The Three Kings water reservoir tower has been turned into a giant Sealord tuna can and labelled bad tuna by Greenpeace activists.
The campaign urges tuna brands to stop selling tuna caught with large purse seine nets set around fish aggregation devices (FAD), a method used by many industrial fishing vessels, and to start using a more sustainable method.
Sealord today called the campaign "another example of misleading, extreme activism''.
"Sealord tuna is sustainable. Bycatch is very low: 0.16 per cent of catch is sharks, and non-tuna species make up 1 to 2 per cent,'' said Sealord marketing general manager David Welsh said in a statement.
"We are investigating our legal options on how best to respond to this misleading attack,'' he said.
The global Dolphin Safe environmental group had condemned the campaign as "misleading in the extreme'', Welsh said.
The advertising roll-out follows on from Greenpeace's campaign calling on New Zealand's main brands of canned tuna to stop selling fish caught using FADs, launched in April.
"According to information circulated by Sealord, bycatch of non tuna species is five to 10 times higher when purse seiners use FADs. This wasteful method also has a serious impact on tuna stocks, as juvenile and undersized tunas make up 15-20 per cent of the catch,'' said Thomas.
Foodstuffs announced in June it would change most of its Pams range of canned tuna to FAD-free by the end of the year.
- APNZ