National is trying to "turn the West Coast into a political football" over whitebait, says Agriculture Minister Damien O'Connor.
National's Sarah Dowie has said whitebaiting could be at "risk of being banned if the Minister of Conservation gets her way".
The Conservation (Indigenous Freshwater Fish) Amendment Bill enables some areas of conservation land to be closed to whitebaiting.
On TVNZ1's Q+A, West-Coast Tasman MP Mr O'Connor said the bill does not ban whitebaiting, but instead places some protection for indigenous species under threat.
"It is about a legitimate move forward to offer some protection for indigenous species," he said.
"The idea that we could carry on without any change into the future and protect the fisheries is completely naïve... Most of the West Coast whitebaiters understand that something needs to change."
Mr O'Connor said the proposed law would offer flexibility to manage, "should the fishery get near to collapse, to close a river for a season".
"It is a cultural icon for many parts of New Zealand, not just the West Coast. But we do need to do something to better protect them, not just for us, but actually for future generations."
Q+A is on TVNZ1 on Mondays at 9.30pm, and the episode is then available on TVNZ OnDemand and as a podcast in all the usual places.