A study of the Iowa River shows some mixed results for the population of freshwater clams or mussels in the waterway. The Iowa DNR annually conducts what it calls a “Mussel Blitz” on one of the state’s waterways. Spokesman Joe Wilkinson says around 50 people participated this year. “Some are biologists, some are paid workers from the U.S. Fish and Wildlife Service…a few biologist from the DNR, but a lot are volunteers as well, students from some of the different universities…. they are kind of mussel fans and they want to do the best that they can to try and keep track of where the mussels are in Iowa,” Wilkinson says.
The have divers that go into the deep water, but most move along the shallow areas counting the clams. “A lot of the other people are what we call polliwoggers, where they will basically get down on their hands and knees and they are in water up to their shoulders grouping through the muck and the sand and the gravel trying to come up with freshwater mussels to see what kind of species they are,” Wilkinson explains.
All the floating in the water and digging in the muck is an effort to build a history of the population in the state. “We got about 1,500 of these freshwater clams, these mussels. About 20 different species, which sounds like a lot, but historically Iowa had 54 species and now a dozen have disappeared, we haven’t seen those in decades,” Wilkinson says.
There was a positive find. “Among those mussels were half a dozen Higgins’ eye mussels, which is a federally endangered species,” Wilkinson says. The find of the Higgins’ eye mussels shows a restocking effort has a foothold. “Crews that were out five, six, seven years ago actually planted some of these tiny little Higgins’ eye mussels in the river and they are finding them now in the adult stage — three or four inches across,” Wilkinson says. “Which means that they are growing and that they are adults. And that’s always a good sign too.”
Why all the concern about the clams? “Mussels are a real good indicator of the health of the river,” according to Wilkinson. “They have also co-evolved with fish…so if you’ve got a good mussel population you are pretty assured of having a good fish population as well, and any angler is going to appreciate that. The better the water quality, the more mussels there are in that water.”
Wilkinson says they are building information on the mussels, but says it’s too earlier to put a grade on how well they are doing. He says the study of them isn’t that old, but they do know that the mussels in the rivers have gone downhill over the last 100 years. Wilkinson says there is still a lot to learn about the mussels, such as how things like flooding and extreme cold impact the populations.