January 4, 2009

Calif. tries to restock salmon river

Researchers are trying to restore salmon to a river in California with fish bred to increase their chance of survival in the wild.

The California Department of Fish and Game released 305 young Coho salmon in the Salmon River in Sonoma County, The San Francisco Chronicle reported. Despite the river's name, salmon vanished 30 years ago because of environmental degradation.

We are trying to develop fish with good strong genetic makeup that will lead to a durable natural population, said Gail Seymour, a biologist and watershed planner with the department. We don't know for sure that we are going to have full recovery by planting this minimal number of fish. It hasn't been that long since we've known that diverse genetics are so critical.

The released salmon come from two different populations, the Russian River and Olema Creek in Marin County.

Biologists said Coho salmon are more sensitive than their relatives to changes in water temperature and quality, and their numbers are dropping sharply. With so few fish, maintaining genetic diversity becomes a problem.

Bob Coey, a senior biologist, said by taking fish from the Russian River population to the north and Olema Creek to the south, the department is trying to reproduce the genetic mixing that occurred naturally in Salmon Creek in the past.