A Continued Assessment of the Reproductive Success of Razorback Sucker Stocked in Ephemeral and Permanent Backwaters of Lake Mohave.

Authors: Melody J. Saltzgiver, Thomas F. Turner, Thomas E. Dowling, Paul C. Marsh

Year: 2013 (xlv)

Abstract

The endangered razorback sucker is indigenous to the Colorado River system. This once widespread species has become rare, with the largest aggregation currently found in Lake Mohave, Arizona and Nevada. This species has been heavily impacted by predation from a suite of non-native fishes, with no natural recruitment in Lake Mohave. The Lake Mohave Native Fish Work Group has developed a conservation protocol whereby wild razorback sucker larvae are collected from the lake, and reared in protective custody until they are large enough reduce the incidence of predation. Off-channel ponds and impounded backwaters are critical components of this plan, serving as mesocosms that would provide valuable refuges for conservation of this species. Given this strategy, it is important to obtain fundamental data for informed management of this species in such habitats. We explored the reproductive success of razorback sucker in ephemeral and permanent backwaters of Lake Mohave. Fin clips were taken from all adults stocked into study sites and genetic profiles were generated using 14 microsatellite markers. During spawning and in the subsequent autumn, samples of offspring were gathered from each site, and genetic profile generated for each. Profiles of offspring were compared to adults to identify parents of individual larvae or juveniles. There was considerable variability in levels of productivity among sites, but given the right conditions, many adults can contribute to larval production using backwater habitats, thus allowing maintenance of high levels of variation found within this species.