Almost a third of Aberdeen primary schools started the new academic year without a permanent headteacher.
The 17 gaps – and another at a secondary school – are on top of dozens of classroom vacancies revealed by the Press and Journal last week.
Aberdeen City Council said it excluded them from stated shortages because the roles were filled by other teachers “acting up”.
The stop-gap arrangements increase the pressure on schools and underline the struggle facing authorities across the north and north east to recruit staff.
But education convener Angela Taylor said heads were not paid enough to attract top talent and vowed to raise the issue in talks with the Scottish government.
“There could be an issue regarding the salary differential between deputy head teachers and head teachers,” she said, putting the gap at about £4,000 a year.
She and council leader Jenny Laing will push for a more lucrative package when they meet Education Secretary John Swinney for talks next month.
Staff were going “over and above the call of duty” to cover the gaps left by deputies carrying out the duties of heads, she said.
The city’s secondary schools are short of 28 teachers – an average of just over two each – while the 47 primaries need another 53.
Hazlehead Academy has been forced to drop computer lessons for senior pupils after failing to replace staff who left a year ago.
Seven additional support needs teaching posts are also vacant – almost 6% of the required staff.
Councillor Alex Nicoll, the SNP’s education spokesman, said he would welcome stronger local efforts to reduce the number of acting heads.
But he said the only lasting solution was to increase pay to make senior roles more attractive.
“Over the years the differential for taking on the extra pressure and responsibility of becoming a head teacher has gone down,” he said.