Tales of Two Treasure Hunts
BY MARK STEINGRAEBER, LA CROSSE FWCO
The request for help from Nathan Eckert, mussel biologist at the Genoa National Fish Hatchery (NFH), came to the La Crosse Fish and Wildlife Conservation Office in Onalaska, Wisconsin later than usual this year.
Above normal rainfall in June kept water levels in many regional rivers bank-full, well into July. Levels now were dropping and the seasonal opportunity we eagerly awaited was here: spending a hot summer day in the cool Chippewa River to snorkel in search of hidden biological treasure … freshwater mussels!
But on July 12th, as we prepared to wade across the braided river to mussel beds on the opposite side of the channel, something seemed to be missing from similar efforts here in past years.
Q: Where’s that old sandbar?
A: Under a foot and a half of water!
Demand for electricity caused the hydropower dam miles upstream to release more water, increasing the river discharge nearly 50% overnight. We soon found this additional increase in water would require an exponential increase in our efforts that day. For example, we placed a greater than normal emphasis on keeping our heads above water to be sure our cross-channel treks remained an aerobic form of exercise.
Once having safely reached the opposite shore, we donned our masks and snorkels and began to search for mussels in shallow water near the bank. When this proved unsuccessful, we expanded the search area into deeper waters. Despite brilliant sunshine, bottom visibility in the arms-length deep, tea-colored water was poor and maintaining position was all but impossible in the swift current. The mussels were simply located beyond routine snorkeling depth.
Faced with the prospect of coming up empty handed, one by one we began to discard our snorkels, take large breaths of air, and repeatedly dive to the river bottom in a series of dim-lit, tactile adventures spent groping the sand for mussels as the current carried us body-surfing downstream.
Although more physically demanding, this collection method proved to be effective under the challenging conditions. A total of 13 gravid (pregnant) mussels (11 sheepnose, two black sandshell) were brought to the Genoa National Fish Hatchery that day for propagation activities and 16 hickorynut mussels were taken for other research projects.
Two weeks later on July 25th, we received another request from Nathan for help; this time things would be different. River stage dropped by two feet and discharge was half what it had been. Crossing the river was no longer the physical chore it had been and snorkeling conditions were ideal.
A total of 19 species were found in little more than one hour. These included the creeper, pink heelsplitter, white heelsplitter, pimpleback, monkeyface, three horned wartyback, pistolgrip, fatmucket, plain pocketbook, giant floater, wabash pigtoe, black sandshell, elktoe, deertoe, fawnsfoot, fragile papershell, and threeridge. More than 60 hickorynut were recovered for research purposes and a fraction of the 26 gravid sheepnose were transported to Genoa National Fish Hatchery for propagation of this federal-listed endangered species.
What a difference a little less water can make!