Port of Tauranga chief financial officer Steve Gray will step down next year for health reasons.
Considered by the sharemarket to be a significant contributor to the port company's success, Gray has been in the job 12 years and with the company 32 years.
He will retire in June.
The search for his successor would start immediately, said chief executive Mark Cairns.
Gray had overseen outstanding returns for shareholders, leading negotiations for the company's long-term freight agreement with Kotahi that enabled the port to become big ship capable and New Zealand's largest port, Cairns said.
Gray was named CFO of the Year at the 2017 Deloitte Top 200 Business Awards.
He would continue in governance roles in the port company's associate companies, including PrimePort Timaru and Coda Group, said Cairns, who also announced other senior management changes.
To prepare for Gray's retirement, finance and IT manager Simon Kebbell would become company secretary. Kebbell joined the company in 2003 and was previously with Ernst & Young and PwC in Singapore.
The port's commercial manager since 2013, Leonard Sampson, had been appointed to the new job of chief operating officer.
Sampson has held senior roles at KiwiRail, Carter Holt Harvey and Mainfreight.
The company's share price today fell 15c to $6.30.