The number of family violence investigations carried out by police has hit a record high - putting pressure on already strained resources.
New statistics from Auckland University-based research centre Family Violence Clearinghouse show police investigated almost 119,000 incidents in 2016 - up more than 8000 on the year before.
In 2014, the figure was just under 102,000.
Researcher Pauline Gulliver said they could not pinpoint the reason for the rise.
"The general assumption is that more people are coming forward to report, but we actually really don't have any evidence to suggest that that would necessarily be the case, or that wouldn't be the case."
Either way, it was putting more pressure on already stretched resources and services, and Dr Gulliver said it was not just the police who were feeling the strain.
"We're talking about a social problem that has quite a large number of tentacles. There are a lot of other issues that go alongside and it's not just some sections of our population who experience it, family violence happens across the board, so we can't really be just pointing the finger and say it's their problem."
Women's Refuge chief executive Ang Jury said the increase in family violence investigations was worrying.
She said refuges across the country were helping more and more people each year, but their increase in workload was smaller than that faced by police.
"Our crisis line numbers remain high, our bed nights remain high, our client numbers in general remain high."
Dr Jury said they were not sure whether the increase was because people were more aware of their services, or whether there was more violence.
Concerns raised over police data
But the Family Violence Clearinghouse has also raised concerns that police data was compromised, because officers were not recording the victim's relationship to the offenders in the majority of physical and sexual assaults against women.
Research showed the vast majority of assaults on women were carried out by partners, ex-partners, family members and others known to them.
Dr Jury said failing to record that information was not good enough.
"That's really, really unhelpful. If we want to look at trying to change those numbers, we actually need to know the reality of those numbers. We need all of the information we can get."
Despite moves by the government to tackle family violence, Ms Gulliver said there was more that could be done.
She pointed to an almost $2 billion 10-year plan unveiled in the Australian state of Victoria to end family violence.
"The difference in scale of approaches is quite substantial, and ours tends to be a bit more piecemeal as well, so I think in terms of 'do we have adequate resources to deal with it?' I'm not entirely sure we do at the moment."
Dr Gulliver said a much broader approach was needed.
"Where you have communities that don't have adequate housing, that don't have adequate job opportunities and all those other sorts of issues that go alongside that, then we need to be addressing that, knowing that if we start addressing those sorts of issues, we're probably going to start addressing family violence in the long term as well."
In a statement, police said reducing harm from family violence was a high priority and they encouraged people to report any incidents to them.