Fisheries Act 1996, s 2 (“sale” definition), s 89(2)(a)
Amateur or recreational fishing means not fishing for the “purpose of sale” – but “sale” here also includes barter.
Some “fishing” falls outside these rules – for example, whitebait. On the other hand, some that you might not expect to be covered do fall within the rules – like eels and wai kōura (freshwater crayfish).