Post‐release movements and habitat use of robust redhorse transplanted to the Ocmulgee River, Georgia

Abstract

Abstract Robust redhorse Moxostoma robustum is an imperiled, potadromous fish in the south‐eastern USA. Initial recovery efforts have focused on supplementing existing populations and establishing refugial populations through extensive stocking programmes. However, assessment of the success of these programmes has not yet been conducted, and there are few reports evaluating the effectiveness of such programmes with other potadromous species. Radio telemetry was employed to assess the effectiveness of a stocking programme aimed at addressing whether stocked individuals would remain in an area free of introduced predators and ascertaining the ability of stocked fish to integrate into a resident population. Hatchery‐reared robust redhorse were captured from refugial populations established in other river systems and were transferred to the Ocmulgee River, Georgia where a population of hatchery‐reared individuals and an unknown number of wild fish reside. These transferred robust redhorse exhibited an exploratory phase for the first 3 months before adopting behaviour patterns, including spawning migrations, that were consistent with those reported for wild fish in other systems. However, some individuals seemed unable to locate suitable spawning habitat. Approximately half of the radio‐tagged fish remained within the area free of introduced predators. At least some radio‐tagged robust redhorse fully integrated into the resident population as evidenced by their presence in spawning aggregations with resident individuals. The effectiveness of a stocking programme is dependent upon the ability of stocked individuals to integrate into an existing population or replicate the behaviour and functionality of a resident population. Evaluations of stocking programmes should incorporate assessments of behaviour in addition to surveys to estimate abundance and survivorship and genetic assessments of augmentation of effective population sizes. Published in 2008 by John Wiley & Sons, Ltd.