Animal welfare activists are calling for humane treatment of animals to be taught in schools, after news that four teenagers killed a seal near Dargaville two weeks ago.

The female leopard seal was found dead after being shot in the head at Glinks Gully Beach on July 28.

Police have now identified four teenage boys who were involved, two aged 16 and two aged 15, who will all be referred to Youth Aid.

Hans Kriek of Save Animals From Exploitation (SAFE) said it was "completely unacceptable to have teenagers in society who think shooting seals is fun".

"When we have 15- and 16-year-olds involved in senseless violence to animals, we need to ask ourselves what we as a society have done to contribute to this behaviour," he said.

"Teaching values and attitudes of compassion and respect to animals needs to be part of our curriculum. It's time New Zealand made humane education compulsory in schools."

SAFE's education programme, Animals & Us, has been promoting and fostering compassionate and respectful attitudes towards animals for over a decade. The programme's textbooks are aimed for use within the NCEA curriculum and cover topics including animal rights, factory farming, and animal experimentation.