Greenpeace’s largest ship, the ice class Esperanza, sailed up the Thames to Tower Bridge as part of its campaign against tuna brand John West.

The Esperanza had returned from the Indian Ocean where it was examining the fishing practices of John West owner Thai Union, which, the environmental charity says, harms marine life including sharks and turtles.

Tesco and Waitrose recently pledged to remove John West from their shelves but Sainsbury’s has refused to relent, despite a Greenpeace campaign , bringing the Esperanza to London to make its protest directly.

Sainsbury's says it is monitoring John West's work with wildlife charity WWF to improve its sustainability status and will re-consider its relationship should targets not be met.

In 2011, John West promised consumers it would go 100% sustainable, but Greenpeace discovered last year that just 2% of their tuna was caught using sustainable methods.

The Esperanza at Canary Wharf

The campaigners said that, in April and May, the crew of Esperanza tracked and removed “ fish aggregating devices ”, or FADs, from tuna fishing grounds directly linked to suppliers of John West. A FAD is a float tethered to the ocean floor to attract fish such as marlin, tuna and mahi-mahi. They kill 100,000 sharks a year.

Greenpeace revealed footage that appeared to show threatened species, including silky sharks, swimming under harmful fishing gear deployed by vessels supplying John West.

Oceans campaigner at Greenpeace Ariana Densham said: “The crew aboard the Esperanza have seen first-hand the harmful fishing gear used to catch John West’s tuna in the Indian Ocean and they’ve come to London to join the 100,000 people who have already told Sainsbury’s it’s totally unacceptable for them to continue to profit from it.

The Esperanza passes through the Thames Barrier

“Other retailers like Tesco and Waitrose have already committed to remove John West’s tuna and Tesco has even started taking their tins off shelves. Sainsbury’s prides itself on its reputation as a sustainable business, but for as long as it continues to profit from John West’s unsustainable seafood, it’s killing our oceans.”

Waitrose has set a deadline of the end of 2017 for John West and other branded tuna to meet the store’s sustainability criteria or be taken from the shelves.

Jeremy Ryland Langley, Waitrose’s aquaculture and fisheries manager, said: “When they buy a can of own-label tuna, our customers know that they are always buying a product which has been sustainably sourced – and now they will have the same assurance when it comes to buying a branded product.”

What Sainsbury's says

Sainsbury’s Sustainability Plan promises "we'll source our raw materials sustainably to an independent standard" and "our fish will be independently certified as sustainable".

A Sainsbury’s spokesperson said, "We are the UK’s leading retailer of sustainable fish. We wholeheartedly share Greenpeace's goal of improving fishing practices across the world, which makes it all the more disappointing to be the sole focus of this campaign.

"John West is working with WWF to drive up its sustainability status by 2018 and we are closely monitoring the progress. We have been absolutely clear that if targets are not met, we will reconsider our relationship with JW.

"But we know it's more effective to work with businesses to tackle issues rather than simply turning our backs."