The head of the Federal Drug Administration told a U.S. Senate committee today her agency is still working on its review of an application to produce a genetically modified salmon.Download AudioDirector Margaret Hamburg gave no indication when the FDA would issue a decision.Actually we got … 33 or 35, 000 comments, so this is topic that people care a lot about. We’re going through those comments, taking them very seriously. And we will be moving forward in a science-driven way.AquaBounty Technologies says its fish would be farmed inland and would be incapable of breeding. Opponents, though, say the fish would threaten natural salmon runs and cause confusion in the marketplace. Ahead of the FDA decision, Friends of the Earth is pressing supermarket chains to agree not to carry the product. Last week, it added Safeway and Kroger to its yellow-light list of retailers, those that say they have no plans to carry genetically modified salmon. Target and Trader Joe’s made the environmental group’s green-light list with policy pledges not to carry the product.