Objectives
After participating in this activity, students will be able to:
- Discuss the differences among the various types of technology used to control the lamprey population.
- Locate the lamprey-associated, spawning ground "hot spots" in the Great Lakes.
- Describe parasite/host relationships.
- Identify the placement of the Great Lakes and describe how the lakes are connected.
Summary
Sea lampreys have been one of the most devastating invader species to enter the Great Lakes. Over time, they’ve contributed to the decline of native fish populations and threaten a multi-billion dollar commercial fishing industry. By learning about sea lamprey, students begin to understand how harmful exotic species can become and how expensive and complex it is to control an invasive species once it’s established.
Background
Sea lampreys are eel-like fish that are native to the Atlantic Ocean. Since the 1830s, they have been migrating into the Great Lakes via Lake Ontario and the Erie Canal. Niagara Falls acted as a natural barrier for sea lampreys until the Welland Canal was improved in 1919. Once sea lampreys entered Lake Erie, they quickly spread to Lake Huron and Lake Michigan. In 1938, sea lampreys entered Lake Superior by attaching to ships passing through the Soo Locks on the St. Marys River. Because sea lampreys attach to and feed on native freshwater fish, they have posed a serious threat to whitefish, lake trout, and salmon during the past 50 years.
A single lamprey is capable of consuming 40 pounds of host fish in its lifetime. During an adult lamprey's 18-month life span, it will attach to a host fish with its suction-like toothed mouth, then suck nutrition out of the host fish, often killing it. The rapid decline in the number of native freshwater fish affects a Great Lakes sport and commercial fishing industry valued at almost $4.5 billion annually.
Biologists use a combination of methods to control the sea lamprey population in the Great Lakes. Several types of mechanical and electrical barriers have been constructed in strategic locations on Great Lakes tributaries. The barriers allow native freshwater fish to migrate upstream but block sea lampreys from reaching spawning habitat. Sterilization programs for male sea lampreys have also reduced the sea lamprey population. Finally, a special chemical that kills sea lamprey larvae, and an underwater high-power vacuum have both been used in the St. Marys River lamprey spawning grounds to eliminate thousands of lamprey larvae.
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