Gretchen Hansen

Declining Populations of Iconic Fish
1:20 pm
Wed October 22, 2014

Scientists Investigate How Walleye Are Faring in Wisconsin Lakes

Populations of adult walleye are declining at an average rate of two percent per year.
Credit Eric Engbretson / US Fish and Wildlife Service

Researchers at the Wisconsin DNR are looking for answers as to why walleye populations are declining in the state.

DNR Research Scientist Gretchen Hansen says adult walleye numbers are declining statewide by an average of two percent per year. 

“So there’s a lot of variability.  So in some lakes, populations are going up, but in the majority of lakes populations are going down.  And a lot of that is driven by failed recruitment, so failed reproduction.” 

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Going Against the Grain
4:51 pm
Tue November 12, 2013

Study Reveals Nuances of Aquatic Invasive Behavior

Invasive species like eurasian water milfoil can be a big problem.
Credit BerndH via Wikimedia Commons

We usually think of an invasive species as taking over its environment, at the expense its native counterparts.  

But a new study from the University of Wisconsin Madison’s Center for Limnology challenges that assumption.  It compiled survey data from a variety of studies on aquatic species, and finds that most of the time aquatic invasives keep a pretty low profile.  WXPR’s Natalie Jablonski sat down with Gretchen Hansen, lead author on the study.  

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