The charges included sexual violation, doing an indecent act and unlawful sexual connection with a girl aged 12 to 16, and abduction for the purposes of sexual connection.
Judge Collins noted that these were "strike offences" and gave the man a first strike warning, which will reduce his options for parole for any future offending.
The judge ordered a pre-sentence report but did not ask for electronic monitoring to be canvassed, again indicating that there was little prospect of a home detention sentence instead of imprisonment.
Defence counsel Laurie McMaster said the man had accepted there would be a "lengthy custodial sentence".
The judge remanded the man in custody until September 13 for sentencing.
A number of people were in the public gallery and one called out "The dogs are waiting" as the man was led away.
This was an apparent reference to gang members in prison.