Birds Eye is making a big play of the Omega-3 content of its new fish fingers to persuade consumers to switch from cod to pollock.

This month it launches Omega-3 branded fish fingers made from Alaskan pollock, which is in much more sustainable supply than cod.

However, instead of highlighting the fish variety, it has focused its £7.5m marketing budget on promoting the heart health benefits of Omega-3, in which pollock is higher than cod.

"We have learnt that sustainability issues don't change shopping behaviour," said Birds Eye customer marketing director Marc Kernick. "For years, we've been telling consumers that cod is king and, although nearly 85% of consumers are concerned about falling fish stocks (with about 90% aware that cod is most affected), 73% still buy cod regularly. Familiarity is more important than sustainability for most."

The move comes with the fish finger market in slight decline. With the concentration on cod, it has been hit by falling supply, rising prices and sustainability issues. Though producers have acknowledged the need to persuade consumers to switch from cod to other types of fish, previous attempts have failed.

Kernick stressed the importance of the new line's price tag, which is similar to its cod counterpart at £1.99 for 12 compared with £1.69 for 10 cod fingers.

"We've learnt not to compare any other fish to cod and not use price as a way of getting consumers to switch - they then think of the new fish as inferior to cod," said Kernick.

Birds Eye has altered the fish finger crumb recipe to take account of the fact that pollock is more moist than cod. The new line will also carry the Marine Stewardship Council's mark confirming that they come from a well-managed fishery and is the MSC's largest certified UK launch to date.

In the first 10 weeks after launch, nearly £3m of the budget will be used on a TV ad campaign and a partnership with a national newspaper. The launch will also get support from Birds Eye's ongoing Be Mortgage Free promotion.