Mussel up

(First published in the June 6, 2019 issue of City Pages)

Workshop helps identify, rescue mussel species on the Wisconsin River during drawdown

Mussel workshop Scholfield Park

Mussel workshop Scholfield Park

DNR Conservation Biologist Jesse Weinzinger (brown shirt, sunglasses on his cap) helps ID mussels at a workshop to rescue mussels along the Wisconsin River.

Volunteers who signed up for a mussel workshop in Wausau Saturday, June 1, learned about the curious little critters during survey/rescue work at the Scholfield Park boat landing.

With Department of Natural Resources conservation biologist Jesse Weinzinger leading, the group learned about mussel biology and how to identify them. They set out in kayaks, chest waders and some in just sneakers to paddle near or walk the shore and collect as many mussels as they could in buckets and mesh bags. The critters were identified, counted and tossed into deeper sections of the river to give them a better chance of surviving the drawdown.

The drawdown was not as far along as hoped because of the rains that keep falling, but the group still found plenty of mussels.

Their identification sheets had images of eight types of mussels they might find, but Weinzinger says they found 11 types. “We were pleasantly surprised,” he says.

They did not find any endangered species of mussels, but found black sandshell mussels, a species of concern. They also found fatmuckets, he says, a good sign because they are one of the most sensitive animals to ammonia and are “one of the first to go if you have a lot of runoff from farm fields,” Weinzinger says.

Mussel workshop Scholfield Park

Mussel workshop Scholfield Park

A five-year-old fatmucket (scientists determine their age by rings on their shells, like trees) and a very young mussel of the same species.

Weinzinger thought the mussels would have been wiped out because of high pollution levels on the Wisconsin River years back. They are sensitive to pollution and sedimentation, but Saturday’s volunteers found good numbers of them, including species the DNR’s mussel monitoring program staff did not know live here.

Mussels of various sizes are a food source for crayfish, raccoons, otters, muskrats, egrets and herons, Weinzinger says. The birds eat them shell and all, relying on strong digestive fluids to soften and dissolve the shell. “They don’t break it apart,” he says, “they let their body do the work.”

An adult mussel can filter several gallons of water. Weinzinger says there are streams where the beds of mussels are so massive that water quality downstream is measurably better than upstream. “That’s a lot of free water filtration,” he says.

The mussel’s reproductive cycle, which relies on fish, demonstrates an interesting way they fit into the eco-system. When a female is ready to reproduce, she opens her shell slightly to expose an appendage. It’s a trick appendage, though, looking like a small minnow. When bitten by a fish like a bass, it squirts out a cloud of thousands of young and small mussels that are hard to see with the naked eye. The stream of tiny mussels go into the fish’s mouth, clamping like miniscule Pac-Man creatures to its gills where they find a blood supply they can live on for long enough to grow a shell.

When they’re large enough in a few weeks, the mussels just drop off the gills and sink to the bottom. If they land in a hospitable spot, they survive. The fish is not harmed. Readers can see the process by searching “Natural Fish Lure” on YouTube; the first result is the right video.

Weinzinger says future workshops will probably be elsewhere in areas where there’s a drawdown, but if people want to receive the mussel monitoring newsletter, they can email him at [email protected].