Field Notes
U.S. Fish & Wildlife Service
Field Notes Entry   
Columbia FRO Compiles Missouri River Chub Ages
Midwest Region, December 31, 2006
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Columbia FRO Biologist Jennifer Johnson and Biological Science Technician Lee Erickson are nearing the completion of a three year Macrhybopsis spp. chub ageing project. Over 1,350 chubs were collected throughout the Missouri river from Montana to Missouri over three seasons for age and growth analysis.


Johnson and Erickson aged each scale independently by placing the scales between two glass slides and examining them through a microfiche reader. In instances where the assigned age was different between the two readers, scales were read a second time (by both readers).


After the scales had been aged, Biological Science Technician Brian Elkington measured growth between the scale annuli using Image J software which allows a Scion Color Digital Camera connected to a dissecting scope to capture images of the scale and display them on a computer screen.


Age and growth data will be summarized in a three year report for the Missouri River Pallid Monitoring program. Growth differences between years and throughout the River will give biologists information related to environmental factors affecting native river species.

Contact Info: Larry Dean, 612-713-5312, Larry_Dean@fws.gov
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