Sticky-fingered thieves made off with almost 30 million Canadian dollars (US$30.4 million) worth of maple syrup from a strategic reserve in rural Quebec. David George-Cosh reports on the News Hub. Photo: AP.

TORONTO—Sticky-fingered thieves made off with as much as 30 million Canadian dollars (US$30.4 million) worth of maple syrup from a little-known strategic reserve in rural Quebec—leaving authorities to investigate just how much is missing and where it has gone.

The Federation of Quebec Maple Syrup Producers said late Thursday that during a routine inventory check at a facility that stores some 10 million pounds of syrup, inspectors discovered barrels had been emptied and reported "missing a large quantity of maple syrup."

Quebec produces about 75% of the world's maple syrup. Despite the theft, the federation said there would be no immediate impact on world-wide syrup supply.

The facility holds about a fifth of the province's total quantity of unsold supply, stored each year to protect producers' from the ups and downs of global supply and demand. Late Friday, police and an official from the federation said that not all of the syrup stored at the warehouse—in St-Louis-de-Blandford, about 100 miles northeast of Montreal—was missing. But they couldn't give an accurate estimate of damages.

"We're trying to value how much was missing," said Anne-Marie Granger Godbout, executive director of the federation. "Some barrels are full, some are empty." Quebec police are on the case, said spokesman Sgt. Ronald McInnis. Late Friday, two investigators were still at the facility, collecting evidence, he said.

The federation says it currently sells one pound of Quebec's maple syrup to distributors and food processors for C$2.86, though it can retail for much more at home and abroad. Ms. Granger Godbout said she suspects most of the stolen syrup could already have made its way to Europe or to the U.S., which is the biggest importer of Quebec output.

Though strategic reserves are typically used to cushion petroleum markets, Quebec has kept a supply of unsold syrup for more than a decade, to be drawn on if supply of the quintessential Canadian staple falls because of poor yields, or higher-than-expected demand. From February to about mid-April, about 7,400 Quebec farmers tap their maple trees and boil sap in mostly small-scale so-called sugar shacks. They evaporate the goop into several closely regulated grades of syrup—extra light, light, medium and dark.

But sometimes the weather doesn't cooperate, causing shortages. Quebec syrup makers started squirreling away a cushion in 2000. They had to tap the reserves each year from 2005 to 2008. In 2008 and 2009, Quebec ran the reserve dry. Since then, producers have been slowly building it back up, and it now holds about 50 million pounds, up from 37 million pounds last year, said Ms. Granger Godbout.

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