National says a pledge against shark finning, signed by other political parties, is a political stunt.
It is already illegal to fin live sharks but the pledge would require the entire animal to be brought ashore, rather than be dumped at sea.
Green MP Gareth Hughes says finning is being banned in many other countries because it is wasteful and damages shark populations.
But Primary Industry Minister David Carter, says there is already a process underway to increase the regulation of finning and the pledge is a political stunt.
