Seven open investigations into marine mammals at the Department of Conservation range from the sad to the bizarre, including a complaint over a person throwing doughnuts at a seal.

Late last month, a two-year-old female sea lion was found injured by a member of the public at Aramoana Beach with a later necropsy – an examination of an animal after death – confirming the animal had been shot.

That death prompted a plea from DOC for any information, with the person behind that shooting yet to be caught.

The death of the protected sea lion was one of seven open investigations under the Marine Mammal Protection Act.

Under that Act, anyone found disturbing, harassing, harming, injuring or killing a New marine mammal, could face imprisonment for a term not exceeding two years, or a fine not exceeding $250,000, or both.'

Those seven open investigations were "spread right across the country", says Coastal Otago operations manager Gabe Davies.

But three of those were in coastal Otago, including the killing of the young sea lion.

DOC later released a brief summary of those seven investigations where human behaviour is considered a factor.

These investigations include a weapon being pointed at a seal, a person posting online about a removed jaw from a dead beached whale and a complaint about a person “throwing donuts” at a seal.

DOC is not in a position to discuss any of these investigations, including where and when those incidents occurred, or even the complaint over why a person was throwing doughnuts at a seal.

Last year, Sky News reported a local seal, dubbed Spearmint, had become too reliant on food, including doughnuts and sandwiches, handed to her by English beachgoers in Devon and Cornwall.

That led to the young seal seeking only food given to her by humans.

She was later released back into the wild, after being in the care of Britain’s SPCA.

The killing of the sea lion at Aramoana is one of numerous cases across the country, and asked how difficult it is to bring a prosecution under the Act, Gabe says any case is based on the evidence available and what investigations reveal.

A complaint of someone throwing doughnuts at a seal prompted an investigation by the Department of Conservation. Photo: Robert Kitchin/Stuff.

"We work within the available legislation and what that allows us to do - both in terms of compliance options and penalties we can pursue."

One high profile prosecution involved two men who killed 23 New Zealand fur seals on the Kaikōura coast in late 2010.

The fur seals, including some newborn pups, were beaten to death with a galvanised steel pipe at the Ohau Point seal colony.

In 2005, three men, including Andrew Hore, were each fined $2500 for shooting at seals, killing one, on the Otago coast, with the All Black receiving diversion.

While a case against a Dunedin man originally charged over stabbing an 11-month female sea lion Rua in Otago Harbour in 2016, later collapsed.

Anyone with information about open cases is urged to contact 0800 DOCHOT.

-Hamish McNeilly/Stuff.