Lampreys, shown here, have been discovered in the Paw Paw River, a tributary of the St. Joseph River. (Photo submitted)

By AARON MUELLER
aaron@offthewater.com

A United States Fish and Wildlife Service assessment crew will be in the area this week to do a survey to detect the presence of sea lampreys in the St. Joseph River in Berrien County.

The eel-like, parasitic creatures have been a problem in the Great Lakes for decades and they have been discovered in the Paw Paw River, a tributary of the St. Joseph.

Sea lampreys can grow to be about 18 inches long and prey on a variety of fish.

“They actually drill a hole through the scales and feed on the blood and body fluids of the fish,” said Jeff Slade, the Ludington Biological Station supervisor for the U.S. Fish and Wildlife Service.

Slade said the lampreys begin as larvae hatched from eggs and after about four years metamorphose into parasitic adults that migrate to the Great Lakes and kill fish.

“Their favorite hosts are lake trout, lake whitefish and salmon,” Slade said.

Sea lampreys first invaded the Great Lakes in the 1920s and have been a permanent, destructive element of the fishery since. The average sea lamprey will destroy up to 40 pounds of fish, according to Slade.

An assessment crew will be working at six different plots of the river downstream from the Berrien Springs dam between July 7 and 15.

The information gathered from the study will determine the need for sea lamprey control in the river. Slade said the Fish and Wildlife Service tries to survey the St. Joseph River every four to five years as a preventative measure.