A check for invasive aquatic pests around Auckland's Westhaven Marina has been postponed after the dive team happened upon a visiting leopard seal.
The bulky adult female has been hanging around the Hauraki Gulf since July, and lately has been spotted around the Waitemata Harbour, popping up in Orakei and Lucas Creek, as well as Westhaven.
The National Institute of Water and Atmosphere (Niwa) Auckland marine biosecurity team had planned to do a surveillance dive for the Ministry for Primary Industries, but have been mindful of hopping into the water while the big animal is around.
Leopard seals, typically weighing hundreds of kilograms and measuring several metres as adults, are normally found along the edge of the Antarctic pack ice but in winter, young animals move throughout the Southern Ocean and occasionally visit New Zealand.
They've been known to be aggressive when threatened, and can move surprisingly quickly on land and can seriously injure people or animals who approach it.
Department of Conservation officers have been closely monitoring the seal, and urge people to stay at least 20m away, and not to disturb it or try to feed it.
Niwa marine ecology technician Andrew Miller said when the dive had first been delayed, in June, DOC officers had expected the seal would have cleared off by now.
"But certainly, from communication last week, it's still around.
"I know that, very occasionally, you do get vagrant leopard seals coming up this far, but this one has been particularly persistent, and quite happy hanging around in the Waitemata and surrounding areas."
Miller was well aware of them from his previous job with the British Antarctic Survey, which, in a rare tragedy in 2003, lost young marine biologist Kirsty Brown to a leopard seal that dragged her underwater while she was snorkelling.
"It does strike a raw nerve, particularly, with me because I've had that experience with them in the past," he said.
"So I do know quite a lot about them and I give them healthy respect."
Miller noted this seal wasn't as large as adult females could grow to, and was probably happy eating fish and crabs in the Waitemata Harbour "and certainly not looking for anything bigger".
But dives are called off if the creature was in the immediate area.
"But I think if we put some measures in place to keep an eye out, we'd probably still go ahead with it, to be honest."
The seal has been named "Owha", meaning a relic, keepsake, gift, treasured bequest or inheritance.
Stay away from seals
• Stay at least 20 m away
• Don't disturb seals by making loud noises or throwing things
• Keep dogs and children away
• Don't feed them
• Never attempt to touch a seal.
Source: Department of Conservation