Fisheries and Oceans Canada has announced a limited recreational fishery on the lower Fraser River starting Friday.

The first commercial sockeye salmon fishery will open Saturday night near Campbell River and stay open all weekend.

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Fisheries and Oceans Canada had been forecasting an abundant return of 23 million salmon to the Fraser River, but early estimates have been "less than anticipated."

In a technical briefing, Fisheries and Oceans said there is still huge uncertainty over the size of the run, which was estimated at 23 million fish pre-season, but could be as low as seven million.

In 2010, the return was an estimated 30 million fish.

Fisheries and Oceans also said Fraser River water temperatures could end up affecting the run.

Temperatures in the Fraser have been climbing. On July 2,8 the temperature of the water was estimated at 17.8 C, but was forecast to go as high as 20.5 C.

Sustained water temperatures in this range can cause severe stress to migrating sockeye and could lead to severe en-route mortality, said Fisheries and Oceans in its latest assessment.

Caution warranted

Officials have good reason to be cautious when estimating sockeye salmon run sizes in B.C.

Determination

Sockeye salmon fight their way up the Adams River during a previous run.

In 2009, Fisheries and Oceans Canada predicted a huge return of 10 million fish to the Fraser River. When only a million showed up, the apparent collapse of that fishery prompted a $26 million federal inquiry.

In 1995, the returns in the area were so low there were fears the fishery was collapsing.

The sockeye salmon season begins in mid-July and lasts until mid-September with the bulk of the run beginning to arrive in B.C.rivers in early to mid-August.

With files from the CBC's Richard Zussman and Tina Lovgreen