On Halloween weekend, the spirits of long-dead mountain men can be heard chopping down trees on Massanutten Mountain and the fish that haunt the Shenandoah River assume disguises clever enough to fool all but the sharpest anglers. Some float by like giant oak leaves. Others come out of the water, snagged on fish hooks, looking exactly like green clumps of grass. Robbie Leibner caught one that most people would have mistaken for a tree limb.

"I'd call that a whopper," said Leibner, who had used a plastic worm and inspired casting to hook a fish that magically transformed itself into the branch of a sycamore tree. "Could be a record for this river."

The Shenandoah is a river that does not depend on Halloween for magic. If you like to fish, this historic river, running parallel to Skyline Drive about 70 miles west of Washington, is notoriously rich with small-mouth bass. For canoeists, there are few rivers in the east as mild and pretty.

This day, with a bright sun illuminating hills that were already ablaze with red and yellow and a warm breeze carrying the faint, sweet smell of decaying leaves, the Shenandoah seemed bewitching.

"On this kind of day you can't stop smiling," said Dave Jackson, whose smile was barely a grin compared to his wife Julia's. She and her husband, who live in McLean, had just paddled for two hours down the Shenandoah in a second-hand canoe they bought that morning.

The Jacksons were among a hundred people from half a dozen states who came to the south fork of the river this weekend for the annual Shenandoah Outfitters canoe auction. The auction began about 10 years ago, three years after Joe Sottosanti fled suburban Washington and his job as an insurance salesman to start the canoe rental company.

"I got into this because my hobby was eating weeds and living off the land," said Sottosanti, whose company now markets its own model of canoe, the Shenandoah, which is built in a workshop behind the rental concession. "Then the movie 'Deliverance' came along and the canoe business went kaboom. Everyone is masochistic. They want to destroy themselves on a river."

Leibner and I had planned to rent a canoe for a float fishing trip down the river. But the auction put that idea under water. We had also planned to be on the river early enough to see the sun climb above it. A leaky fuel line on Wisconsin Avenue scuttled that attempt. Since neither of us had brought waders, we were confined to a few public areas beside the river where the trees had left a little casting room.

"The fish will come to us," said Leibner, a 29-year-old Washington lawyer with dark curly hair and a tendency to get tangled up in evergreens. "We are in total control."

Leibner is one of fishing's rare catches, a late bloomer. Growing up in Brooklyn and Long Island, the closest he came to fishing was bobbing for apples at preteen parties. He was almost an adult before he saw a fish with the head still on it.

Five months ago he got hooked worse than any fish he's caught since. Now he dreams about fish, can't pass a magazine rack without leafing through the latest issue of Field and Stream and has begun taking his fishing gear to work with him in case a sudden, midday illness forces him to return home, by way of the Potomac.

"My wife really encouraged me with the fishing," said Leibner. "She felt I needed a hobby. There were days I was coming home from work ready to kick the dog. I think now she realizes she created a monster."

Leibner works for the Washington Legal Aid Society. His workload includes a wide range of cases, many of them messy and emotionally charged.

"I deal with so much stress and ugliness in my job, if I can spend a few hours beside a river and think of nothing else but fishing, it's fantastic," said Leibner.

Leibner fishes like a man piecing together a jigsaw puzzle. When one lure fails, he has a dozen more to try. In his shiny new tackle box he has rubber frogs and lizards, plastic worms, spinners, poppers and plugs. Each lure requires a different fishing technique, from bottom bumping to surface skimming.

By the time the full moon rose over the mountain ridge across from us, we had caught dozens of leaves, limbs and trees. We let all of them go.

"Can you imagine how big this will be by next year?" Leibner said, watching his sycamore limb swim downstream. "I'll have to remember to bring stronger fishing line next Halloween."