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L�ÝÝÊÄ 6

Why Should We Care about an Invader?

ACTIVITY 6.1 ͵ INVESTIGATING THE SEA LAMPREY BACKGROUNDACTIVITY 6.1 ͵ INVESTIGATING THE SEA LAMPREY BACKGROUND

What Will We Do?We will investigate the sea lamprey and the history of its invasion into the Great Lakes.

Procedure 1. Look over the information about the sea lamprey at the end of this activity sheet. It

includes an article, a picture of the sea lamprey, and a set of two maps.

2. Answer the questions using this packet.

Describing the Invader 1. Why do you think the sea lamprey is considered such a problem in the Great Lakes?

The sea lamprey is a problem, because it has eaten so many fish in the Great Lakes and has caused some types to become almost extinct.

2. Give two reasons why the sea lamprey has survived so successfully in the Great Lakes?

It has a large food supply and no natural enemies.

The Geography and Timing of the Invasion 1. Where does the sea lamprey live?

Their native territory is the Atlantic Ocean along the eastern coast of North America as well as the tributaries that feed the Atlantic Ocean. The invasive territory is the entire Great Lakes ecosystem of the United States and Canada including all of its tributaries.

 58പWHERE HAVE ALL THE CREATURES GONE?

2. Since the sea lamprey is a fish, can you explain why parts of the land near the Great Lakes and the Atlantic Ocean are also shaded on Map 1?

These portions of land are shaded to indicate the streams and rivers that directly feed into the Atlantic, and the Great Lakes where the sea lamprey go to spawn.

3. On Map 1, draw the path you think the lamprey took in order to reach the Great Lakes.

The path is from Lake Ontario via the Welland Canal— not the Niagara River— through to Lake Erie, and then to Lake Huron, Lake Michigan, and finally Lake Superior.

4. What geographic feature may have slowed the lamprey getting from Lake Ontario to Lake Erie? How do you think the lamprey was able to get around it?

Niagara Falls probably slowed down the lamprey from getting into Lake Ontario. When the Welland Canal was built, the sea lamprey was able to go through it to Lake Erie.

Discovering the New CompetitorFill in the following chart to show how the sea lamprey fits into its native environment compared to the invaded environment.

PredatorPredator PreyPreyNative Environment swordfish, sea bass, shark, and some

marine mammalstuna, swordfish, salmon, trout, shark

Invaded Environment none trout, whitefish, chub, and other bony fish

Student Data MaterialsThe sea lamprey is usually found in the salt water of the Atlantic Ocean. Like some fish (such as salmon), the sea lamprey travels to rivers or lakes to breed in fresh water. When it is young, it lives in the streams and feeds on tiny microscopic material that floats in the stream. As the sea lamprey gets bigger and enters its adult stage, it moves back to the Atlantic Ocean. In the ocean, it feeds on a variety of large fish, including tuna, swordfish, salmon, trout, and sometimes shark. While in the stream or in the ocean, the sea lamprey has to be careful not to be eaten by other fish such as swordfish, sea bass, shark, and an occasional marine mammal.

Lake Erie • Lake Huron • Lake Michigan • Lake Ontario • Lake Superior

Warren Downs, Fishery Commission

The Fishery Commission of the Great Lakes

 LESSON 6: ഩWHY SHOULD WE CARE ABOUT AN INVADER? പ59

Unlike some fish, the sea lamprey can live its entire life in either fresh water or salt water. It is this ability to live in fresh water that has caused so many problems in the Great Lakes. The sea lamprey affects both the fish and the fishermen. If the lamprey are killing the fish, the fishermen do not have as many fish to catch and sell. The freshwater Great Lakes are now connected by a large number of rivers and canals. Canals are man- made water passages to the Atlantic Ocean. These connections have allowed the sea lamprey to accidently enter the Great Lakes. Sea lamprey attach to big shipping boats that carry them to the Great Lakes.

The story of the sea lamprey invasion begins in Lake Ontario sometime in the early 1830’s. That is when local fishermen first discovered them. The next stop in the Great Lakes was almost a hundred years later in Lake Erie in 1921. The sea lamprey was soon discovered in Lake Huron in 1932, Lake Michigan in 1934, and finally Lake Superior in 1938.

The Great Lakes provided the sea lamprey with much food. There are about 125 different types of fish in the Great Lakes. Most of these fish are small and live near the coasts of the Great Lakes. The few, larger predators, such as the lake trout and burbot, live in the open waters of the Great Lakes. However, they do not feed on the sea lamprey. So, the sea lamprey has no natural predators in the Great Lakes. This means that the sea lamprey was free to prey upon the fish of the Great Lakes, especially trout, whitefish, and chub. The sea lamprey population increased quickly. Because they are not native to the Great Lakes, and they were increasing in population quickly, they were identified as an invasive species.

In 1955, the United States and Canada created an organization called the Great Lakes Sea Lamprey Committee. This committee studied how the sea lamprey survives so that they could create ways to remove it from the Great Lakes. This organization has spent much money to develop ways to remove the sea lamprey from the lakes. Some of the things they used have been successful, but even today the sea lamprey is present in the Great Lakes. With the support of the public and fishermen who make their living from the Great Lakes, this organization hopes to remove this fish from the Great Lakes forever.

The average length is 55 centimeters.

 60പWHERE HAVE ALL THE CREATURES GONE?

Note: *The Erie Canal was opened in 1819.**The fi rst Welland Canal was opened in 1829 and the second Welland Canal was opened in 1914.