Wales is training too many primary teachers and not enough Welsh-medium specialists, according to a report recommending a full review of the country's teacher-training sector.
It suggests that more work-based training and flexible courses could help plug shortages in some secondary subjects, such as maths and science, and allow more opportunities for career changers to join the profession.
And with Welsh children unlikely to encounter a male teacher until Year 3 or beyond, it recommends setting targets for recruiting more men to primary.
But redressing the primary-secondary imbalance could mean closing some of the eight university departments currently offering teacher-training courses, it warns.
The study, commissioned by the Welsh Assembly government, was generally welcomed by the teaching unions. But Gethin Lewis, general secretary of the National Union of Teachers Cymru, warned against any assumption that fewer primary teachers will be needed.
He wants more teachers - rather than "higher level" teaching assistants - employed to meet the workforce agreement requirement that all teachers have 10 per cent planning, preparation and assessment time from September 2005.
Jane Davidson, education and lifelong learning minister, said it was important to look at where investment was needed.
"We need to make sure career structures are in place for people who want to get into teaching," she told the Assembly's education committee.
Officially, Wales has fewer unfilled teaching posts - 0.4 per cent - than any English region. It also trains a disproportionate number of teachers for its size, 7 per cent of the national total rather than 6 per cent.
But colleges are being asked to recruit the same numbers of primary and secondary trainees (1,150 and 1,320 respectively) this year as last, despite falling rolls in primary schools leading to redundancies in parts of Wales. Yet only three maths graduates trained in Welsh this year, highlighting the shortages in some secondary subjects, particularly of Welsh-medium teachers.
Anna Brychan, director of the National Association of Head Teachers Cymru, said her union would welcome any initiative that helped meet the growing need for Welsh-medium teachers.
"That's one of the areas where we have recruitment problems."
Mike Haines, the report's author, says expanding the Graduate Teacher Programme could help address concerns about both recruitment and retention.
The GTP pays trainees pound;13,000 a year to qualify "on the job" in schools. While one in 10 students on university courses drops out, 97 per cent of GTP candidates complete their training. Wales may need a home-grown model for planning how many teachers it needs in future to take account of its distinctive education policies, as well as Welsh-medium issues.
However, there is no convincing case for divorcing the Welsh system from England, according to Mr Haines. Care needs to be taken to ensure teachers'
qualifications are accepted in both countries, given that around a quarter of Welsh trainees come from England, and between a quarter and a third of those qualifying in Wales move to England to teach.
Geraint Davies, secretary of the National Association of Schoolmasters Union of Women Teachers Cymru, said more needed to be done to ensure primary teacher graduates were not left without jobs and lost from the profession.
Dr Carl Peters, chair of UCET Wales, which represents training providers, said greater collaboration between colleges should avoid mergers or closures.