A banner hung from a Dunedin bridge yesterday morning was part of a national Greenpeace effort to change Sealord's tuna-fishing practices.
Greenpeace launched a large outdoor campaign in Auckland with hundreds of posters, and a plane towing a banner, featuring Sealord's new logo and the words: "Nice Logo. Bad* Tuna. *Sealord's canned tuna is caught unsustainably".
Posters were also hung in Wellington and Dunedin, along with the banner on Roslyn bridge.
Greenpeace oceans campaigner Karli Thomas said "We've done quite a blitz".
"We're letting consumers know that Sealord is buying its tuna from fishing companies that are needlessly destroying marine life.
"There might be a new logo on the outside of the can, but it's still the same old tuna outside. Our message to Sealord is change your tuna, not just your logo," she said.
The initiative was part of Greenpeace's global campaign urging tuna brands to stop selling tuna caught using fish aggregation devices (Fads) with purse seine nets.
Its New Zealand campaign, targeting Sealord and Foodstuffs, was launched in April, with Foodstuffs announcing in June it would change most of its Pams range to Fad-free by the end of the year. However, Sealord was refusing to change its policy, despite receiving more than 13,000 emails from consumers, Ms Thomas said.
"Sealord is dragging the chain, so we ramped up the pressure on them."
Other tuna brands, including John West, have committed to phase out Fad-caught tuna and sell more sustainably-caught fish.
By-catch, including sharks, turtles and juvenile tuna, was about 5% when Fads - rafts with buoys attached which attracted tuna and other species - were used. It was about 1% when just nets were used, the International Seafood Sustainability Foundation said.
However, Sealord New Zealand marketing general manager David Welsh said the company's tuna was sustainable.
"By-catch is very low - 0.16% of catch is sharks and non-tuna species make up 1-2%," he said.
"All food production has impacts, and the fishing industry is lower than most land-based farming. We are investigating our legal options on how best to respond to this misleading attack," Mr Welsh said.
The banner on Roslyn bridge was removed mid-morning.