The Aging of Two Madtom Catfish Species From a Southwest Missouri Stream

Date of Graduation

Spring 1996

Degree

Master of Science in Biology

Department

Biology

Committee Chair

Daniel Beckman

Abstract

Accurate techniques for age estimation of fishes are essential for determining the effects of resource management and to answer other life-history questions. Validation of an age estimation technique is important to insure that age is not over-or under-estimated. In this study two species of madtom catfishes, the slender madtom (Noturus exilis) and the Ozark madtom (Noturus albater), were aged using pectoral spines and otoliths. Validation was provided using marginal increment analysis, a technique which monitors the seasonal progression of otolith annulus formation in the population throughout the year. Spine age estimates were compared to otolith age estimates for each individual. Length versus age regressions and age-frequency distributions were compared between the two species. Marginal increment analysis data suggested that annuli formed concurrently in the otoliths of both species between the months of August and December. There is high variability in length at a given age, making otoliths a more reliable means of age estimation for these two species than length-frequency analysis. Analysis of Covariance showed that there was no significant difference between the age-length regressions of these two species. A Komolgorov-Smirnov test indicated that there was no significant difference between the size structures of the two populations, however there was a significant difference between the age structures of the two populations at the 0.05 level. Low variation among three independent otolith readings suggests that the otoliths of these species provided precise age estimates. The precision of spine age estimates was very low, suggesting that spines are an unreliable method for age estimation of these species and tended to underestimate age by at least one year.

Subject Categories

Biology

Copyright

© Lisa Kay Kiner

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Dissertation/Thesis

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