As National Science Week draws to a close, the Government has started the build-up to its pound;20 million campaign to make the subject more attractive to pupils.
But the Association for Science Education said that the pressure on science teachers because of unfilled vacancies and the dearth of supply staff threatened to disrupt Science Year events. Daniel Sandford Smith, the association's curriculum support director, said: "We are concerned about whether science teachers will have the time to carry out activities for Science Year.
"There is very little slack in the system because of teacher shortages to allow staff to take time out."
A TESSecondary Heads Association survey published earlier this month revealed 375 science vacancies in 876 secondary schools, topped only by maths vacancies. Specialist supply cover is increasingly difficult to find. One Kent school has offered to pay more than pound;0,000 a term for a science supply teacher.
Physics specialists are particularly in demand. Some schools have no physics teacher, the subject being taught by chemists or biologists.
The association said there was also concern about cover for science teachers who will be out of the classroom during the summer term to receive training for the key stage 3 science pilot. It and the Institute for Physics have been trawling universities offering bursaries to physics graduates to entice them into teacher training.
A survey of the students found pay was seen as the main drawback to a teaching career. A spokesman for the Department for Education and Employment said training salaries and "golden hellos" were beginning to have an impact with applications to science teacher-training courses up by between a quarter and a third on this time last year.
A report published this week by the House of Lords Science and Technology committee has called for extra help for science teachers' professional development.