Low-cost computer-assisted image analysis for fisheries research

Document Type

Article

Publication Date

1-1-1997

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 different (P = 0.80) from the number estimated with image analysis (430 ± 43). Also, total lengths were measured manually on 50 fingerling channel catfish and 50 fingerlings of the hybrid channel catfish × black bullhead Ameiurus melas. An image of each fish was also recorded for measurement by image analysis. Replicate sets of measurements were made by three individuals with different levels of experience with the computer system. The mean (±SD) of total lengths measured manually for the channel catfish fingerlings (242 + 33 mm) was not significantly different (P = 0.37) from the lengths determined by image analysis (237 ± 33, 235 ± 33, and 231 ± 34 mm). The mean of total lengths measured manually for the hybrids (157 ± 39 mm) was not significantly different (P = 0.98) from the lengths measured by image analysis (158 ± 40, 157 + 39, and 155 ± 39 mm). The availability of public domain software and inexpensive or commonly available input devices make image analysis more accessible to researchers. © by the American Fisheries Society 1997.

Publication Source (Journal or Book title)

Progressive Fish-Culturist

First Page

235

Last Page

240

This document is currently not available here.

Share

COinS