BOISE, Idaho — Fish counters at Bonneville Dam have posted the highest numbers of the season for spring chinook salmon, with 6,065 swimming through the first Columbia River fish ladders they encounter as they head inland from the Pacific to spawn.

The Thursday tally was more than double Wednesday's total of 2,542.

The next-best day was April 25, when the count was 4,149. Spring chinook, also called kings, can weigh as much as 50 pounds and are prized by anglers.

"We finally got a decent number," said Cindy LeFleur, policy coordinator for the Columbia River Compact, made up of the Washington and Oregon fish and wildlife departments.

The Columbia and Snake rivers are closed to sport fishing in both states. So far, this year's run has been a disappointment. Forecasters initially anticipated as many as 254,000 fish, but more recent projections ran as low as 70,000.

Now, as numbers appear to be improving, state, federal and tribal officials in Washington, Oregon and Idaho are monitoring the run closely. The number of chinook that pass through Columbia and Snake fish ladders this weekend could have consequences for the sport-fishing industry, worth hundreds of millions to state economies.

"If we're lucky, we can make some decisions, but it's still pretty tight," said LeFleur from her offices in Vancouver, Wash. "I'm just hoping these numbers will stay up there — or climb. That's possible, considering we've had late runs before."

Scientists are unsure why numbers are down. In 2001, 437,000 fish were checked through Bonneville Dam, and their offspring should be returning this year.

Some environmentalists blame dams and low water flows for hindering the fish. About 10 percent of young salmon may get killed in the turbines that transform the flows into hydroelectricity.

With early indicators down, Idaho closed a 23-mile stretch of the Snake on Wednesday. Tribes with treaty rights to salmon agreed Tuesday to suspend all gill-net fishing, including for ceremonial and subsistence purposes.