A shortage of teachers in New Zealand's largest city is continuing to cause major stress for school leaders.

Principals throughout Auckland are expressing concerns over the diminishing number and quality of teaching staff throughout the city.

Pakuranga College principal Michael Williams says hiring staff for 2017 was the hardest he has experienced.

"I had to recruit around 20 staff and it took some hard yards and seriously stressful nights to get those teachers," he says.

"We've had to resort to a lot of arm-twisting of retired teachers getting back into the classroom, and in those critical areas we've had to be a lot more creative and encourage staff to take on other subjects."

Manurewa East School principal Phil Palfrey also had a "terribly difficult job" getting teaching staff.

"I had about eight teachers leave for various reasons at the end of last year and to replace them was horrendous and extremely expensive," he says.

"I had to spend days and days in my break making sure I had staff. I've never had to do that before.

"I recruited two teachers from Christchurch and used an agency for two others. All up it would have cost around $10,000."

Why is Auckland experiencing a teacher shortage?

Williams says the teacher shortage is being exacerbated by Auckland's housing problems.

"If you're on a teacher's salary in Auckland, you can't survive," he says.

"If you're a young couple the reality is you might be able to afford a house, if you're lucky, but if you want to have a house and a family then forget it. The two in Auckland pretty much can't happen.

"It means all of our young people are leaving Auckland with no hope of ever getting back, and on the flip side no one is coming to Auckland."

NZ Principals' Federation president Whetu Cormick​ says he's also hearing that the quality of applicants for teaching positions is declining.

"We're hearing anecdotally from principals that some of these teachers aren't qualified or suitable for their positions," he says.

Howick College principal Iva Ropati has felt the strain of the problem.

"We are a decile 8 school, within a desirable community and location, but from amongst 20 applications we would struggle to shortlist three people," he says.

"We're having to work harder and a lot more creatively in order to get the right person for our school."

What is the Ministry of Education doing to help?

The ministry's acting deputy secretary for early learning and student achievement, Karl Le Quesne, says it has been listening to schools' concerns.

"We're continuing to work hard at supporting those Auckland schools and their principals who are finding it difficult to recruit staff, particularly in key subject areas," he says.

"As the supply situation has changed over the last 12-18 months we have shared our data and information with principals and sector groups, identifying issues and potential solutions as they see them."

Last August, Education Minister Hekia Parata announced that $9 million would be invested over the next four years to address teacher supply pressures.

Several initiatives were introduced such as an extra 100 Teach NZ scholarships per year for science, technology and maths (STM) subjects and the Beginning Teachers Project, set up in collaboration with Auckland Primary Principals' Association.

The Beginning Teachers Project is a two-year project which saw 40 new primary teachers employed in schools in Auckland, with the ministry paying $24,000 to each participating school to cover the first two terms of their employment.

Howick Primary School principal Leyette Callister​ says the project shows a positive move by the ministry to be more proactive and support staffing supply in Auckland.

"It's like finally the ministry is listening. If I didn't have that teacher now, then at the middle of the year when I'm looking for one there are none, and that's when it gets really tricky."

Are overseas recruitment drives the best solution?

In addition, the ministry is working on overseas recruitment drives such as the Bring the Kiwi Home campaign, aimed at encouraging NZ teachers working overseas to return to teach in this country.

"Although it's still early days, we're beginning to see signs that non-NZ teachers are seriously considering coming here to work and that NZ teachers are looking to return," Le Quesne says.

"Fifty-nine UK teachers moved to NZ in 2016. This trend is likely to continue in 2017 with four UK teachers already recruited by schools for 2017."

Cormick says overseas recruitment schemes may be a solution, but candidates need to be qualified to teach in a NZ context.

"We want NZ-qualified teachers, whether they be foreign or not, they need to be able to teach within our contexts," he says.

Principal of Elm Park School, Trish Plowright​, says hiring overseas teachers requires a lot more work as they need to be treated like a beginning teacher.

"If they put them through a refresher course that they didn't have to pay megabucks for then it might be more suitable. There should be something that you actually have to pass to teach here as you are responsible for children," she says.

Ropati adds: "If the ministry go out there and wave the flag, they've got to be upfront in terms of the calibre of teachers they need and not just make it open slather."

Should there be an Auckland teachers' incentive?

Cormick believes the best way to address the teacher shortage is to incentivise teachers into difficult-to-staff areas.

"Auckland is not the only province scrambling to find teachers. I'm hearing from principals in cities like Queenstown and Wellington that there are teacher shortages too.

"We're suggesting the ministry should be looking at providing incentives for these key areas because the main issues are the cost of living and travel."

Williams agrees, saying: "I know it's not popular but the simple solution is to pay the poor teachers some more money so they can survive.

"The scary part is we can't really see it getting any better. So next year I think will be even worse than this, unless the ministry takes a serious look at some sort of differential."

Le Quesne says any changes to pay and conditions are negotiated as part of the well-established bargaining process and an Auckland allowance has not been proposed in that context.​