The Department of Conservation is asking dog owners to look out for wildlife and show responsibility when wildlife appears.

It said kiwis were also under attack as were little blue penguins and the situation was only getting worse.

In the southern South Island, from September 9, 2020, to August 12, 2025, there were 16 incidents of dogs attacking, killing or harassing sealions or seals, a statement from Doc said.

Doc principal investigation officer Hayden Loper said there had been seven deaths of sealions and seals in that time period.

"Deaths of seals and sealions have occurred in every year, with a noticeable spike in 2024," Mr Loper said.

"August is the most common month for attacks on seal and sealions, as it aligns with breeding season."

Last week, a man appeared for sentencing in the Nelson District Court on two charges relating to an incident in September last year when his two dogs attacked a fur seal on Kina Beach, near Motueka. He was fined $2000 and his dogs were ordered to be destroyed.

Doc also successfully prosecuted dog owners for seal attacks in 2020, 2017 and 2015.

Mr Loper said in the same five-year period, there were 96 incidents of other protected species falling victim to dogs.

There had been 27 incidents concerning kiwi in the period and 36 attacks on little blue penguins.

There was a clear upward trend in the number of incidents involving dogs and penguins -- climbing from six in 2021 to more than 20 already in 2025.

It was difficult to get enough evidence about an attack to prosecute, Mr Loper said.

"We often only have a dead or injured animal that has injuries consistent with a dog attack, but no evidence to link the injuries to an identifiable dog or owner.

"We might have a witness account or even photos of an attack but no way to identify the dog or owner.

"We haven't been able to establish causes or reasons for the trend, but the stats we compiled clearly show an increase -- hence our appeal to the public to help us.

"It's the owner's responsibility to keep their dog under control," Mr Loper said.

"It is not just untrained or aggressive dogs that kill protected wildlife -- even small, usually docile pets or well-trained hunting dogs can and do cause serious injury or death when not controlled."

Doc said although harassment was the most common type of incident, attacks and injuries had increased in recent years.

"Every person, business and community has a role in protecting and restoring nature -- particularly our vulnerable protected species."

Nineteen kiwi have been killed in the Bay of Islands already this year.