There's more to Te Papa than exhibitions and historical items on display. At its Tory St facility is stored birds and bones, fish, and more to use for scientific research and testing.

Millions of irreplaceable and invaluable natural history specimens could be lost if Te Papa Tongarewa goes ahead with the its proposed job cuts, scientists fear.

A document leaked to media on Monday revealed the national museum had proposed a staffing restructure that could cut up to 25 positions from its permanent work force, with 50 jobs in total affected.

In a statement, Te Papa spokesperson Kate Camp said the museum wanted to modernise its approach in caring for and accessing the collections as a result of changing technology.

MUSEUM OF NEW ZEALAND TE PAPA Leaked documents reveal Te Papa is proposing another reshuffle, just three years after its prior restructure.

"Over the last 20 years, Te Papa has changed to stay at the forefront of museums. To do our job we evolve and adapt, like many organisations in New Zealand," she said in a statement

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"The changes we are proposing to how we work are about responding to changes to society and technology, and being in the right shape for the future."

Supplied Te Papa chief executive Geraint Martin said he had no plans to reshuffle when he took his new post last year.

But one department at risk of downsizing was the collections research, an area that was already undervalued, according to former curator of Whanganui Regional Museum's Natural History, Dr Michael Dickison.

"Millions of natural history specimens collected over hundreds of years are a library and treasure house of our biodiversity," he said.

"Many are specimens for things that are now extinct, so literally irreplaceable.

ROSS GIBLIN/ STUFF Dr Mike Rudge, left, and Marine Scientist Lionel Carter are both concerned at Te Papa's new proposed restructure that could harm collections.

"We have a responsibility in museums to be the custodians - we want these collections to last at least another 100 to 200 years."

Over the last 10 years, Te Papa has had two major restructures. In 2012, 31 jobs were lost in a restructure that cost Te Papa $1.6 million and the number of collection managers was reduced by 42 per cent.

When chief executive Geraint Martin took his post in July last year, he told staff that he had no immediate plans for changes. Camp said the museum was in "good financial health" and the proposal was only to seek feedback from staff.

Dickison worked at Te Papa when it was formerly the National Museum. He said the collections research department, which employed about 85 fulltime employees, should be increasing rather decreasing.

"Decisions that are made now could lead to huge losses and expertise. In a hundred years, curators could be looking back at this time, because they will be, and cursing that time in 2018 when the museum let a bunch of people go and lost a whole lot of expertise. There will be a huge gap in the cataloguing and creation of those collections," he said.

"We have to be thinking very long term when we are entrusted with being custodian of these collections for centuries."

It was only in the last 10 years that scientists discovered they could scratch tiny fragments of DNA from museum collections, even in things that had been preserved in alcohol.

This breakthrough, Dickison said, could help humans learn about extinct species and find out what they ate, how they reproduced, their sex and their age.

"We've discovered new species of animals from museum collections that have been extinct for hundreds of years just by looking at this DNA. he said.

"A museum is the one place that keeps and looks after biological specimens for such a long time."

Former manager of Collection Services at Te Papa Tongarewa Michael Rudge said the museum's reputation would be tainted if it went ahead with stripping more collections employees. Many collection items were bequeathed to the museum by families and trusts.

"People expect their materials, often their families' collections, to be looked after and if you don't have collection managers and conservators who know how to look after things, Te Papa's reputation for being the place to put those things is going to suffer," he warned.

The other departments that are likely to be affected are Audience and Insight, Museum and Commercial Services, Finance and Operations, and Strategy and Performance.