Child, Youth and Family chief social worker Paul Nixon said the agency handed fewer serious cases that required intervention to community or non-governmental organisations, but CYF continued to deal with serious or critical cases.
"That's exactly what's happening, and that was the strategy, to get more [external] agencies involved earlier in the lives of these children.
"Another agency can get involved and get close to that child and family and provide real services."
Bay family violence prevention organisation DOVE said there was "a lot of work going on" to reduce violence in the Bay, but said fragmented efforts to stem abuse in the past hadn't been as effective as hoped.
"If we keep doing what we're doing, we're probably not going to make a lot of difference. We need to be doing things differently," said manager Malcolm Byford.
"What we don't know is what that new system or entity would look like, but what we've got to do is try different things."
Mr Byford said he was optimistic the Government's recent announcement of "sweeping reforms" to combat rates of family violence and abuse would have a positive effect.
Justice Minister Amy Adams and Social Development Minister Anne Tolley announced the reforms to combat the "horrific" rates of family violence and abuse in New Zealand.
"Young people exposed to family violence ... are four times more likely to commit sexual violence against a partner ... three times more likely to attempt suicide, and 57 per cent leave school without a qualification," Ms Adams said.
Nationally, CYF found 16,394 cases of substantiated child abuse or neglect in the June 2016 year - 45 each day. About 8500 cases were emotional abuse, 3600 were neglect, 3100 were physical abuse and 1200 were sexual abuse.
The total figure has dropped each year since the 22,984 cases in 2013.
The Government said family violence figures were likely five times higher than reported.
Mr Nixon said it was difficult to definitively say abuse had fallen, despite lower numbers of substantiated abuse recorded by the agency.
"I don't think we know yet ... We have to watch the trends over time.
"Child, Youth and Family's focus is not on whether particular numbers go up or down; it is on whether we are making the right decisions when we get notifications."
Mr Nixon said the 17,000 fewer cases nationwide requiring CYF action over the past four years - a 28 per cent decrease - were picked up by other agencies.
Amanda Meynell, national manager of child abuse prevention charity Child Matters, said there were many dedicated efforts to reduce abuse, but it's difficult to draw strong conclusions from the data because of the unknown extent of unreported cases.
"While we're talking about the tip of the iceberg, actually that's 16,000 children who have suffered at the hands of people who are supposed to love and care for them," Ms Meynell said.
