A seal has died after a fight with a dog at Castlecliff Beach on Sunday, and Department of Conservation staff are urging beach visitors to be cautious and keep dogs on a leash.
Conservation partnerships manager Jasmine Hessell says the dog owner reported the incident to DoC. She had tried to separate the fighting animals and was bitten by the seal.
"The woman was in an area where she was permitted to exercise her dog, but it's timely to remind the public we share the coastline with a variety of wildlife, including protected species."
Seal pups often come ashore between July and October to rest after storms, and when they've been weaned they are learning to make their own way in the world.
"While they might look cute and harmless, seals are wild animals and will defend their territory aggressively. They carry infectious diseases and their teeth can inflict serious injuries," Ms Hessell warned.
"You should keep at least 20 metres away and not get between the seal and its escape route to the sea."
DoC staff are also investigating the death of a little blue penguin found at Castlecliff on Sunday and have found no obvious cause of death. The body has been sent to Massey University for an autopsy.
Penguins, which are protected, are known to come ashore in Wanganui. There are serious consequences for harming protected species. Those who deliberately injure or kill them face up to two years imprisonment or a fine of up to $250,000.
Senior DoC ranger Jim Campbell says motorbikes and dogs are the biggest threat to wildlife on local beaches. "We need to make sure our recreation activities don't harm any of our protected species."