There has been a boon in the number of teachers registered to teach Welsh or science in Wales. But the number of newly-trained entrants to the profession has fallen by 176 since 2002, to 1,542.
Unions welcomed the rising number of Welsh-language and science experts, but warned an overall drop in newly-qualified teachers could fuel a staffing crisis as national reforms of the curriculum for three to seven-year-olds and at 14-19 are rolled out.
According to the latest statistics from the General Teaching Council for Wales (GTCW), 506 teachers are now registered to teach second-language Welsh - 139 more than in 2004-5. First-language teachers able to work in Welsh-medium schools have gone up 42 to 266.
Just over 30 per cent more teachers were registered as having reached the induction standard for science subjects in 2004-5, compared with the previous year.
But Wales is still struggling to recruit professionals from ethnic-minority communities. Nearly 95 per cent of teachers in Wales are from white British backgrounds. Only 14 people from an ethnic-minority background or of mixed heritage were registered with the GTCW up to last August.
The GTCW figures for March 2006 also show there are 103 fewer headteachers registered in Wales than three years ago. But the number of serving heads holding the National Professional Qualification for Headship - a requirement for all first-time heads since September 2005 - has risen to 256, compared to a previous high of 247 in 2003 and a subsequent low of 197 in 2004.
Gruff Hughes, general secretary of Welsh-medium teaching union UCAC, welcomed the rise in Welsh-language experts but warned it was overshadowed by the fall in NQT numbers.
He said: "We have falling pupil numbers but also the start of exciting initiatives, such as the foundation phase and 14-19 learning pathways, that require more qualified teachers."
An external evaluation report on the pilot foundation phase found that results were best in schools using qualified teachers rather than non-teacher early-years staff.
Mr Hughes said union members were also meeting with the Assembly government to talk about a potential crisis in head recruitment.
Figures released at the end of last year showed that barely a third of NQTs training in Wales in 2004 found jobs in the country. New figures on the destinations of students completing initial teacher-training are due out later this month.
NQTs, particularly in the primary sector, have been struggling to find posts as pupil numbers decline. Cuts in funding have also been blamed for loss of posts.
However new government statistics show the number of full-time equivalent primary teachers working in maintained schools has risen for the first time in four years, to 14,018 in 2005-6 (compared with 13,474 the previous year).
Secondary teacher numbers in Wales peaked last year at 13,767, dropping to 13,592 in 2005-6.
Jane Davidson, minister for education, lifelong learning and skills, has announced 5 per cent cuts in teaching-training places for the past two years.