The Silent Invaders

You may know about eels, but let me introduce you to a similar-looking creature called sea lampreys. While eels have jaws and bones like most fishes, sea lampreys do not have jaws and are made up of cartilage. Also known as the silent invaders, sea lampreys are parasitic fishes that latch onto their prey with their unique physical features. These jawless fishes have rows of teeth in a circle, called papillae, complete with a barbed tongue in the center. Lampreys use their mouths to suction onto their prey, and the victim is pierced with the lamprey's barbed tongue, allowing them to suck their prey's blood. 

Baby sea lamprey without eyes or mouth

Sea lampreys have a fascinating life cycle that is not similar to many fishes. When lampreys are born, they stay near the edges of rivers and streams. They are not born with eyes or mouths and are considered filter feeders since they are blind. Once they go through metamorphosis, they grow their eyes and mouths. Sea lampreys end up moving away from the area where they were born once they have matured, and they latch onto host fish for food. When lampreys mate, they move back to an area along the edge of rivers, where they then spawn. Not long after spawning, the sea lampreys die.

 

Impact of sea lamprey latching on a fish

While sea lampreys are protected in certain areas, such as Ireland, they are considered invasive in areas like the Great Lakes. With such a large fishing economy in this area surrounding the Great Lakes, sea lampreys take a toll on the number of fish available for commercial fishing. With an increase in sea lamprey, you see a large decrease in fish, resulting in a negative impact on jobs and sales for fisheries. 

There are some mitigation options that are being used on sea lamprey in the Great Lakes. Currently, the U.S. Fish and Wildlife Services are removing sea lamprey from the Great Lakes, not to be killed, but to be injected with pesticides that will prevent the sea lamprey from reproduction capabilities. This should help to reduce the number of sea lamprey that are spawned, and hopefully, keep the other fish in the Great Lakes at a stable number.