The chinook salmon sport fishery on the Yukon River is being restricted to zero retention Thursday at midnight, due to a below-average return of chinook.

A variation order has been given which will reduce the retention number to zero, which means that although anglers will still be able to catch chinook, they will have to release them.

The commercial and domestic fisheries have been completely closed this season. However, Department of Fisheries and Oceans area director Frank Quinn said the aboriginal food fishery will remain open.

'We don't anticipate this having any impact on the first nations fishery at this point,' Quinn said this morning. 'If the run gets stronger, there is a chance that the variation order could be changed later on this season, but we don't know yet.'

Management officials were initially expecting a return of 45,000 fish to the Yukon-Alaska border on the Yukon River, which would have provided sufficient spawning numbers and allowed for a full aboriginal, commercial, sport and domestic fishery.

That forecast has experienced a significant decrease, and the total run is now expected to be between 21,000 and 31,000 salmon.

More severe restrictions have been in place in the past, with the sport and aboriginal fisheries both being restricted for some seasons.

'Something could still happen with the sport fishery this summer, but we won't know until the fish arrive,' Quinn said. 'The return is a little different each year. Next year could be a great year, but it's far too early to tell.'

So far, approximately 1,000 salmon have been harvested at the aboriginal fishery this year.

Records show the aboriginal fishery harvested 5,557 chinook last year; the commercial fishery took 2,332; the sport fishery took in 606 and the domestic fishery received 63.

Quinn was unsure just how many anglers have licenses, since they are sold by vendors throughout the territory and official numbers are not tabulated until the end of the year.

He added that the first chinook were expected to pass through the Whitehorse ladder this week, but there have yet to be any spotted.

Three test fisheries upriver of Dawson City have been trying to determine the strength of the run in recent weeks, and Quinn said officials have determined the strength of the run just isn't there.

A variety of factors could be responsible for that, including high water, cooler than normal ocean temperatures, and availability of food.

Official tallies to date show that 124,622 chinook have passed by the Pilot Station Sonar on the Alaska side near the mouth of the Yukon.

That's down 30,000 from the 10-year average, and 44,000 from the same time last year.