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Mudpuppy study yields new discoveries below the surface

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Hanson baits a mudpuppy trap with minnows to attract the carnivorous salamanders for study. (Press photo by Molly Moser)

By Molly Moser

An ongoing study of Iowa's largest salamander, the mudpuppy, has revealed much higher local populations than previously thought. 

Last October, animal survey specialist Jeff LeClere visited Guttenberg to begin the study with DNR fisheries technician Kevin Hanson. Mudpuppies have been moved to the top of the priority list in Iowa due to the lack of knowledge about this threatened species. One mudpuppy was found in Bluff Slough after a 2008 train derailment near Guttenberg, so some of the resulting mitigation funds are being used for the mudpuppy project. The study entered its second year this fall as Hanson set the first 20 traps of the season. 

Hanson said last year’s observations yielded new discoveries, some of which helped him choose where to place live traps for this year’s study. “Most of what people thought about mudpuppies is that they were a shallow water creature,” he said. However, last year mudpuppies were discovered at the bottom of 20-35 foot holes. “They were thought of as territorial and solitary, but we’ve seen them in big numbers in one spot.”

The technician continues to be amazed by the things he’s learning. The 2015 study yielded 51 live specimens that were photographed, tagged, and genetically analyzed by a lab at the University of Eastern Michigan. Mudpuppies in pool 11 are being compared with populations in Vermont, Ohio, and Michigan, and genetic comparisons will eventually be made between mudpuppies discovered on the Wisconsin side versus the Iowa side of the Mississippi River. The majority of the mudpuppies found during last year’s study were genetically similar to the Minnesota population, but four individuals were genetically different – an entire population unique to just this area. 

The illusive necturus maculosus is extremely slimy, with lidless eyes and external gills. It has a head like a dragon, the body shape of a fish, and sports four stubby legs with four toes on each tiny foot. It can grow to be nearly 20 inches long and can live up to 20 years. Mudpuppies breed in the winter but don’t lay eggs until May or June. Arrangements of flat limestone or plywood have been found to attract female mudpuppies, who lay their eggs on the bottom side of such structures. The farthest movement by a single individual trapped in the ongoing study is 100 meters.

LeClere and Hanson presented the results of the first year’s study at an Iowa Herpetologist Society meeting in September, and there learned of a new tracking device that may help them follow the movements of mudpuppies underwater. “To track a fish, you perform a surgery and implant the transmitter inside,” Hanson explained. The large size of the battery pack required by such tracking devices has thus far prohibited tracking of smaller amphibians, but a presentation on radio tracking tiger salamanders with internal transmitters gave Hanson and LeClere hope. “Because of what they did, we’re optimistic about being able to give it a try,” Hanson told The Press. 

Mudpuppies are an important part of the underwater environment for several reasons. Some scientists suspect the presence of mudpuppies may be an indicator of good water quality, as they avoid areas of high siltation. Even more importantly, these amphibians are the only host for the salamander mussel, carrying around the mussel larva in their gills for several weeks. Without mudpuppies, this species of mussel would be lost entirely.

In spite of decreasing air and water temperatures, this time of year is best for catching mudpuppies. “Every other decent-minded reptile and amphibian are in hibernation right now, but mudpuppies like cold water,” Hanson said. Last year, he netted them from October until two days before Christmas. “They are most active in the winter, and are mostly nocturnal,” said LeClere. “They breed midwinter, eat midwinter, and all of this is happening completely underwater. People are not seeing it.” Thus, ice fishermen are more likely to catch the cold-loving amphibians than any other fishermen.

Fishermen who catch a mudpuppy this winter are asked to contact Hanson at 563-252-1156.

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