Preying on Great Lake natives

Sea lamprey have been a large problem in the great lakes since the 1830’s when they are first thought to have infiltrated the great lakes. And by 1940 the sea lamprey had made it north to all of the great lakes. Sea lamprey are native to the Atlantic Ocean and entered the Great Lakes through man-made canals. Sea lamprey are very aggressive and lay a ton of eggs. Also they have no natural predators around here, which make it very easy for them to overwhelm an ecosystem like the Great Lakes. Sea lamprey parasitically feed on host fish by latching on to their side and using their teeth and tongue to suck out the bodily fluids of the host fish. Only one in every seven fish attacked by sea lamprey survives. During the parasitic life of the sea lamprey, each one kills anywhere between 15-40 pounds of fish.

The lamprey feed on larger fish, such as lake trout, salmon, steelhead, and whitefish, all Great Lake natives. During the 1940s and 50s sea lamprey were blamed the rapid decline in the number of lake trout. The US and Canada used to harvest 15 million pounds of lake trout but by the early 1960s, only 20 years after the introduction of the sea lamprey, only 300,000 pounds were harvested. This had a huge impact on the ecosystem because other species were able to reproduce rapidly with out the large fish preying on them. This also had an impact on the economy because fisheries struggled, fishing tourism went way down and also with all the dead fish washing up on the beaches its also took away from the beach tourism as well.

The sea lamprey have been a huge problem to the Great Lakes and the surrounding areas and we realized that a mitigation strategy was needed fast. In 1955 the Great Lakes Fishery Commission (GLFC) was created for the purpose of restoring fisheries and one of its main goals is to reduce the affects of lamprey. Lamprey traps and barriers were created but were not able to be efficient 100% of the time. So they produced the chemical TFM, which kill a majority of the lamprey and their weakest state, when they are buried under ground as larva. This was extremely successful and brought the lamprey population to 10% it’s original size allowing the lake trout to support themselves again. However research continues to try and find a safer and more effective way to remove the lamprey from the Great Lakes and universities such as Minnesota and our own Michigan State.

Sea Lamprey have been a nuisance for the Great Lakes but now with newer technology and better research the lamprey are one of the most successfully controlled invasive species. It is very important to keep the Great Lakes healthy because without them the consequences will be enormous.


  • Adam Kogelshcatz

2 responses

  1. Wow! i did not know these existed! They all about the size of the ones in the photograph? Why don’t they prey on humans?

    ~Gretchen Rambadt

  2. Great post! I was wondering about if anyone was trying to curb their effects when we watched that movie in class the other day that showed the lamprey. I’m glad to know that there are a few things going on to try to get rid of these things. They are scary looking too when they suck onto a fish like that! Yuck!

    -Jordan Burroughs

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