An analysis of ecological conditions and release procedures to guide reintroduction efforts for the Eastern Sand Darter (Ammocrypta pellucida) in Canada

Abstract

To address recent losses in freshwater biodiversity, reintroductions are becoming increasingly common as a tool for the conservation and rehabilitation of target species. As historically underrepresented approaches for fishes, many reintroduction projects have been unable to establish self-sustaining populations, due at least in part to an underappreciation of the stressors associated with the reintroduction process. Two elements that have a measurable influence on the probability of successful outcomes in reintroduction programs are the ecological conditions of the release habitat and the transport and release methods employed. The Eastern Sand Darter (Ammocrypta pellucida) is a small, benthic freshwater fish species that is threatened in parts of its range in Canada, and reintroduction has been proposed as a key component of its recovery strategy. To support the reintroduction of this species to Big Otter Creek in Ontario, Canada, I first assessed the environmental conditions and fish community assemblage along the length of Big Otter Creek to characterize reintroduction habitat. By considering factors known to influence Eastern Sand Darter persistence, including substrate composition and the presence of invasive species, I was able to identify a set of release sites that are likely to provide the best conditions for establishment. I then analyzed the influence of a simulated transport event on behaviour, and investigated whether the provision of in-river acclimation (i.e., soft-release) enclosures can promote recovery from transport stress. I found that transport stress did not influence behaviours related to activity level, space use, substrate preference, burrowing activity, response to a simulated predator, or swimming performance. I also found no differences in behaviour between control (non-transported) fish and those held in soft-release enclosures for 24- or 48-hours after transport. Some behaviours, however, differed between seasons (summer vs. fall). I conclude that Eastern Sand Darter may be behaviourally resilient to the effects of transport, particularly when conditions are ideal, and that traditional release methods with no acclimation period (i.e., hard-release) may be suitable for this species. Overall, my thesis contributes knowledge directly to reintroduction planning for the Eastern Sand Darter, while also more generally providing information on behaviour and responses to transport stress in conservation-relevant, small-bodied fishes.