Ruffe spines used to determine age. - FWS photo

Ashland FRO provided 200 frozen ruffe specimens in a cooperative research project currently in progress with Northland College. 

Under the guidance of  Dr. Derek Ogle, Department of Mathematics, Northland College senior, James Junker, is studying aging methodology on the invasive fish, Eurasian ruffe, for his required senior project. 

Dr. Ogle studied thousands of ruffe while interning for the Service's Lake Superior Biological Station. 

A growth ring called an annulus is produced each year on the scales, spines, and otoliths (inner ear) of fish, and the age of a fish is estimated by counting the number of annuli present.  Junker is assessing aging techniques utilizing the scales, spines, and otoliths of ruffe in order to determine the most accurate and efficient method for aging ruffe. 

In ruffe, the annuli are most easily identified in spines, but preparing spines to obtain a cross-section can be labor intensive.  Junker is currently experimenting with various techniques that are more efficient for extracting the cross-section of a ruffe spine. 

As requested by the Ashland FRO, Junker is also recording other data from the ruffe specimens including length, weight, sex, and maturity.