A DOC spokesperson said since then, another eight seals, including a pup, were found dead several hundred metres north of Half Moon Bay.
A Massey University pathologist determined the eight adult seals died from being shot.
The cause of death was not able to be determined from necropsies on another two adult seals and the seal pup.
"Necropsies weren't possible on other seals because of decomposition or not being able to access them," they said.
DoC South Marlborough operations manager Phil Bradfield said although the cause of death hasn't been able to be established for 11 of the seals, the fact the seals died grouped closely together gives cause for considering all the seal deaths suspicious.
"It's disturbing and deeply disappointing to know someone has deliberately shot and killed at least eight fur seals.
"Te Rūnanga o Kaikōura and DoC take very seriously any harm to fur seals which are a taonga and legally-protected species.
"We're hoping people will come forward with information to help us find whoever is responsible for the heartless shooting of at least eight of the seals."
The seals are believed to have died within the last month.
It's not been possible to closely examine the six dead seals in the Ōhau Point Fur Seal Sanctuary because it would disturb pregnant females and young pups in the breeding colony.
The penalties for harassing, disturbing, injuring or killing a marine mammal under the Marine Mammals Protection Act 1978 are a maximum two years' imprisonment or a fine up to $250,000
Anyone who has information about the deaths is asked to contact the DoC 24-hour number 0800 DOCHOT/0800 36 24 68 or Kaikōura Police via 105 and quote file number 211103/1981.
Alternatively, information can be provided anonymously through Crime Stoppers on 0800 555 111.
