Translocation and Reproductive Benefits to a Highly Endemic and Endangered Species, the Banbury Springs Limpet, Idaholanx fresti (Mollusca: Gastropoda)

Abstract

We have monitored four isolated populations of the endangered freshwater Banbury Springs limpet for eight or more years. One of these populations consistently exhibited low numbers and very limited recruitment. In an effort to increase its size and reproductive vigor, we translocated 19 limpets from a large, robust population to the smaller, declining one (focal population). This translocation effort was carried out along with a small-scale habitat management effort. Post-translocation monitoring has seen the focal population increase by up to 900%, with an increase in reproduction from 6% to 33–55% annually. Limpet densities in the focal population also have increased from 5.5 m–2 to 43 m –2 post-translocation, reaching densities seen in more stable populations. The augmentation of additional individuals, in addition to ongoing habitat management efforts, likely played an important role in the observed increases. The observed recruitment also suggests some level of increased genetic vigor following the translocation, but we lack the data to fully support a genetic rescue effect. Although translocation and augmentation of isolated and declining populations should be approached cautiously, our results support a growing body of literature that suggests the shortcomings associated with these techniques may have been overstated in the earlier literature. If done properly, their use can provide important conservation gains for small and isolated populations of sensitive species.