The Department of Conservation are appealing for information after someone reported seeing owners "egging their dog on" to attack a female fur seal at a New Plymouth beach on Sunday.
DOC say the report stated the small seal was left injured and distressed, leaving a pool of blood in its wake before swimming into the water at Back Beach.
Department of Conservation Senior Ranger of Biodiversity Callum Lilley issued a warning for people to keep their dogs under control after the incident.
"It's disappointing that these people didn't have their dog under control and appeared to be actively encouraging it to attack the seal," he said.
In a statement today Mr Lilley asked anyone with information about the attack to contact the DOC New Plymouth office.
"We remind people that it's an offence under the Marine Mammals Protection Act to disturb, harass, harm, injure or kill a seal. A dog owner whose dog attacks a seal could face prosecution."
DOC reminded the public that anyone charged under the Marine Mammals Act with harassing, disturbing, injuring or killing a seal faces a maximum penalty of two years' imprisonment or a fine to a maximum of $250,000.