Russians are consuming less of the prized delicacy compared with a couple years ago, but only because the price of the tiny black sturgeon roe has increased, it said.
Rising prices discouraged 68 percent of respondents from buying caviar, the WWF survey said, while only 4 percent cited the collapse of Caspian Sea sturgeon stocks as a factor in the decline.
"We found that our countrymen don't think of the environment when they eat caviar, but the rising prices are making people buy less and less," WWF's Moscow spokeswoman Darya Kudryavtseva said.
"People are ready to buy illegal caviar. The fate of sturgeon and the legality of caviar is of little concern to Russians," she said.
Last month Russian police seized almost half a tonne of contraband caviar worth an estimated $600,000 as it was being smuggled through a military airfield in black rubbish bags, the interior ministry said at the time.
Overfishing, poaching, pollution, poor management and corrupt law enforcement agencies have cut sturgeon stocks severely, environmental groups have said.
Caviar from the rare beluga sturgeon costs about $1,800 per kg in Moscow markets, versus 3,700 British pounds ($7,499) in London, though other types cost less.