Once abundant throughout the Mississippi drainage, which includes the Chicago area, mudpuppy populations have declined or disappeared due to water pollution, sedimentation, collection for the biological supply trade and a tendency of fishermen to kill them because of misbeliefs that they are detrimental to sportfishing or are poisonous.
In Shedd’s backyard
One of Alicia’s research sites is within sight of Shedd, along the Monroe Harbor breakwater. She and her team began work in spring of 2014, while lake temperatures were still cool and the mudpuppies were active. To collect the secretive amphibians, they tether funnel-shaped minnow traps to roots, riprap and other cover along the break wall. In the beginning, they experimented with several enticements, including canned cat food, earthworms and shrimp to attract their nocturnal study subjects. Night crawlers did the trick.
Retrieving the traps, the researchers measure and weigh each animal and determine its gender. Then each mudpuppy is implanted with a passive integrated transponder, or PIT, tag, like those used for dogs and cats but much, much smaller. On future encounters with an individual, Alicia can use a scanner to read the mudpuppy’s identification number. By tagging the animals, Alicia can assess the population size and understand movement patterns of individual animals.
Before releasing a mudpuppy back into the lake, Alicia uses a syringe to gently flush stomach contents to discover what it eats. Prey identified in Monroe Harbor (Lake Michigan) mudpuppies included shrimplike mysids as well as an isopod and round gobies (an invasive fish).
Dogged research through winter
The amphibians’ fall breeding season offers Alicia more opportunities to sample areas along the lakefront. And “mudpuppying” in winter is especially productive.
Unlike other amphibians, mudpuppies are active during the coldest months of the year. Acting on reports from anglers of “fish with legs,” Alicia and her intrepid team trekked to a small lake on the Illinois/Indiana border, where they are working through the winter and into early spring.
Other than having to drill holes in the thick ice to sink their traps, their methods are the same as they collect data on these hardy amphibians.
The mudpuppy project is another facet of Shedd’s dedication to protecting the native wildlife that inhabit our lakes. The results of Alicia’s research will inform conservation and management strategies to protect this gentle, reclusive member of our local ecosystem.