Results from Police Strike Force Vulcan, an initiative run from December until the end of March, showed emergency services dealt with 719 fires over the four-month stretch.
The figure was up slightly on the same period in 2013-14 but down on the 1037 fires in 2011-12 and the 972 fires in 2012-13. However, the number of bushfire-related charges jumped from 33 in 2013-14 to 53 in 2014-15.
Alarmingly, police said 36 juvenile offenders had been detected this past bushfire season. The Strike Force Vulcan team consisted of uniformed officers from each WA Police district and officers from State Crime, led by detectives from Arson Squad.
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READ NOWThe police worked in partnership with the Department of Fire and Emergency Services and the Department of Parks and Wildlife and also received crucial assistance from the public.
Arson Squad officer-in-charge Detective Senior Sergeant Craig White said significant results had been achieved during the four-month operation.
He described the number of juvenile offenders as "unusually high".
"It is the second year in a row we have been dealing with boys aged 10-17, usually in groups," Sgt White said.
"This is considered both nationally and internationally to be an unusually high number, prompting us to set up a new research project, to be developed in conjunction with Edith Cowan University, to look at what triggers this type of behaviour," he said.
Emergency Services Minister Joe Francis said the persistently high level of arson highlighted the difficulties in both deterring and detecting offenders, but said it did not diminish the progress made by Strike Force Vulcan over the past four years.
"Some significant achievements have been made over this fire season in detecting and charging people with arson offences because of the great work Vulcan has done," Mr Francis said.