There are fears of a brain drain in Tasmania, with warnings that half the state’s CSIRO staff face the sack.

The Community and Public Sector Union says six to 10 of the 13 workers at CSIRO's Sandy Bay campus could be lost.

The jobs are at risk from changes linked to the federal budget, and are in addition to 31 jobs already cut in a restructure and 18 positions abolished from marine and atmospheric research.

CSIRO Staff Association organiser Paul Girdler says the exact number of job losses should be clarified in the next few weeks.

“Once that's determined, CSIRO will go through a process of determining who it is that's to go,” he told the ABC.

This round of science job cuts come from the forestry sector, which employs 54 CSIRO staff across Hobart, Canberra, Brisbane and Perth.

“Obviously we're very concerned for our members in this situation,” Mr Girdler said.

“A lot of them have families, mortgages, etcetera. It's a terrible position to be placed in.”

CSIRO has released a statement saying that climate impact research will be retained, but there are duties outside of this field for staff at the Sandy Bay lab.

“CSIRO will be retaining capability in forest sciences that can contribute to greenhouse gas mitigation and climate adaptation strategies, as well as science focused on water, fire and environmental management relating to trees in landscapes,” the statement reads.

“Some of which will be located at our Sandy Bay laboratory.”

“This capability, along with the Forest Genetics and Improvement staff retained in Canberra will form a nucleus from which we can grow our efforts in the future, should industry and government be able to increase its co-investment,” the statement added.

The Federal Government cut $110 million from CSIRO's budget in the May federal budget.

The CPSU says there have now been 67 job losses from CSIRO science facilities in Hobart this year.

There are estimates that about 700 jobs will be lost nationwide this financial year; 420 due to budget cuts and 280 from restructuring.