Habitat – cold water seas, rivers, and lakes
Niche – parasite
Favorite Food – fish blood and tissues
Length – up to 4 feet
Weight – up to 6 pounds
Status – locally common
Forget the pale teenagers of the Twilight series. The true vampires of the world live in the depths of the oceans, rivers and lakes, fastening themselves to their victims with horrible teeth and sucking the life from them. For many fish, lampreys truly are creatures of nightmare.
The sea lamprey belongs to an ancient family of fishes that first appeared on Earth hundreds of millions of years ago. These primitive fish lack a true skeleton and are shaped like eels rather than most bony fish. Instead of jaws, they have a modified sucker on the bottom of their heads that is ringed with concentric circles of needle-sharp teeth. The sea lamprey uses this sucker to attach itself to fish that it locates with its keen sense of smell. Once attached, it’s nearly impossible to shake the parasite free, and the fish is doomed to suffer the lamprey’s toothed tongue raking out chunks of flesh and blood until it succumbs to loss of blood or infection.
Sea lamprey have similar life cycles as salmon, beginning their lives in rivers, then living their adult lives in salt water, and returning to the rivers to breed. After hatching from eggs, the young lamprey larvae burrow into the riverbed and remain there for many years, filtering tiny organisms out of the water for food. After they have attained a certain amount of growth, they will molt into their adult parasitic form. Because the larvae are intolerant to water above a certain temperature, lampreys are restricted to the colder waters north of the equator.
Sea lampreys are some of the most feared invasive species on Earth. If introduced to freshwater lakes and streams, they can decimate fish stocks, as was the case when they were first introduced to the American Great Lakes in the early 20th century. After the Welland Canal opened and linked Lake Ontario to Lake Erie, sea lampreys invaded the lower Great Lakes and wreaked havoc on the stocks of lake trout and other commercial fishes. Since that time, the lamprey population has been brought under control through a number of methods including selective poisons, physical barriers, and sterilization. However, like most invasive species, once the invader has spread, it’s nearly impossible to eliminate it entirely from an area.