Comparison of manual measurements and computer-assisted image analysis in fsh morphometry

Abstract

Fish usually have a simple body shape and many morphological characters can be easily obtained by 2-dimensional imageanalysis. Measuring errors are ofen analyzed using data from several researchers or repeated measurements, but the testing of accuracyand repeatability based on diferent methods has rarely been examined. Here we report the comparison of manual measurements usingProma 150D digital calipers and computer-assisted image analysis in LUCIA sofware to evaluate the accuracy of both methods andthe suitability of digital images for exploration of fsh morphology. Eighteen morphometric characters of 20 specimens of Prussian carpwere examined by 2 researchers. The mean of the relative bias within and between researchers separately for the manual and computer-assisted methods (expressed as a percentage of a character s value) varied from 4.27% to 9.48%. Comparison of interresearcher resultsusing digital caliper, interresearcher results using LUCIA, intraresearcher results using digital caliper, and the 2 methods using manualcaliper and LUCIA revealed signifcant differences in several characters. Only testing of intraresearcher relative bias using LUCIAshowed no signifcant difference.