The state Department of Natural Resources wants trout anglers to report gill lice.
The parasitic crustacean attaches to brook trout's gills, making it hard for the fish to breathe and slowing growth and development.
The creatures have always been present in streams and pose no threat to human health. But DNR officials don't have a good idea of how widespread the lice have become and they say more anglers have been encountering lice since 2010.
Agency officials are asking trout anglers to fill out a report for every outing documenting the general location, the trout species they caught and whether they observed any lice on the fish or not. The report form is available on the Trout Unlimited website.