Sydney's pitiful list...
Air Canada
Halifax (6 times daily)
Toronto (daily seasonal)
Westjet
Toronto (daily seasonal)
Air Ste Pierre
Saint Pierre et Miquelon (seasonal twice per week)
Charters
Canadian North
Provincial Airlines
Maritime Air Charters
Atlantic Charters
Skylink Express (cargo)
And to show the effect competition has had at the airport, in 2005 when Air Canada had their monopoly 91,709 used the airport. 5 years later (the second year Westjet started seasonal service) it was 137,946.
Source Last year it was 139,000.
Westjet's effect vs Sunwing's
2005 (AC only) 91709
2006 (AC, Sunwing seasonal Toronto and vacation Holguin) 99819
2007 (AC, Sunwing seasonal Toronto and vacation Holguin) 105699
2008 (AC, Sunwing seasonal Toronto and vacation Holguin) 110709
2009 (AC, Westjet seasonal Toronto, Sunwing service stopped) 120898
2010 (AC, Westjet seasonal Toronto) 137946
2011 (AC, Westjet seasonal Toronto) ~139000