No incidences of sex trafficking were found in New Zealand after decriminalization of sex workers.
Please read Page 167 at the study linked below:
http://prostitutescollective.net/wp-content/uploads/2016/10/report-of-the-nz-prostitution-law-committee-2008.pdf
Here is an excerpt from that page:
“Information received from Immigration Service NZ indicates that no situations involving trafficking in the sex industry have been identified (Department of Labour, 2007). In addition, there have been no prosecutions for trafficking under section 98D of the Crimes Act 1961.85.... The Committee is satisfied, on the basis of information received from NZPC and other NGOs involved with street-based sex workers, that during its period of investigation, there were no internationally trafficked women working as street-based sex workers in New Zealand.”
http://prostitutescollective.net/wp-content/uploads/2016/10/report-of-the-nz-prostitution-law-committee-2008.pdf
Here is an excerpt from that page:
“Information received from Immigration Service NZ indicates that no situations involving trafficking in the sex industry have been identified (Department of Labour, 2007). In addition, there have been no prosecutions for trafficking under section 98D of the Crimes Act 1961.85.... The Committee is satisfied, on the basis of information received from NZPC and other NGOs involved with street-based sex workers, that during its period of investigation, there were no internationally trafficked women working as street-based sex workers in New Zealand.”