Two sub-adult male sea lions (pakake) were found dead and a third grievously injured on Saturday.
The third was euthanised following veterinary assessment.
All three had wounds consistent with being shot by a firearm.
"As a country we pride ourselves on our native wildlife and these acts are not who we are. Our precious taonga deserve much better," Department of Conservation southern South Island operations director Aaron Fleming said in a statement yesterday.
Waitaki District Mayor Gary Kircher said the "senseless slaughter" of the sea lions cast a bad light on the district.
"It’s breaking the law, it’s pretty damaging to our reputation in terms of looking after the wildlife and it’s something the Waitaki district doesn’t need."
Te Rūnanga o Moeraki chief executive Trevor McGlinchey was appalled by the news.
"Pakake are taoka [treasured] species to us and were highly valued by our tūpuna for their flesh, fat and pelt. We support the police and the Department of Conservation in seeking to find and lay charges against whomever shot these pakake."
New Zealand Sea Lion Trust co-chairman Shaun McConkey said the news was devastating, especially as it came less than a year after two sea lions were shot and killed in The Catlins.
"It is heartbreaking to think there are people out there who want to harm such curious, social and charismatic taonga.
"The trust has been encouraged to see attitudes improve in Dunedin where sea lions have become more common and accepted.
"It is therefore extremely disappointing to see that some backwards attitudes still exist in other areas where sea lions are just starting to establish."
He encouraged people to continue voicing their outrage at these types of incidents.
"Please speak up against these heartless acts.
"If you are having conversations with others let them know this behaviour is not acceptable.
"Such people are thankfully in the minority but they need to know this sort of behaviour won't be tolerated."
Mr Fleming said the incident was "completely horrifying and simply not good enough".
It is illegal to injure or kill protected native wildlife such as sea lions and anyone who does can face up to two years’ imprisonment and/or a fine of up to $250,000.
— If anyone has relevant information, they are asked to call police on 105 quoting event number P063434540, or to visit the Oamaru police station.
