The discovery was made because researchers were looking for a way to extend the lamprey growth period – leaving them more vulnerable to pesticides.
At their peak the invasive species killed roughly 100 million pounds of Great Lakes fish a year – and researchers say they are always looking for new ways to fight the fish.
Marc Gaden is with the Great Lakes Fishery Commission.
“We are dedicated to finding every weakness in this beast and using it against them. These techniques that we come up with are all pieces of the puzzle and we are anxious to use this knowledge against the lamprey.”
The study found that in environments where food was readily available during their growth period roughly 56 percent of the lamprey were male. In harsher environments where the growth period was extended that number was as high as 78 percent.
Gaden said they are looking into how this new information can be used in the fight against the lamprey.