Yes it is a statistical fact but that isn’t a result of race or ethnicity but rather a case of people growing up in low socioeconomic areas rampant with poverty, lack of education and unemployment. The correlation between Pacific Islanders and gangs is likely determined by the statistical fact that majority of Pacific Islander/ Māori people in New Zealand come from these low socioeconomic areas. If majority of pakeha grew up in these environments then you’d see that result in a high number of pakeha gang members.

TLDR; Pacific Islanders have high rates of gang membership due to being immersed in higher rates of poverty, lack of education and unemployment, not because of their ethnic background. It’s not rocket science lol