WASHINGTON (AP) — Don't expect to find genetically modified salmon on store shelves anytime soon. The Obama administration has stalled for more than four years on deciding whether to approve a fast-growing salmon that would be the first genetically modified animal approved for human consumption. During that time, opponents of the technology have taken advantage of increasing consumer concern about genetically modified foods and urged several major retailers not to sell it. Safeway and Kroger have already pledged to keep the modified salmon off their shelves. Proponents of genetically engineered fish or meat say they still hope to find a market and expect the Food and Drug Administration to approve sale of the salmon. But caution by retailers and lengthy regulatory delays have made investors skittish.