* Air Canada June load factor a record 85.6 pct
* WestJet load rises to 79 pct
* WestJet says bookings for July, August "remain strong"
* Porter June load factor dips, says outlook bright
TORONTO, July 5 (Reuters) - Canada's dominant airlines, Air Canada and WestJet Airlines Ltd, flew fuller planes in June, while smaller regional carrier Porter Airlines reported slightly emptier flights than a year earlier.
Air Canada, the country's biggest carrier, said on Thursday that its June load factor, or the percentage of available seats filled with paying customers, rose to a record 85.6 percent from 84.2 percent in the same month last year.
Traffic increased 1.5 percent as capacity, measured in available seat miles, declined 0.1 percent.
"This record load factor result for the month also demonstrates the effectiveness of our strategy to manage capacity to ensure high efficiency," Chief Executive Calin Rovinescu said in a statement.
The load factor on Atlantic routes increased to 89.2 percent from 86.3 percent, while Pacific routes remained strong, with the load factor notching higher to 93 percent from 92.6 percent.
Calgary-based WestJet said its June load factor rose to 79 percent from 75.7 percent a year earlier, as traffic increased 6.7 percent and capacity grew just 2.3 percent.
WestJet also said reservations remain strong for the July and Augusts, the two busiest months of the year for Canadian airlines.
WestJet's second-quarter load factor rose to a record 81.6 percent from 78.1 percent in the year-before period. Quarterly traffic increased 7.4 percent as capacity rose just 2.9 percent.
"With WestJet indicating that forward bookings remain strong for July and August, we expect yields to support its outlook for slightly moderated growth relative to the 6 percent growth rate in Q1," said National Bank Financial analyst Cameron Doerksen in a note.
WestJet, which launched service to New York's La Guardia Airport in June, also said it will increase weekday flights to La Guardia to eight from seven starting July 12.
Privately-owned Canadian regional carrier Porter Airlines also reported numbers for June on Thursday and said its load factor fell to 62 percent from 64.6 percent, as traffic rose 4.1 percent and capacity climbed 8.5 percent.
"Numbers for June, although slightly less than in 2011, met our expectations," said Chief Executive Robert Deluce, noting that Porter's traffic was boosted in June 2011 by a brief strike at Air Canada, as sales and customer service agents walked off the job.
Porter said its second-quarter load factor edged up to 61.5 percent from 59.7 percent in the same period last year, as traffic increased 17.5 percent and capacity rose 14 percent.
"Our second-quarter and year-to-date numbers made gains and the outlook for the full year continues to be good," Deluce said.
WestJet shares rose as high as C$16.98 on the Toronto Stock Exchange on Thursday morning, their highest level in four years, before edging down to close at C$16.85, a gain of 13 Canadian cents.
Shares of Air Canada, which announced traffic data after markets closed, ended at 99 Canadian cents on the TSX, down 2 Canadian cents.