PhD Oral Exam - Andrew Harbicht, Biology
When studying for a doctoral degree (PhD), candidates submit a thesis that provides a critical review of the current state of knowledge of the thesis subject as well as the student’s own contributions to the subject. The distinguishing criterion of doctoral graduate research is a significant and original contribution to knowledge.
Once accepted, the candidate presents the thesis orally. This oral exam is open to the public.
With the ever-increasing number of species and populations impacted by human activities, the need for human involvement in their maintenance and/or conservation has grown in turn. This involvement increasingly takes the form of re-introductions or relocations to supplement populations in decline or that have been lost. As a result, reintroduction biology has become a quickly growing field in biology that attempts to answer the many questions related to reintroductions such as when and how best to release individuals into the wild, at what age should they be released, and in what situations is the release of new individuals sufficient to establish new populations. To advance our understanding of species reintroductions and address some of these questions in situ, adaptive management experiments and new techniques were developed for the reintroduction of Atlantic salmon to the Lake Champlain basin. By comparing long-term survival, spawning returns, and dispersal rates among alternative captive rearing and release methods, I assessed the suitability of methods commonly employed in salmonid reintroductions at re-establishing self-sustaining populations and meta-population structure. Concurrently, to address how changes in the species composition of Lake Champlain have affected the ability of reintroduced salmon to establish themselves, radio telemetry was employed to monitor spawning migrations through a challenging section of a tributary to Lake Champlain. In doing so, new transferrable radio telemetric techniques for continuous fine scale monitoring were developed. Comparing alternative rearing/release techniques to the standard method of producing one-year-old smolts for release, several significant trends were apparent. First, while fry (age 0+) releases resulted in dispersal rates consistent with Atlantic salmon meta-populations, they also produced significantly fewer spawners than most yearling releases. Second, all three alternative yearling rearing/release methods reduced straying rates relative to standard methods. Third, while advancing release dates lowered survival relative to standard procedures, using ambient water temperatures prior to release significantly improved both survival and spawning returns. Once released, growing salmon fed on alewife, an invasive prey species containing thiaminase, which lowered thiamine levels among mature adults, potentially impacting energy levels and swimming performance. At a challenging section of the Boquet River, we detected a significant effect of this thiamine deficiency on both upstream and downstream movement as well as a positive effect of thiamine injections on these movement rates, particularly among male salmon. To confirm this, however, a new telemetric technique was required. We therefore developed a technique that successfully estimated the location of tagged salmon to within several meters using readily available equipment and statistical models. Overall, these results will assist with the reintroduction efforts in Lake Champlain and are highly transferrable to the reintroduction/supplementation of other at-risk or extirpated populations. The methods developed below are readily implementable and provide positive returns on investment, both over the short- and long-term, while representing a step forward for the reintroduction of species of high economic, social, and ecological importance.