Wellington: A team of New Zealand scientists sifting through a slab of frozen leopard seal droppings have found a USB stick containing photos of frolicking sea lions.

The droppings, known scientifically as "scat", had been stored in a freezer for about a year and were being defrosted during research on the fish-eating mammals.

They were originally collected in November 2017 by a vet sent to check on a sick leopard seal on Oreti Beach on the southern tip of New Zealand's South Island.

"Concealed deep inside the scat was a USB stick," the National Institute of Water and Atmospheric Research (NIWA) said in a statement.

The memory stick was in reasonably good condition considering where it had come from, and after being left to dry out for a few weeks it was placed in a computer to reveal its secrets.

It contained photos of sea lions in a bay and a video of a mother sea lion and cub frolicking in the shallows.

The only clue to who might have taken them is the nose of a blue kayak.

"If they're yours and you want the USB stick back, it comes with a price. The leopard seal researchers would like some more leopard seal scat please," NIWA said.