Petro-Canada, Calgary, (NYSE: PCZ; Toronto: PCA) has raised its bid through subsidiary Nosara Holdings Ltd. for all shares of Canada Southern Petroleum Ltd., Calgary, (Toronto: CSW; Nasdaq: CSPLF) to US$11 in cash per share for a total deal value of approximately US$159.5 million. Petro-Canada had previously offered US$7.50 per Canada Southern share. Canadian Oil Sands Ltd., a subsidiary of Canadian Oil Sands Trust, Calgary, (Toronto: COS.UN) was the previous high bidder, offering US$9.75 per share in cash for a total deal value of US$146 million. Canada Southern has estimated gas reserves in the Arctic Island of 927 billion cubic feet equivalent. It also holds reserves in southern Yukon and northeastern British Columbia currently producing 6 million cubic feet per day.