No Bones About It: Population Structure of Bonytail in High Levee Pond

Authors: Tiffany Love-Chezem, Ethan Rasset, Aaron Meuhler

Year: 2024

Abstract

Cibola High Levee Pond (HLP) is an isolated backwater on the Lower Colorado River (LCR). It has the oldest self-sustaining population of Bonytail Chub, Gila elegans, last stocked in 2005. The size structure and population size of Bonytail in the pond is variable year to year, and age structure has not been well studied. Population estimates were completed during the winter of 2024 and 1% of the population was sacrificed for the collection of otoliths and fin rays. Both were mounted in resin and cut using a high-speed isometric saw, aged independently by two biologist, and demographic modelling was completed via von Bertalanffy growth curves and catch curves. Comparison of otolith and fin rays found no agreement in ages. Indicating that the non-lethal method of fin ray aging is unlikely be a viable alternative to otoliths for Bonytail. Bonytail were aged as old as eight years, but year five was missing from our sampling. Understanding the population dynamics of HLP could lead to a better understanding of these species in the current occupied habitat in the LCR.