Reproductive success of Bonytail (Gila elegans) reared in off-channel habitats

Authors: Megan Osborne, Alyssa V Sanchez, Thomas Turner

Year: 2016 (xlviii)

Abstract

Bonytail (Gila elegans), once a prominent species in the Colorado River, has experienced the most dramatic declines of the Colorado’s four ‘big river’ fishes due to the introduction of non-natives, installation of mainstem dams, and water development. Bonytail is listed as an endangered species, is considered functionally extinct in the wild, and efforts to reestablish a population of Bonytail have been unsuccessful. An alternative management strategy was proposed in 2003; utilizing isolated backwaters for reproduction and rearing of several species, including Bonytail. It is critical to monitor and understand the effects of democratic factors, including breeding behaviors, on genetic diversity in fish reared in isolated habitats. In 2016, Nevada Egg and Nort h Nine Mile backwaters, were stocked with 100 male and 100 female adults. Larvae and age-0 fish were collected over the course of the summer. All fish were genotyped at 18 microsatellite loci to facilitate parentage analysis, obtain estimates of genetic diversity and effective size. Results included that 77% of males and 64% of females contributed progeny, and the majority of these individuals mated multiply. Genetic effective size was 134 in Nevada Egg, and overall, results were similar to that seen in 2014 and 2015.