Growth Rate Can Establish the Sex of Sea Lampreys

Sea lamprey

The growth rate of sea lampreys can establish their sex

Researchers from Michigan State University and U.S. Geological Survey discovered the sex of sea lampreys can be determined by the speed of their growth. Namely, slower growth rates during their larval phase might increase the changes of the lampreys to become males.

Growth rates influence sex determination in sea lampreys

The Great Lakes Fishery Commission reported that 78 percent of sea lampreys become male in environments with less food. However, environments with plenty of food, which allow for a better growth, produce only 56 percent males. This study might be important in developing technologies to control sea lamprey populations.

Initially, the researchers wanted to study only the effects of the environment on the growth rates of sea lampreys. Then, they ended up discovering how sex determination works for these creatures. Nick Johnson, the lead author of the study, explained why they think this is a big finding.

“We were startled when we discovered that these data may also reveal how sex is determined because mechanisms of sex determination in lamprey are considered a holy grail for researchers.”

Using the study to control sea lamprey populations

These creatures are an invasive species which live as parasites in the waters of the Great Lakes. They feed on the blood of the native fish species. This causes damage to the fishing businesses, as the populations of commercial and recreational fish species decline because of the parasite.

Scientists released larvae of sea lampreys in both productive and unproductive environments between 2005 and 2007. Then, they recaptured these creatures during their spawning migrations. They discovered that the unproductive environments were dominated by males. After changing into the adult stages, the sea lampreys did not switch sexes and they showed the same survival rate in both productive and unproductive lakes.

This study is important because the scientists can develop an advanced technique to control the population of sea lampreys and avoid further damage. Although they have already reduced the populations by 90 percent, they can still use new means to control them and influence their gender determination.

Thus, the researchers can now avoid further damage to their fisheries. They can develop a mechanism for a stricter control of the species, as they can disrupt or modify the gender of the specimens by making changes in their environment.
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