Oxbow Restorations for Topeka Shiner (Notropis topeka) Recovery: Defining Success

Abstract

Within the Great Plains region of North America, oxbow wetlands were lost as streams were channelized and straightened to allow for agricultural use of the landscape. Topeka Shiner, which rely on these oxbow wetlands, have declined in abundance, currently occupy 20% of their historical geographic range, and are now an endangered species. A large emphasis has been placed on restoring oxbow wetlands to recover Topeka Shiner populations. As the number of oxbow restorations has increased, so has the number of monitoring projects focused on these habitats. Currently, conservation practitioners rely on the presence of Topeka Shiner to determine the success of an oxbow restoration. Given the rarity of the species, this method is likely ineffective. Within this study we attempt to create a model that can be used to determine the success of an oxbow restoration that will benefit the Topeka Shiner without relying on the presence of the species in the wetland. We used multiple fish community metrics and modelling strategies to determine the best model for predicting Topeka Shiner CPUE and presence/absence within oxbows. We determined that the top models were ineffective at predicting Topeka Shiner CPUE and presence/absence. Our findings illustrate the random nature by which fish communities become established within oxbows, and the island-like nature of oxbows in terms of how fish communities may become established and change over time. These findings indicate that the success of oxbow restoration for Topeka Shiner needs to be defined at a larger scale than for individual oxbows. Furthermore, our findings corroborate the inability of previous studies to determine reproducible associations of Topeka Shiner with various fish community metrics.