Mr O'Connor, who has been with South Port almost 25 years in total, said he had advised the board about four years ago that once he turned 55, he planned to ''take a detour in the road and exit the port sector'', and after some overseas travel would return to New Zealand to seek out directorship positions.
South Port chairman Rex Chapman said the board was disappointed to lose a person of Mr O'Connor's calibre, given South Port's significant progress during the past two decades while he was chief executive.
South Port's annual dividend had increased from 5.5c per share to 26c while the share price rose from 86c to its current level of $5.35 - a $120 million gain in market capitalisation.
South Port's past financial year booked record cargo and profit, with volumes having lifted by 50%, or by about 1million tonnes, since 2009.
