In Northland, admissions for foreign objects had increased by one per year for the last two years, going from two in 2014 to four so far this year.
Canterbury admissions for foreign objects more than doubled from last year's, up to 12 from five, Fairfax reported.
Most did not need to stay in hospital for further care.
Further south the DHB bucked the trend, with fewer people admitted in Southern DHB's catchment area this year - down to just three from six last year and eight the year before.
In 2012 an eel was removed from a man's bottom in Auckland City Hospital, causing global headlines and 33 staff to be punished for looking at x-rays and information about the patient.
"The eel was about the size of a decent sprig of asparagus and the incident is the talk of the place," a hospital source told the Herald on Sunday at the time.
"Doctors and nurses have come across people with strange objects that have got stuck where they shouldn't be before, but an eel has to be a first."
The incident may also have been a last - no eels were reported in the latest statistics.