Validation of Aging Tcchniques for Walleyes (Stizostedion vitreum)

from Munuscong Bay, MI

Michael Kaller
School of Science and Natural Resources
Lake Superior State Urnversity
Sault Ste. Marie, MI 49783



Abstract:	Scales and dorsal spine cross-sections are two methods used to age fish.
Although aging with scales is a widely utilized method, problems exist with this
procedure (Chilton 1986).Dorsal spine cross-sections have grown in popularity
because studies have demonstrated greater reliability in age estimates with this
method (Margenau 1982). The objective of this study was to determine if
differences existed in the estimated ages of fish a sample of walleyes (Stizostedion
vitreum) from Munuscong Bay by both methods. Chi-square analysis indicated a
significant difference (p=O.009) in estimated age. Additional analysis with a
paired t-test, as done in similar studies, also yielded a significant difference
(O.Ol<p<O.02). Due to a significant difference in the estimated age of walleyes
existing between the two techniques and aging with dorsal spine cross-sections
resulting in more accurate results, the dorsal spine cross-section technique
should be utilized as the aging estimator for walleyes in Munuscong Bay.

Selected References

Chilton, D. F., and H. T. Bilton. 1986. New method for ageing Chinook salmon
(Onchorynchus tshawytscha) using dorsal fin rays and evidence of its
validity. Canadian Journal of Fisheries and Aquatic Science. 43:1588-4594.

Margenau, Terry L. 1982. Modified procedure for aging walleyes by using dorsal
spine sections. Progressive Fish Culturist. 44:204.