ABSTRACT

Sheller, F.J., W.F. Fagan , and P.J. Unmack. 2006. Analyzing translocation success from sporadic monitoring data using survival analysis: Lessons from the Gila topminnow ( Poeciliopsis occidentalis ). Ecological Applications 16(5): 1771–1784.

Translocation, the intentional release of captive-propagated and/or wild-caught animals into the wild in an attempt to establish, reestablish, or augment a population, is a commonly used approach to species conservation. Despite the frequent mention of translocation as an aid in threatened or endangered species recovery plans, translocations have resulted in the establishment of few sustainable populations. To improve the effectiveness of translocation efforts, it is essential to identify and adopt features that contribute to successful translocations. This study analyzed 148 translocations of the endangered Gila topminnow ( Poeciliopsis occidentalis ) to identify various factors that have significantly influenced translocation success. We quantified success as the “persistence time” of translocated populations, and used survival analysis to interpret the role of several factors. These factors include season in which the fish were translocated, habitat type of the translocation site, and genetic origin of the fish stocked affected persistence times of translocated populations. In general, factors associated with stocking, the population stocked, and the site of translocation can significantly affect the persistence of translocated populations and thus increase the probability of translocation success. For Gila topminnow, future translocations should be undertaken in late summer or fall (not early summer), occur into ponds (not streams, wells, or tanks), and should generally utilize individuals from genetic lineages other than Monkey Spring. For other species, a key lesson emerging from this work is that translocations need to consider carefully the life history attributes for each translocated species.