A Critical Study of the Relation between Body Length and Several Scale Measurements in the Smallmouth Bass, Micropterus dolomieu Lacepede

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Abstract
The bodyscale relationship was detd. and the relative efficiency of different scale measurements in estimating body length in smallmouth bass was measured. Anterior radius, anterolateral radius and width of the scale were compared. The practice of taking "key" scales was compared with the more customary procedure of taking several scales from a specific area. The relative efficiency of predicting body length from scales taken from the region in which they 1st arise was compared with those taken in the pectoral region. The bodyscale relationship was found to be curvilinear, chiefly as a result of the faster proportional growth of the anterior radius in the scales of the smaller bass. Data above a body length of 15 cm. do not appear to depart seriously from a straightline relationship. Regression lines fitted to the data for lengths below 15 cm. intercept the length axis very close to the observed body lengths of 2.0 [plus or minus]0.1 cm. at scale formation. The statistics of multiple regression were found useful in making critical quantitative comparisons. Analysis indicates that there is no evidence to suggest that taking a key scale, or using scales from the area where they 1st arise gives any added precision in predicting previous body lengths. The relative efficiency of the anterolateral radius and width is less than the anterior radius in predicting body lengths but significantly so only in the width. Body lengths backcalculated using caudal scales are lower than bddy lengths calculated from the pectoral scales. Lengths calculated from the standard and key scales or from the scale measurements of anterior radius and anterolateral radius are not biased in either direction.

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