Low-Cost Computer-Assisted Image Analysis for Fisheries Research

Abstract An image analysis system based on the Macintosh personal computer and public domain software (NIH Image, version 1.57) allows capture of digitized images for data analysis. Three techniques for image capture and aquisition of linear and area measurements from digitized images were tested: (1) estimation of egg size, (2) estimation of number of eggs or fry, and (3) measurement of fish length. For estimation of egg size, egg samples were taken by catheterization from two female channel catfish Ictalurus punclatus. Egg diameters measured manually (1,82 ± 0.27 and 2.59 ± 0.19 mm) were not significantly different (P = 0.08 and 0.20) from the diameters estimated with image analysis (1.92 ± 0.21 and 2.63 ± 0.17 mm). For egg counting, channel catfish eggs were hand-stripped into Hanks' balanced salt solution and divided into seven 15-mL aliquots. The number of eggs was determined manually and images were captured for analysis. The number of eggs determined manually (436 ± 41) was not significantly differ...