What is it about mercury and fish that spawns (sorry) such fishy science? For the second time in a year, industry has tried to undercut the government’s advice that mothers-to-be should avoid mercury-contaminated fish. Their tactics: publicize industry-funded research that touts the benefits—and makes light of the risks—of eating fish. The latest such statement, issued last week by a group calling itself the Healthy Mothers/Healthy Babies Coalition (HMHB), touched off a new round of debate over eating fish and over the impacts of one-sided science on public understanding.

Last year, the hoopla followed a study by the Harvard Center for Risk Analysis, sponsored in part by the tuna industry (tuna is a big source of mercury in the diet because Americans eat so much of it and predator fish like tuna tend to have high levels of mercury). When researchers made a worst-case assumption—that people are too stupid to understand the government’s advice to eat less mercury-laden fish but keep consuming cleaner species—they got an unsurprising result: people would lose the heart-healthy benefits of eating fish. Duh. But in the scenario where people have half a brain and follow the government’s advice to eat fish but avoid certain mercury-tainted species such as swordfish, tilefish, shark, king mackerel, and albacore tuna, both their hearts and their babies benefited (mercury can be toxic to developing brains). And yet, the press release, and contrarian media stories it spawned, focused on the first scenario, concluding that “fish warnings do more harm than good.”

There is no evidence that Americans are so worried about mercury in fish that they’ve cut back on fish consumption. Quite the contrary: per capita fish consumption has grown steadily, and is at its highest levels since records began decades ago. But few Americans are aware of the government’s advice. Only about one-third say they have heard the warnings, and most of those who have can’t name the fish they should avoid.

Also clear is that the fishing industry is deeply worried that these warnings will sink their market. The U.S. Tuna Foundation, an industry group, launched a national campaign urging women to eat more tuna, and asserting that there is no scientific basis for concern about mercury’s effects on a baby’s brain. In asserting that mercury should not be a health concern, the tuna industry disagreed with the U.S. Food and Drug Administration, the Environmental Protection Agency, the National Academy of Sciences, the World Health Organization, and numerous other expert bodies. Yet the fishing industry sponsors a web site, fishscam.com, which claims that the concern about mercury is simply “hype” and that pregnant women should simply eat more fish.