Reproductive success of individual razorback suckers in impounded backwaters

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

Year: 2012 (xliv)

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. This species has been heavily impacted by predation from a suite of non-native fishes, with no natural recruitment in Lake Mohave. The Native Fish Work Group has developed a conservation protocol where 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 for this plan, serving as mesocosms that would provide valuable refuges for conservation of this species. Given this strategy, it is important to obtain essential information for informed management of this species in such habitats. We explored the reproductive success of razorback sucker in ephemeral 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 in order 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, allowing for maintenance of high levels of variation found within this species.