Eat more fish. But stick to kinds with less mercury.

That's the message federal regulators sent Tuesday in updating their advice on fish intake for pregnant women and nursing mothers, as well as women who might become pregnant and small children. The move does not require mandatory labeling of mercury content on seafood packages that some consumer groups have sought.

Previously, the Food and Drug Administration and the Environmental Protection Agency had recommended maximum amounts of fish that those groups should consume, but not a minimum amount. The new guidance advises pregnant women to eat at least 8 ounces and as much as 12 ounces per week of fish low in mercury, in order to promote fetal growth and development.

"For years many women have limited or avoided eating fish during pregnancy or feeding fish to their young children," Stephen Ostroff, the FDA's acting chief scientist, said in an announcement. "But emerging science now tells us that limiting or avoiding fish during pregnancy and early childhood can mean missing out on important nutrients that can have a positive impact on growth and development as well as on general health."

Halibut Fillet with Agrodolce Pesto (Photo by Renee Comet for The Washington Post) Halibut Fillet with Agrodolce Pesto (Photo by Renee Comet for The Washington Post)

Mercury has the potential to damage neurological development of infants and young children, and some studies have suggested that mercury almost might pose health risk in adults.

These are fish the government recommends staying away from due to high mercury levels: Shark, swordfish, king mackerel and tilefish from the Gulf of Mexico. Fish that are lower in mercury: Pollock, salmon, shrimp, talapia, catfish, cod and canned light tuna.

The agencies, however, did recommend limiting consumption of white, or albacore, tune to 6 ounces per week. In addition, the government said women and children should follow advisories from local officials when eating fish caught in local streams, rivers and lakes. Absent such information, pregnant women should limit their intake of such fish to 6 ounces a week, and no more than 3 ounces for children.

Tuesday's move has been under consideration - and debate - for years.

The FDA and the EPA both have a role in protecting the public from mercury contamination. The FDA regulates mercury in seafood that is sold in grocery stories and restaurants, while the EPA is responsible for overseeing mercury and other contaminants in fish caught for recreation.

In 2004, the two agencies issued their first joint advisory on the subject of fish consumption pregnant women, nursing mothers, infants and children, saying that those groups should stop eating specific kinds of fish high in mercury. At the time, government officials also suggesting limiting consumption of other mercury-contaminated fish.

In 2008, the FDA urged changes to the recommendations, saying that the benefits of seafood outweigh the health risks and that most people should eat more fish, even if it contains mercury. The prompted sharp criticism from some scientists at the EPA and environmental advocates, one of whom accused the FDA of becoming "nothing more than a patsy for polluters."

Tuesday's recommendations appeared to be an attempt to balance the varying views on how much mercury is safe for certain vulnerable groups. But it is unlikely to satisfy consumer advocates who have long pushed the FDA to require labeling on seafood packages disclosing mercury content, saying such an approach would be more effective than hard-to-remember government guidelines.