March 5 (Reuters) - Canada’s main stock opened higher on Friday as energy stocks gained 2.8%, tracking higher crude prices, while data showing a surprise domestic trade surplus in January further lifted sentiment. * At 9:30 a.m. ET (14:30 GMT), the Toronto Stock Exchange’s S&P/TSX composite index was up 138.82 points, or 0.77%, at 18,264.54. (Reporting by Amal S in Bengaluru; Editing by Vinay Dwivedi)