To find the answers, Solomon literally put the fish under a microscope. Using tissue samples, he found chemical “signatures” that can be used to tell the river-run fish from the existing lake-run populations as well as reveal what they eat and answer other important ecological questions.
Before runoff, siltation, dams and other manmade impacts made the spawning streams impassable and unlivable for whitefish (and other fishes), this important species provided what are called ecosystem services, helping to renew inland waters each year with nutrients that benefited plants and animals. Thanks to the Clean Water Act of 1972, water quality might have finally improved enough to make spawning possible again in these tributaries. With what Solomon and his research partners discover, critical habitat can be restored and managed to help ensure that these river-run populations thrive.
If you unbuild it, will they come?
Solomon’s second project was a study of the effects of recent dam removals on local fish communities in a Lake Michigan tributary. He was especially looking at migratory northern pike and suckers.
The lowermost dams on Duck Creek, in northern Wisconsin, were removed in 2012. Dam removal can be economically, politically and ecologically controversial. The changes to aquatic ecosystems can be immense as natural water flow is restored after decades.
Working with two years of data on fishes in Duck Creek collected by UW−M partners before the dams were removed, Solomon had a unique before-and-after perspective. He investigated whether migratory fishes will exhibit established patterns of movement or use the newly opened habitat farther upstream for spawning. He also looked at changes in fish biodiversity, habitat and survival rates of the year’s young. In the second season, Solomon included gars and bowfin in his data collection. He was also alert for less welcome fishes. Just as dam removal can benefit native migratory species, it can also be a gateway for invasive migratory species to expand their territories.