The vast majority of Scottish councils are increasingly struggling to recruit supply teachers, a survey by TESS has revealed.
Of the 25 local authorities that responded, 23 said there was a shortage of supply teachers in their area, with one saying that the situation had reached "crisis point". Councils also reported wider concerns around recruitment and signs of a teacher shortage after years of high unemployment in the profession.
Figures published by the Scottish government earlier this week showed that the number of teachers in the country had dropped slightly, from 51,253 in 2010 to 51,078 this year, and the proportion of post-probationer teachers in employment had risen from 75 per cent to 79 per cent in the past year.
John Stodter, general secretary of the Association of Directors of Education in Scotland (Ades), said that his members were concerned about the availability of supply teachers and about recruitment more generally.
"There are difficulties securing supply across the country and it has been getting worse since the summer break," he said. "There is also a general difficulty about recruiting for promoted posts and headteachers across the country. There are fewer people actually applying."
Mr Stodter said that the shortage in supply staff was largely due to teachers managing to secure permanent or longer-term posts and therefore being unavailable.
Greg Dempster, general secretary of the Association of Headteachers and Deputes in Scotland (AHDS), said that school leaders were having serious problems in finding cover and the time spent on this and providing cover took them away from their job of leading schools.
Headteacher recruitment had also become more difficult, he added. "It used to be something that you heard of in the context of very rural authorities but it is no longer restricted to that sort of concept," he said.
Joint headships and acting headships were two of the solutions local authorities were using to mitigate this, Mr Dempster said. Although many factors were contributing to senior teachers being put off from going for headship, a major deterrent was the relatively small pay rise they could expect, he added.
Councils responding to the TESS survey cited a number of reasons for the shortage of supply teachers, including lower overall teacher numbers, changes to short-term supply pay and increased demand for supply staff because of sickness and maternity leave.
Since 2011, a new deal between unions and the government has meant that supply teachers have to work for five consecutive days for a salary of pound;78 a day before their pay rises to pound;145. The agreement was met with widespread anger among teachers but subsequent attempts to negotiate a better deal for supply staff with local authorities body Cosla have so far ended in stalemate.
Laurence Findlay, head of schools at Moray Council, said the supply situation in his area was now "at crisis point, with a real risk to pupils' education and to our ability to keep our schools open and fully staffed".
He said that it had reached the point where council staff might have to be deployed to cover supply teaching shifts.
"Permanent officers within my section should be aware that they may be called upon at very short notice to clear their planners and report to a school for duty due to the current exigencies of the service," he said.
Of the local authorities that responded, only two - Edinburgh and Dumfries and Galloway - said they had no issues around finding supply staff. But many urban authorities that used to find recruiting supply teachers relatively easy reported the situation getting worse.
A spokeswoman for Glasgow City Council said: "There has certainly been an increase on unfilled (supply) posts in the last four weeks. We continue to fill long-term posts much easier than short-term posts."
Meanwhile, a spokesman for North Lanarkshire Council said that the authority was finding it difficult to recruit supply staff "for the first time".
"It would appear to be more acute in the denominational primary and in subjects such as sciences, drama, home economics and social subjects," he said.
A spokesman for Inverclyde said the lack of supply staff was causing "a disruption to the continuity of teaching and learning". Fife Council told TESS it was having a "significant impact on headteachers, depute headteachers and principal teachers".
This is not the first indication of a teacher shortage. In the autumn, TESS revealed that Aberdeenshire Council was looking to recruit teachers from Canada and the Republic of Ireland, and in the summer it was reported that Aberdeen City Council was offering financial incentives for teachers willing to relocate to the area.
A Scottish government spokesperson said: "The latest figures show that our teaching workforce is now stable after inheriting an unsustainable target on teacher numbers that led to increased unemployment. The Scottish government took steps to manage the supply side of the profession and we have the lowest level of teacher unemployment across the UK."
The spokesperson added: "The education secretary will also make a further announcement on more teacher training opportunities in the coming months."