"We have a good business provided we can keep bringing our costs down and operate within the volatile pricing of the international coal market.
"These proposed changes in management and support services jobs reflect that and are necessary to ensure the mine's profitability in the current market for steel-making raw materials, including the high-quality coking coal the mine produces for export," Ford said.
The aim was to "simplify" the mining operations at Stockton to reduce exploration, resource proving and other activities which went into new pit development, he said.
These changes were essential for Stockton to operate at current international steel coal prices of around US$131.50 tonne, versus US$225 a year ago and US$330 in mid-2011.
Earlier in the week, NZ Herald reported that hard-coking coal had plunged in price from US$290 ($367) a tonne to about US$140 since 2011.
Craigs Investment Partners said that with prices below US$140 a tonne "the consequences for the coking coal industry could be quite severe".
Craigs broker Peter McIntyre said: "If coal prices get much lower, I'd be surprised if many of the high production-cost operators can keep going."