Low pay, big workloads and growing levels of abuse are among factors discouraging people from teaching, according to Post Primary Teachers' Association representatives.
Young people are reluctant to enter the profession, as much of the current work force approaches retirement age, representatives say.
A PPTA report has highlighted nationwide staffing issues including difficulty finding maths and science teachers and staff leaving for jobs in other industries or to retire. The report follows a term one survey of secondary and composite school principals about their staffing situations.
PPTA Northland central regional chairman Micky Nogher said people were reluctant to move into teaching because they could get better salaries elsewhere. The workload for teachers was also "phenomenal" and increasing, he said.
Mr Nogher said highly trained and experienced staff were also leaving the profession as they couldn't endure the growing levels of verbal and physical abuse they faced on a daily basis.
PPTA chairman for the Wanganui and Manawatu area Alan Carson said many teachers within the region were nearing retirement age and young people weren't keen to enter the profession.
"They're not enthused about becoming teachers. They see teachers as working far too hard for the money they're getting."
The vocation factor that attracted teachers 30 or 40 years ago had largely gone, he said.
According to the Ministry of Education, teachers over 60 represented 7 per cent of the teacher workforce in 2004 compared to 13 per cent in 2012, the most recent year for which ministry data was available.
Graham Stoop, deputy secretary, student achievement and investing in educational support said the age bracket with the highest number of teachers was 50-54.
Teachers under 30 years of age made up 14 per cent of the workforce in 2004 compared to 11 per cent in 2012.
PPTA Hawke's Bay chairman Julian Lumbreras said many baby boomer teachers in Hawke's Bay were retiring.
One local school had nine jobs advertised in the Education Gazette and he understood six or seven of them were following retirements.
He believed teaching was not a priority for most students leaving school, who were increasingly choosing careers based on salary packages.
The balance between workload and pay was also a big factor in job choice.
PPTA Bay of Plenty chairwoman Rae Brown said local schools reported staff were near retirement age and they expected to have difficulty replacing them.
Rotorua's John Paul College principal Patrick Walsh said the school had a number of teachers over 65.
Young teachers were coming through but he wasn't sure they were in the right subject areas.
There needed to be more scholarship and incentives for people to study things such as chemistry and physics, he said.
The PPTA Secondary Staff Report showed advertised jobs were increasing and the mean number of applicants per position was declining. The proportion leaving to go to other jobs outside teaching had also increased.
Those leaving for 'other reasons' such as retirement, accounted for the largest proportion of leavers.
Principals expressed reservations about the impacts of pending retirements on their schools. They were, in general, less optimistic about retaining teachers and more pessimistic about recruiting.
Principals frequently mention maths, Te Reo, sciences and technology as hard to staff subjects.
There was a jump in teachers being used outside of their specialist area because specialists could not be found, according to the report.
Around one in nine schools had to cancel classes or transfer to a form of distance learning because a suitable specialist teacher could not be found, the report said.
NZME kf er