Teacher shortages in secondary schools are at their highest since 2008, according to data compiled by the Post Primary Teachers Association (PPTA).
More than 3000 jobs were advertised last year, with data showing a steady increase in the number of vacancies over the last three years from a 2013 low.
The PPTA describes the secondary teacher shortage as "crisis point".
"There are vacancies in many subject areas and in many geographical areas," it says, adding recruitment is in decline and schools are losing teachers.
"Principals are considering the prospect of cancelling subjects for lack of trained and qualified secondary specialists."
In recent weeks, the problem has been described as a "nightmare", and a "potential disaster" in the long term.
PPTA president Jack Boyle said some principals would be in panic-mode trying to figure out how to staff their subject just days out from term starting.
"It's really tough for the principals and I don't envy them having to make some less than ideal choices," he said.
"Ultimately there are going to be some knock-on effects, if you haven't got a teacher to put in front of a classroom then they're going to be having to make the best of a bad bunch of choices."
PPTA president Jack Boyle says principals will be panicking to fill vacant teacher roles before the start of term. Photo / John Borren
The shortage could lead to an increase in class sizes, cuts to subjects, and other teachers filling the gaps often outside their specialist areas.
Children could lose out on one-to-one time as class sizes grow, adding stress to both pupils and teachers; others could see the subject they're passionate about scrapped or would be forced to use the correspondence school to keep studying if a teacher wasn't found for that subject.
"It's a fabulous learning resource, but it's really hard to try to mirror the value of having a highly trained and highly competent and passionate teacher in front of a classroom," Boyle said.
The teacher shortage wasn't restricted to Auckland, he said, although the city was a hotspot at the moment.
External factors - such as the high cost of a home - were major factors, Boyle said.
He called on the Government to focus on recruitment and retention of teachers, to make teaching "a first choice profession"; and said a "cross-partisan consensus" on increasing remuneration for teachers was needed in order to attract new graduates into teaching.
This morning, Labour's education spokesman Chris Hipkins blamed the Government, saying spending on teacher recruitment had sunk during National's time in office.
"National has ignored looming teacher shortages the entire time they've been in Government," he said.
"Their chickens are coming home to roost."
Labour Party education spokesman Chris Hipkins says National has failed to ensure an adequate supply of teachers. Photo / Marty Melville
Critical teaching shortages had grown, he said, as funding to programmes that helped recruit people into the profession had dropped.
"Since they took office, National has stripped over $6 million out of the TeachNZ programme, which aims to ensure an adequate supply of teachers in schools and early childhood services," Hipkins said, adding it was now half what it was when National took office.
"News that schools in Auckland are facing a teacher supply crisis comes as no surprise," he said.
"Quality teaching is the most critical component of a quality education. National has ignored the need to recruit and retain excellent new teachers for too long."
More than 600 teaching jobs were waiting to be filled across the country. Schools were struggling to arrange timetables and classes for the new year.
Nearly 200 of those vacancies were in crucial science and maths areas, which have become increasingly difficult to fill as science, engineering and maths university graduates get picked up by high-paying corporate and private sector companies.
Meanwhile, Auckland's "ridiculous" house prices have been blamed for escalating the teacher shortage in the country's largest city, forcing young teachers out.
Three young teachers in critical science jobs from Mt Albert Grammar in central Auckland fled the city at the end of the last school year, pointing the finger at the cost of buying a home for their decision to leave.
