Body Size Estimation and Identification of Twelve Fish Species Using Cleithrum Bones

Abstract

Diet evaluations are conducted to understand predator-prey dynamics of fish communities.However, unless prey items are extracted from fish immediately after consumption, items can beobserved at various stages of decomposition due to digestion. Thus, the ability to accurately measureor identify prey fish is difficult. Fortunately, some skeletal structures, such as the cleithrum bone,are not easily digested and remain in fish stomachs. Cleithra have been used to estimate the totallength of a fish by determining the linear relationship between the total length, horizontal length,or vertical height of a cleithrum against known-sized fish from which the structure was taken.We used linear regression to develop equations to estimate body size for twelve common foragespecies found in Oklahoma reservoirs using cleithrum bones. The relationships between total fishlength:cleithrum length (r2= 0.94-0.99), total fish length:horizontal cleithrum length (r2= 0.90-0.98),and total fish length:vertical cleithrum length (r2= 0.88-0.98) were significant. Additionally, we alsodescribed cleithrum characteristics for each of the twelve fish species, such that fish can be identifiedeven when prey items are heavily digested. When used collectively, the regression equations anddiagnostic features of cleithra will provide a more accurate description of fish diets and a betterunderstanding of predator-prey relationships.