These Horrifying Fish Need Your Help To Thrive In MA Waterways: State

MASSACHUSETTS — Avert your eyes, because one of the worst looking fish on planet Earth needs your sympathy.

The sea lamprey — a 340-million-year-old species whose main feature is a disk of spiked teeth used to harvest blood — is a type of parasitic fish that spawns in fresh water but otherwise lives in the ocean, similar to salmon.

The mini shai-hulud of Massachusetts use the Merrimack and Connecticut rivers and other connected waterways around this time of year to spawn, according to the state Division of Fisheries and Wildlife. Dams, pollution and other man-made obstructions have made spawning difficult for lampreys, who previously survived four other mass extinctions on Earth.

This spring, the state is asking people who use the rivers to leave sea lampreys alone so they can continue to breed, as unpleasant as that may sound.

"Anglers and others recreating on the river can protect sea lamprey populations by simply letting them be as they go about their spawning behavior. You can also let others know that lampreys found in rivers are not a threat to native fish or to people," DFW said in a recent appeal on behalf of the terrible looking lampreys.

Sea lampreys are parasites, but they do not pose any threat to humans. But if you're a bony fish like a cod or trout, lampreys are bad news.

"The oral disk allows them to attach, and the toothed tongue allows them to rasp a hole into the side of a host fish and feed on its blood," the U.S. Fish and Wildlife Service described.

And while conservation officials in Massachusetts are trying to preserve the local sea lamprey population, the species has caused havoc across the Great Lakes. For centuries, sea lampreys couldn't enter the lake ecosystem due to Niagra Falls. The opening of the Welland Canal through eastern Ontario allowed the lampreys to spread from Lake Ontario into Lake Eerie and to the remaining lakes beyond.

Lampreys devastated the Great Lakes fish population. The Great Lakes Fishery Commission has used an array of tactics, from "lampricide" poisons that target larvae to physical barriers to reduce the lamprey population to a fraction of its peak in the 1940s.

Back on the Atlantic coast, New England states are trying to conserve the species. Sea lamprey larvae are an important food source for birds and some fish, and their decomposition provides nutrients for local waterways. States like Connecticut and Vermont have asked residents to leave lampreys alone, as horrible is they look, because they do not pose a threat to freshwater fish in New England.

"There is no reason to harm these fish," the Connecticut Department of Energy and Environmental Protection wrote in a social media post last month after responding to reports of lamprey killings.