Elasmo.Students's picture

Student Award Profile - Darcy Bradley

Darcy Bradley received the Samuel H. Gruber Presentation Award for the best presentation and the Jeffrey C. & Carol A. Carrier Poster Award for the best poster at the 2015 meeting in Reno, NV for her PhD research at the Bren School of Environmental Science and Management at the University of California, Santa Barbara with Dr. Steven Gaines.

Q. How did you get started in this field?

I was introduced to the field of shark research while working as a field researcher for a whale shark research and conservation organization in Western Autralia. In this role, I worked in direct collaboration with the Department of Environment and Conservation to ensure that our research program was addressing their management concerns. It is this critical and often undervalued link – between research and actual management – that interests me most and that my current research continues to address.

Q. Tell us a little about your award-winning research. What was the most important finding of your research?

A fundamental challenge of wildlife ecology is to understand what populations looked like before human impacts. This is particularly true for the marine environment, where humans have been aggressively removing species long before we began studying them. Population baselines are critical for addressing how much a system has been altered and what solutions may be viable to restore impacted systems. We have used the unique setting of Palmyra atoll, a U.S. National Wildlife Refuge in the remote Pacific that is one of the few remaining unfished coral reef ecosystems on the planet to address the baseline problem for sharks. Palmyra has been studied before and was the basis for a very high profile set of publications that concluded that historical shark populations were dramatically larger than current populations elsewhere in the world. These studies, however, were based on spatially limited data and sampling techniques with significant biases. We have taken the sampling of large, mobile predators like sharks to a new level by utilizing new analytical approaches that combine capture-recapture sampling, acoustic tracking, and relatively new spatial statistics in the form of spatial capture-recapture models. Our findings are striking – the prior studies greatly overestimated the number of sharks in a pristine coral reef setting. The implications of this work are potentially globally important in terms of helping understand how far current shark populations have fallen from their historical levels.

Q. What are your other research goals?

My dissertation research also examines how non-extractive human impacts affect shark behavior. Humans play a significant predatory role in terrestrial and marine ecosystems and anthropogenic fear effects have been recorded in a suite of systems across the globe. An open question is whether the mere presence of SCUBA divers can have long-term effects on animal behavior in the marine environment. We use baited remote underwater video surveys (BRUVs) to examine the spatial distribution and abundance of reef sharks at heavily dived and undived sites at Palmyra atoll, where we can isolate and quantify the behavioral response of reef sharks to human activities in the absence of fishing.

Thanks and good luck Darcy.