Human activities that add chemicals and eroded soils to streams are the likely cause of these declines. Because of their intolerance to many forms of disturbance, lampreys are being used as biological indicators of healthy stream systems. Recent surveys in Minnesota have revealed that lampreys are still present at the majority of stream sites where they were reported in the past. We know for certain that some populations are smaller than they used to be, because we don't see as many spawners as we saw before. We lack good historical data for most stream populations, so we don't know if these small populations have always been small.
Projects aimed at improving stream habitats for game fish appear to benefit lampreys as well.
As people focus on better land management practices in watersheds throughout Minnesota, and as more people learn about native lampreys, I hope the outlook for the survival of these obscure but intriguing creatures will improve. Neal D. Mundahl is a professor in the Department of Biology at Winona State University.