's third greatest salmon river, they claim.

A spokesman for the group said the four tribes had lived along the banks of the Klamath river for thousands of years.

"Their economies, cultures and religion revolve around the annual return of the salmon," he said.

More than a million fish used to return annually, but today 100,000 returning fish is considered good, he said.

Co-operating

Two salmon species have already become extinct, he added.

The campaigners intend to base themselves in Edinburgh for several weeks, during which they will demonstrate at the company AGM, meet politicians, and brief environmental and human rights groups.

Scottish Power said its subsidiary has to take into account the views of various groups including farmers who value the irrigation provided by the dams, recreational users, and electricity customers.

The company also argues that the water flow is controlled by the federal government rather than by PacifiCorp.

A consultation is under way and has two years to go.

The company claims it has a long history of co-operating with the tribes.

A Scottish Power spokesman said: "The delegation will be welcome at the AGM as shareholders.