TORONTO (Reuters) - Hedge funds have raised their bets against Canadian silver-mining stocks, January short-selling data from a market regulator showed, while the miners’ shares and silver itself rose sharply due to buying by retail investors. A social media-driven buying spree lifted silver to an eight-year high on Monday, spurred by posts on the same Reddit message board behind last week’s frenzied buying of GameStop Corp and other shares. But the rally later cooled on doubts about the ability of retail traders to move prices in a bigger, more liquid commodities market.