What is the Sea Lamprey Diet?

The sea lamprey has a cylindrical body and smooth sleek skin. The vertebral column of a sea lamprey is made out of cartilage rather than bone, and as adults and pre-adults, they have a round suction cup mouth that is ringed with small teeth. Its diet reveals a lot more about how this aquatic animal lives.

Geography

Sea lampreys can be found on both sides of the northern Atlantic Ocean, in North America's Great Lakes and in the western part of the Mediterranean Sea. When they are larva, they hunt for food on the beds of muddy or sandy freshwater streams. As adults they hunt in the open sea or in lakes.

Features

When they are young and migrating toward open water, juvenile lampreys tend to eat landlocked salmon and different varieties of trout. As they get older and larger, they tend to prey on larger, apex predator fish like sprat , smelt, vendace and herring.

Method

Adult sea lampreys secure their food by latching onto it with their circular mouths. The suction holds the lamprey close to the side of the fish while its teeth tear into the victim's skin and muscles. This activity will kill smaller fish and wound and scar larger fish. According to New York States' Department of Environmental Conservation, there is a 40 to 60 percent mortality rate for fish struck by lampreys. Over its lifetime, an average lamprey will kill 40 lbs of fish.

Time Frame

Recently hatched lampreys will only prey on micro-organisms among decomposing plant material. This stage lasts between 4 and 6 years before they undergo metamorphosis. At that point, they are able to eat fish. Adult lampreys on their way to spawn will stop eating once they re-enter the river system.

Risks

Though the lamprey is considered helpful and edible in some countries, it is considered a threat to fish and the fishing industry in the Great Lakes. Sea lampreys decrease numbers of game fish and there are several measures used to control them. TFM (3-trifluoromethyl-4-nitrophenol) and granular bayluscide is used to kill off emerging lamprey larvae, while some sites erect barriers to prevent sea lampreys from returning to the rivers to spawn. Officials at the St. Mary's River in Canada catch male lampreys, sterilize them and then return them to the water.