Analyzing translocation success from sporadic monitoring data using survival analysis: Lessons from the Gila Topminnow (Poeciliopsis occidentalis).
Sheller, Frances1, Fagan, William1, Unmack, Peter2, 1 University of Maryland, College Park, College Park, Maryland2 Arizona State University, Tempe, Arizona
ABSTRACT- Anthropogenic degradation of natural habitats is the major factor in the recent global increase in species extinction rates and reduction in biological diversity. The development of land and water resources caused the fragmentation of local populations, acting to isolate species and increase their vulnerability to extinction. Conservation translocations, the intentional release of captive-bred individuals in an attempt to establish, reestablish, or augment a population, have become an important management tool in the effort to counteract losses to extinction. Despite their frequent use and prominence in many species recovery plans, translocations have demonstrated limited success in the creation of sustainable populations. Understanding the factors that influence successful translocations is imperative to reach conservation goals, and the study of systems with extensive translocations histories can offer these important insights. The Gila topminnow (Poeciliopsis o. occidentalis) provides such an opportunity, with over two-hundred recorded stockings since 1973. Using this dataset, we generated a long-term viability analysis of the recorded translocations, and quantified the relative importance of stocking factors on population persistence. The survival analysis of the examined translocated populations demonstrated that stocking factors such as month stocked, the presence of non-native species, and genetic origin of fish stocked all significantly affect population persistence and subsequently, translocation success. The identification of factors that significantly influence the success of translocation attempts will lead to the creation of improved species conservation recommendations. More generally, these results may be used to answer larger ecological questions relating to why fragmented populations go extinct and what factors most influence extinction risk.
Key words: Poeciliopsis occidentalis occidentalis, translocation, Gila topminnow dataset
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