Whanganui and Partners has lost "valuable insight and experience" with the resignation of board director and chairman Myles Fothergill.
Fothergill will step down from his role with the economic development agency and focus on his own business and family commitments instead.
"As the Whanganui Port Revitalisation Project gains momentum, I want to be able to focus on my future aspirations for my company, Q-West Boat Builders, and in that capacity to pursue economic growth opportunities for the port and indeed the wider business community."
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Fothergill said he's proud to be leaving Whanganui and Partners in good hands.
"It has been an absolute privilege to have played a part in creating an outstanding organisation that I have immense pride in.
"My thanks go to mayor-elect Hamish [McDouall] and elected members, as well as to council chief executive Kym Fell, for their immense support of Whanganui & Partners and myself over the past three years.
"The future of Whanganui looks bright."
Fell said Fothergill had significantly contributed towards the success and growth of Whanganui over the past three years.
"His valuable insights and experience will be missed; however, I am certain that the board will maintain the high level of leadership and support that Myles has helped establish.
"I completely understand the reasons for Myles' decision and I look forward to working with him as a key stakeholder in Whanganui's future port redevelopment and economic growth in the marine sector in Whanganui."
Fothergill will remain involved with Whanganui District Employment Training Trust, INTRANZ, 100% SWEET and Whanganui High School Board of Trustees.