Researchers recently took to the water in the Wapsipinicon and Mississippi Rivers to do a census of sorts of the mussel populations. D.N.R. fisheries biologist, Scott Gritters, says they found 10 species of mussels in the Wapsie.
“The mussel population is low I would say in the Wapsie, but there’s pockets that have incredible density and diversity, but those pockets are miles apart from each other,” Gritters says. “We see that quite a bit on our inland rivers, but the Wapsie does have some exceptional pockets.”
He says dams on the river are part of the reason for the pockets, as fish can’t carry the larvae of the mussels upstream. Gritters says they have stocked some Higgins-eye mussels there and found they are growing there, which is good. The Mississippi River survey is the first there since 2005. They surveyed one area above Bettendorf near Pool 15 and found the site sits between two creeks and had a population of 200 some mussels. Most of them were young mussels.
“To see that many juveniles means I think that the population crashed in that area and is now rebounding. We didn’t see many adults, but we did see 22 species of mussels in there — which is also good,” Gritters says. He believes the population may’ve been impacted by an infestation of the invasive zebra mussels. They also survey and are near Pool 14. “That site, there was one really nice pocket of mussels there. A lot of site was sandy and not a lot of mussels of at all. But it was still neat for us to survey that area,” Gritters says.
The waters of the state used to be full of mussels, but they died back and Gritters says the effort to improve their populations continue. He says they are important to the waterways. “They filter the green stuff that you see in the water — the algae — out of the water. They’re kind of like trash compactors, they filter the water and they filter incredible amounts. Each of them filters gallons and gallons of water each day,” Gritters says. He says that water filtering of algae has a benefit for other wildlife. Gritters says the mussels squeeze the algae into a ball and then kick out a pellet. Fish will sit behind the mussels and eat the pellets. Gritter says the mussels are just good for the overall health of the water.
“If you are ever on a true mussel bed where there’s a lot of live shells and a lot of dead shells, you start flipping those shells over and there’s almost a crayfish under every shell. So, it’s a living ecosystem,” Gritters says. He says many of the major walleye spawning areas are in mussel beds on the Mississippi River. Gritters says overall the mussel populations are holding about the same as they were last year.