A charity that saves stranded whales and dolphins has had invaluable equipment earmarked for Tauranga and the Bay of Plenty region stolen.

A trailer belonging to Project Jonah, which was to be used in stranding emergencies in the Bay this summer, was taken from a rooftop car park in Auckland on Friday.

Rescuers work to save two whales that became stranded on Papamoa Beach in October 2011.

Project Jonah is a registered charity that helps marine mammals, including dolphins and whales. The stolen trailer is one of four used to transport equipment to sites around New Zealand during whale stranding emergencies.

It had not yet been insured as the organisation was in the process of negotiating an insurance policy.

CEO Kimberly Muncaster says the theft is a devastating loss to the charity, which relies solely on donations.

'We're just devastated; this is a major setback.

'This is a double blow as we're just coming into the stranding season and need fully-equipped rescue trailers around the country so we can respond quickly to stranding emergencies."

Project Jonah relies on goodwill, donations and volunteers to be able to continue its work, "doing a lot with a little,” says Kimberly.

"We're a small charity and we struggle to do the work we do with the money we have."

She says the trailer was earmarked for Tauranga to cover the Bay of Plenty region.

There were a number of whale strandings in the Bay of Plenty in 2011, including two Gray's beaked whales on Papamoa Beach and one pygmy sperm whale on Ohope beach.