Date of Award
Level of Access
Master of Science (MS)
Ecology and Environmental Sciences
Sandra de Urioste-Stone
Second Committee Member
Third Committee Member
Lead poisoning from ingested fishing tackle is a well-documented conservation concern for adult common loons in the Northeastern United States. To mitigate this issue, the state of Maine began implementing restrictions on lead tackle use in 2002, with new legislation added in 2016 and 2017. In addition to legislative action there have been various non-regulatory strategies employed in Maine to help raise awareness, such as the Fish Lead Free campaign. Human behavior is the root cause of lead fishing tackle in aquatic environments, and also can determine the success of legislative and educational efforts. Measuring underlying factors that influence behaviors, such as values and trust, can help predict the efficacy of these efforts. We developed the following interdisciplinary study with two overarching goals: (1) to document the number of common loon adult mortalities resulting from lead poisoning; and (2) to measure factors that influence the risk perceptions of Maine residents regarding lead fishing tackle toxicity. We conducted necropsies on 480 adult common loons recovered in Maine between 1990 and 2016. Direct, anthropogenic causes of death accounted for 53% of all adult common loons necropsied. Overall, the main known cause of death in these loons was lead poisoning (25.2%) followed by trauma (20.6%), but analyses of causes of death over time determined that lead-related deaths decreased and trauma-related deaths increased over time. In addition, we surveyed 280 Maine residents in order to determine the psychological determinants of risk perceptions regarding lead fishing tackle toxicity. We found that risk perceptions were positively influenced by biospheric values and negatively influenced by social trust. Biospheric values, social trust, and risk perceptions were significantly different between Maine Consumptive and Non-Consumptive recreationists responding to our survey. The thesis concludes with a convergence of our findings from both biological and social science components. We found that lead mortality in adult common loons is decreasing, and anglers reported using lead fishing tackle less frequently over the last 5 years. The majority (75%) reported they never or almost never used lead fishing tackle in 2016, with the primary reason indicated for reducing lead tackle use was common loon conservation. Our work highlights the need for transdisciplinary studies to fully understand complex conservation issues.
MacDonald, Brooke S., "Lead Poisoning in Maine's Common Loons: Examining Biological and Social Dimensions" (2018). Electronic Theses and Dissertations. 2923.