It came bottom in Greenpeace's 2011 tuna league table, but now Princes is looking to improve its sustainability credentials by becoming the first major brand to offer a 100% pole-and-line-caught range of tinned tuna.

The six-strong range of skipjack tuna steaks, to be launched to the trade in July, will be Princes-branded, but labels will bear a logo flagging up the pole-and-line method to differentiate them from Princes' other tuna products, which largely use tuna caught with purse seiners.

The new range was aimed at "shoppers who have a tendency to be more sustainability-minded and who are interested in ethical-type matters," said Ruth Simpson, marketing director at Princes.

She would not reveal the rsp but admitted that the range, which comprises three 80g tin twin-packs in olive oil, brine or spring water and three 160g tin variants in sunflower oil, spring water and brine, would be more expensive than Princes' standard tuna. There would also be less frequent promotional activity. However, the range would still have an "everyday low price".

Although Princes has used some pole-and-line-caught tuna in its standard cans for many years, the new range marks the first time the company has sold a specific, 100% pole-and-line range under the Princes brand. "It's a good ­advancement in terms of offering consumer choice. The step change is actually telling consumers it is a pole-and-line-sourced ­product," said Simpson.

She denied the range would cannibalise retailer own-label pole-and-line ranges because it would ­appeal specifically to brand-loyal shoppers.

In January, Princes came under fire for the fishing methods it used when it placed last in Greenpeace's 2011 tuna league table. It also drew flak from Hugh Fearnley-Whittingstall ­during his Fish Fight programme, on 13 January.

It subsequently announced in March it would purchase all its tuna from pole-and-line and FAD-free sources by the end of 2014.