Damaging mould has been found on a world class whale bone collection stored by the national museum, Te Papa.
Te Papa is now investigating how over 400 bones became mouldy – that's more than 20 per cent of the collection.
It comes as the museum prepares to announce its third round of job cuts to its curator staff in five years.
Dozens of experts from around the world have written to the Prime Minister concerned the museum can't adequately care for its collections.
Anton van Heldon looked after the unique and extensive whale collection for 24 years until a recent restructuring by Te Papa.
"Very literally my blood sweat and tears went into that collection," he says.
He says he was heartbroken to hear the bones, which contributed to Te Papa's highly successful Tahora exhibition, were damaged.
Whale bones are oily which is why they are vulnerable to mould, but experts say the extent of the problem is unacceptable.
"If this had been caught earlier on it might be a different story. But now they're facing… much more work to deal with this issue," says Diana Coop, the president of NZ Conservators of Cultural Material.
There have been several restructures at Te Papa recently, including ones in 2013 and 2015. The latest proposal could see up to 25 jobs cut – halving the number of conservators and again cutting collection roles.
Te Papa says "caring for the collections is the core of what we do as a museum and that will never change," but it couldn’t comment consultations on the proposals were underway.
More than 30 experts are concerned though. Trevor Worthy is one palaeontologist who has written to the Prime Minister.
"It's absolutely not good enough because each of these collections needs specific expertise," he says.
The Government says it's sought reassurances from Te Papa that collections will be effectively and properly managed.
Meanwhile Te Papa says it’s working hard to ensure the whale bones are repaired.
"The usual kind of treatment we'd use is UV treatment then an ethanol treatment but our primary concern is the specimens are not degraded," says Head of Science Susan Waugh.