A company announcement to the stock exchange said talks on his succession began last year and the board has already begun idenfifying likely candidates.
The move is part of a planned success process.
Candidate identification began in Novembeer and the board is now shortlisting candidates, it said.
Chairman John Wilson said the board decided to bring forward the announcement it expected to make in April to avoid speculation.
“It is not yet clear exactly when any appointment for Theo’s replacement will be made but it is absolutely clear that Theo will continue in the meantime to drive the co-operative’s strategy and business, with special emphasis on China.
“The board and Theo are committed to a high-quality transition to a new chief executive and when we have more information in regards to timing we will let our farmers and the wider market know.
“Until then it is business as usual with the focus on driving returns to our farmers and unitholders.
“We envisage that even after the announcement of our new chief executive, Theo will be involved in an advisory role so that we make best use of his knowledge and expertise during the transition,” Wilson said.
Spierings said he has been proud to have led Fonterra for seven years as the co-operative has established a strong demand-led strategy and oriented itself to become innovative and sustainable.
“It is now time for a new chief executive who can lead the co-operative through this next phase.
“The time is right for the co-operative and that is important to me and to the board.
“It is also the right time for me personally.
“I look forward to new challenges but right now my focus is on Fonterra. That will be the case until I finish with the co-operative.”
