WASHINGTON >> Pregnant women are being advised by the government to eat more fish, but there won’t be any labels or signs to let them know which fish have low mercury levels and are safest for dinner.

Without a labeling requirement, the draft advice issued Tuesday by the Food and Drug Administration and the Environmental Protection Agency is unlikely to clear up confusion among shoppers about what seafood pregnant women, young children and other vulnerable groups should avoid. Rather they’ll have to rely on memory — should they avoid swordfish? Yes. What about salmon? That’s OK.

Consumer groups have sued the agency, saying the warnings over the last decade haven’t been clear enough about what fish could pose a risk, and it’s hard for people to remember what’s good and what isn’t. Those groups asked for labels on packages or at fish counters.

For most people, accumulating mercury from eating seafood isn’t a health risk. But for a decade, the FDA has warned that pregnant or breastfeeding women, those who may become pregnant, and young children avoid certain types of high-mercury fish because of concern that too much could harm a developing brain. Fish can absorb small amounts of mercury, a neurotoxin, from streams and oceans — and some varieties of seafood harbor higher levels.

Echoing their earlier advice, the agencies said this population should not eat shark, swordfish, king mackerel and tilefish from the Gulf of Mexico because of the mercury content and advised limiting white albacore tuna to six ounces a week.

The FDA says the update is an attempt to get pregnant women to eat more fish, since many types of low-mercury seafood are good sources of omega-3 fatty acids important for brain development. The benefits of seafood are greater than the risks, said Stephen Ostroff, the FDA’s acting chief scientist.

The advice echoes the 2010 Dietary Guidelines, which say that pregnant women should consume at least 8 ounces and up to 12 ounces — or two to three servings — of a variety of seafood per week.

“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,” Ostroff said.

The advisory says many of the most commonly-eaten fish are lower in mercury, including salmon, shrimp, pollock, tilapia, catfish, cod, flatfish, haddock and canned light tuna.

The FDA said it did an analysis of more than 1,000 pregnant women in the United States and found that 21 percent of them ate no fish in the previous month, and most of those who did eat fish ate far less than the recommended amount.

The seafood industry has said the government shouldn’t look at mercury by itself, but at the overall benefits of seafood.

Jennifer McGuire of the National Fisheries Institute says the advice shows that the FDA has “begun the process of setting the record straight that fish should be a pregnancy staple.”

FDA and EPA said they will take public comments, seek the advice of the FDA’s Risk Communication Advisory Committee and conduct a series of focus groups before making the advice final.

Included in the draft is a table giving consumers more information on the levels of omega-3 fatty acids and mercury in certain fish, allowing shoppers to assess for themselves which fish are best. But the table does not include a recommendation for how much mercury is too much.

According to the table, orange roughy and marlin have levels of mercury that are significantly higher than other fish, but are not on the do-not-eat list for pregnant women and kids. The agencies say they are taking comment on whether those two should be included in the warning list.

Sarah Klein of the Center for Science in the Public Interest, one of the groups that filed suit against the FDA, says the extra information is helpful but could still be confusing.

“What remains to be seen is how FDA plans to inform consumers of that advice,” Klein said. “How can consumers be expected to retain this information when they are in the middle of grocery shopping?”