Photographic image analysis for morphometric studies of tilapia

Abstract

Biologists have long employed morphometry as a tool in identification, grouping of populations and stock identification of fish. For tilapias, studies have been made on the variability of morphomeric characters in Egyptian species (Libosvarsky and Bishara 1986). Truss morphometrics, where the body shape is divided into a series of 'cells' each of which contains information on the shape and size of the fish, were used by Brzeski and Doyle (1988) for Oreochromis mossambicuslurolepis hornorum sex differentiation. We have developed a computerized approach to the collection of morphometric data using image analysis and a digitizing tablet with 21 landmark points on tilapias. This technique provides accuracy, speed of sampling and a permanent record and is an alternative to measurements of live fish with calipers.