State regulators have new data on mercury levels in fish caught in New Hampshire waters – and they want more anglers to donate fish for testing.

The state Department of Environmental Services keeps an interactive map of New Hampshire’s lakes, with data about invasive species, cyanobacteria, runoff and more.

Now, that map includes mercury concentrations in the tissue of fish in each lake – especially yellow perch and largemouth bass. Biologist Kirsten Nelson says wild freshwater fish like those build up mercury from other fish they eat.

“Basically the higher up the food chain you go, the more concentrated the mercury is likely to be,” she says.

The state already has guidelines on how much wild freshwater fish people should be eating in order to avoid mercury poisoning. It depends on species and where the fish were caught.

Officials say children and women who are or may become pregnant shouldn't eat any fish from certain water bodies or species due to mercury risks.

The toxic metal comes mainly from air pollution that blows into New Hampshire from Midwestern coal-fired power plants. But Nelson says those emissions – and coal use – are declining.

"And that will eventually show up in the fish we're eating,” she says.

The state would like to study that change more. But its data is patchy. It’s based mostly on fish that anglers donate – and those donations are at an all-time low.

Nelson says they'd welcome more – especially from places like Coos County, larger lakes like Winnipesaukee, and species with data to build on like bass and perch.