The lack of rain and resulting low flow of the Russian River pose a threat to endangered coho salmon, which are having difficulty reaching their spawning grounds and could be caught and killed by fishermen.

Biologists are concerned about any harm done to coho, a fish which is being coaxed back from the brink of extinction but still numbers only in the hundreds.

A major difficulty brought by reduced rain is the fish are still in the Russian River's main stem rather than in the tributaries where they are usually spawning by now.

As a result, the Sonoma County Water Agency is distributing 20,000 cards with pictures and identifying characteristics at places where fishing licenses are purchased, in addition to the 20,000 printed two years ago.

"We kept hearing from people that there were coho in the river and we were hearing that the anglers would not be able to tell the difference and they would keep the coho," said Ann DuBay, water agency spokeswoman.

Bill Laurie of Santa Rosa, president of the Russian River Fly Fishers, said most fishermen know the difference, that coho have black mouths and steelhead have a white mouth. But he also acknowledged that the concerns of biologists and regulators are warranted.

"There are poachers and people who don't know how to tell one fish from another and there are people who don't care," Laurie said.

Two years ago, a picture of an angler holding a coho was displayed on the Internet page as part of the annual Russian River steelhead fishing contest.

Coho are in the Russian River now, but the low flow has cut them off from many of their tributaries, such as Grape, Green Valley and Mill <NO1><NO>creeks, where they go to <NO1><NO>spawn.

Instead, the coho are holding in river pools alongside steelhead that are legal to fish for and are now in the river in abundance.

The situation might change next Tuesday and Wednesday, when there is a chance of rain in the North Bay for the first time in January and following a December rainfall that measured in the 10ths of inches.

And that keeps coho in harm's way, said Mariska Obedzinski, who is monitoring the coho recovery program for the UC Cooperative Extension.

"There is so much invested in bringing these coho back, from the hatchery program to the restoration work in Dry Creek to the monitoring," Obedzinski said. "For someone to go out and accidentally catch one when they are in the river, when they could kill or harm them, it is discouraging."

<NO1><NO><NO1><NO>There are 123 adult coho that have been photographed this year swimming through the water agency's fish ladders near Forestville — four times the number seen last year.

As few as three of the fish, which are on the federal endangered species list, were seen in the Russian River returning to spawn in 2004.

Biologists say that coho are native to the Russian River system and are genetically distinct from the coho in any other California river.

There is a misconception that the coho today are not native, but the result of a program years ago in which coho from the Noyo River were planted in the Russian River.

Those Noyo River fish didn't survive, however, Obedzinski said.

For the past 10 years, coho have been raised from wild fish at the Warm Springs Dam hatchery in a program being run by the Army Corps of Engineers.

This year, 175,000 young coho were released into the tributaries of the Russian River. The program costs about $700,000 a year.

The Sonoma County Water Agency also has spent $2 million studying and drawing plans to improve the habitat in Dry Creek, a project that could cost $6 million to $7 million a mile.

Other work has been done by the Sotoyome Conservation District, $7 million, and the Gold Ridge Resource Conservation District, $1.5 million, to control erosion, create off-stream reservoirs and alternative frost-control measures.

You can reach Staff Writer Bob Norberg at 521-5206 or bob.norberg@pressdemocrat.com.