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What is a Sea Lamprey?

Jacob Queen
Jacob Queen

A sea lamprey is a kind of parasitic fish that lives along the Atlantic coast. These animals look a little bit like eels, and they are generally brown in color with a lighter shade on their underside. They have a cartilage-based skeleton much like a shark, and an average adult will be about 2.5-feet-long (0.7 meters). They live on the blood of other fish by clinging to them like leeches. They can live in either fresh or salt water, and they are often seen as a pest in certain environments.

This fish has many rows of very sharp teeth, but it doesn't have a fully formed jaw. The mouth is generally designed for suction, which helps the sea lamprey stay latched onto the fish that they prey on. This suction is generally strong enough to keep the sea lamprey attached to both larger ocean species and smaller fish that are found in rivers and lakes.

Frog
Frog

Compared to many fish, the sea lamprey has a relatively unusual life cycle. For the first several years of its life, it is almost like a different animal. For one thing, they are much smaller, and they are totally blind. They generally stay this way for approximately four years. After that, their bodies change and they quickly develop their adult form. As a general rule, the young lampreys live in fresh water, and the adults live in the sea except when they are reproducing.

Many experts think that the sea lamprey takes a pretty hefty toll on fish populations in environments where they are prevalent. For smaller fish, they are probably often fatal, and even when a fish survives being attacked by a lamprey, it is likely that they may develop more slowly and end up being smaller because they are losing nutrients to the lamprey. This ability of the sea lamprey to attack fish populations has made them unpopular with commercial fishermen in their range.

Lampreys are especially unpopular among fishermen in freshwater environments because those areas have more fragile ecosystems. A large lamprey population can greatly thin out the number of fish in a lake environment or a river, and in many areas, there have been attempts to thin out the population of sea lampreys using various techniques and poisons. One method of lamprey control has been releasing sterilized male lampreys into the breeding environment, which can potentially lower the number of new lampreys born every year. Lampreys generally come into fresh water only for reproductive purposes, and the sterile males are released in advance of the breeding population's arrival on a seasonal basis.

Frequently Asked Questions

What is a sea lamprey and where can it be found?

A sea lamprey is an ancient, jawless fish with a funnel-like sucking mouth, native to the Atlantic Ocean and the Great Lakes of North America. It is an invasive species in the Great Lakes, where it has caused significant ecological disruption since its accidental introduction in the early 20th century.

How does the sea lamprey feed and what impact does it have on other fish?

The sea lamprey attaches to other fish with its tooth-filled mouth and rasping tongue, feeding on their blood and body fluids. This parasitic behavior can severely injure or kill host fish, posing a major threat to commercial fisheries. According to the Great Lakes Fishery Commission, sea lampreys can destroy up to 40 pounds of fish during their adult lifetime.

What methods are used to control sea lamprey populations?

Control methods include the application of lampricides, which are chemicals specifically designed to target lamprey larvae in rivers. Additionally, barriers and traps are used to prevent adult lampreys from reaching spawning grounds. The Great Lakes Fishery Commission reports that these methods have reduced sea lamprey populations by up to 90% in some areas.

Do sea lampreys have any natural predators?

Sea lampreys have few natural predators due to their parasitic nature and habitat. However, some species of fish, birds, and mammals may prey on juvenile lampreys. In their native habitats, the balance between lampreys and predators is more stable, but in invaded ecosystems like the Great Lakes, predators have little impact on controlling their numbers.

Can sea lampreys be used for any beneficial purposes?

While sea lampreys are generally viewed negatively due to their invasive status, they have been used in medical research. Their unique physiology, particularly their regenerative capabilities, offers insights into nerve repair and regeneration, with potential applications in treating human spinal cord injuries.

What is the life cycle of a sea lamprey?

Sea lampreys have a complex life cycle that begins with eggs hatching in freshwater streams. The larvae, known as ammocoetes, burrow into the sediment and filter feed for several years. They then undergo metamorphosis into parasitic adults, migrate to the sea or lakes to feed on other fish, and return to freshwater to spawn and die.

Discussion Comments

chrisinbama

@dill1971: That’s a really good question. I did a report on it in my Biology class and it’s really hard to understand. The way that the UMESC explains it is that the chemicals are poured into the lakes that are infested with the sea lampreys. It kills the sea lampreys when they are young. When the lampreys eat the chemicals or get covered in the chemicals, it will die before it matures. That means that the lamprey will not be able to harm any of the native fish or produce any more lampreys.

From what I’ve read, this method greatly reduces the lamprey population and somehow does not affect the other fish. Of course, some of the other fish die but the chemicals seem to attract the lampreys the most.

dill1971

@chrisinbama: How do those chemicals work? I mean, how can you have a chemical that affects one fish but not another?

chrisinbama

The sea lamprey is native to the Atlantic Ocean in which the Great Lakes are connected to. They are a huge problem in the Great Lakes because the native fish, such as the trout, are in danger of dying out due to the sea lamprey.

The Upper Midwest Environmental Sciences Center has been working on ways to reduce the number of sea lampreys in the Great Lakes. They have tried moving them out but that wasn’t very effective. They are working on chemicals that are designed to kill the sea lampreys without bringing harm to the native species. A couple of the chemicals they are working in are Bayluscide and TFM.

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