An Integrative and Interdisciplinary Approach to Shark Conservation: Policy Solutions, Ecosystem Role, and Stakeholder Attitudes

of a dissertation at the University of Miami. Dissertation supervised by Dr. Neil Hammerschlag No. of pages in text: (258) Many ocean ecosystems and the wildlife inhabiting them face significant anthropogenic threats. These environmental problems can result in negative impacts on the people who depend on these ecosystems for food and employment. Since human activities are the cause of many of these conservation issues and humans may be negatively impacted by them, the study of marine conservation biology requires an interdisciplinary approach incorporating methods from both the natural and social sciences. Scientific research and advocacy can interact with each other and influence environmental policy change through several processes, which may vary among conservation issues. A greater understanding of these interactions, which can be visualized through a conceptualized reactionary pathway, can result in more successful future environmental policymaking efforts. These processes and interactions have not yet been thoroughly studied in the context of shark conservation. Research priorities that have been established for shark conservation include determining the policy solutions that can most effectively protect sharks, improving our understanding of the ecosystem role that sharks play in the marine environment, and assessing stakeholder knowledge of and attitudes towards these and other research priorities. To address these knowledge gaps, I conducted an interdisciplinary dissertation with the overall goal of assessing how scientific research, public concern and advocacy, and policy change interact within a in the context of shark conservation research priorities. First, I reviewed the literature on shark conservation and management policies, which allowed for subsequent in-depth analysis of stakeholder preferences towards each policy. This review summarized the benefits, drawbacks, potential applications, and data requirements for each policy. I also categorized each policy into two broad groups (target-based and limit-based policies), a division which represents the modern ocean conservation management version of a debate with a century-long history in the environmental movement. This review provided important context for studying the interactions between scientific research, public concern and advocacy, and policy change for the case of shark conservation. Next, I surveyed 102 scientific experts (total response rate approximately 21%) who study sharks. Survey questions addressed their knowledge of and attitudes towards the shark conservation policymaking process. Respondents tended to consider themselves knowledgeable about and actively involved in both conservation-relevant research and direct environmental advocacy. Respondents tended to be broadly supportive of environmental advocacy from conservation no-profits, but raised concerns about the practices of a few perceived bad actors. Additionally, some surveyed scientific researchers reported that they have directly advocated for environmental policy change, bypassing the public concern and advocacy phase entirely. Majorities of respondents believed that sustainable fisheries exploitation of sharks is possible (84%), is happening in a few places today (83%), and should be the goal whenever possible instead of trying to ban fisheries (90%). This provides evidence that shark researchers have a preference for the target-based group of policies (which allow for sustainable fisheries management) over the limit-based family of policies (which focus on banning exploitation). This preference may be influenced by scientist’s area of professional training, or their experience working in nations with significant fisheries management resources. Notably, there has been a push for limit-based policies from some environmental groups in recent years, which shows that different stakeholder groups may support mutually exclusive policy solutions. These results revealed one stakeholder group’s perspectives on how scientific research interacts with advocacy and environmental policymaking. Next, I distributed a survey to 137 Florida charterboat captains who advertise fishing for sharks (25 responses, 18% response rate). I also performed a content and discourse analysis of each of their websites. Survey questions and website content analysis focused on their fishing practices and their knowledge of and attitudes towards shark conservation research priorities. My results showed that shark fishing is an important component of many charterboat businesses, and that captains value sharks for both economic and ecological reasons. Surveyed charterboat captains are also aware of and concerned by shark population declines. Eighty-two percent of surveyed captains reported that they always practice catch and release when fishing for sharks. Additionally, 100% of surveyed charterboat captains reported that their clients did not mind releasing their catch. This is likely because shark fishing is considered desirable for the challenge, not for the purpose of obtaining food. However, certain fishing practices in the charterboat recreational shark fishery, including possible targeting of physiologically vulnerable and legally protected hammerhead sharks, raise concerns and suggest the need for future policymaking. These results revealed that conclusions from scientific research (those concerning shark ecological importance and population declines) may have resulted in increased public concern among key stakeholders. As a consequence, non-extractive catch and release fishing may have become the norm in charterboat-based recreational shark angling. However, other conclusions from scientific research (those concerning the poor physiological suitability of hammerhead sharks for catch and release fishing) do not appear to have had the same influence on stakeholder concern or practices. Next, I provided an initial characterization of another stakeholder group. This study focused on land-based recreational shark anglers, a group of anglers with distinct fishing practices from charterboat-based anglers. To accomplish this, I performed a content and discourse analysis of a popular online discussion board used by land-based recreational shark anglers. This methodology is more limited than a survey, but can provide important insights into a poorly studied system. It can provide evidence that certain perceptions or practices exist within a studied sample, but cannot be used to determine how common those perceptions or practices are within the wider population. Results suggest that these land-based anglers are demographically distinct from other recreational anglers in Florida and nationwide. A much higher percentage of these anglers appear to be young, male, and low income. There was evidence of a perception that land-based anglers are being discriminated against by higher-income Floridians. Anglers were less likely to report bringing hammerhead sharks out of the water than other protected species, and were more likely to report releasing hammerhead sharks than some other protected species. However, there was no evidence of a significant change in reported fishing practices after a landing ban was implemented for hammerhead and tiger sharks. Several instances of illegal fishing practices were documented, and there was evidence that some anglers were aware that these practices were illegal. I found evidence that some land-based anglers were aware of and concerned by shark population declines, and evidence that some anglers typically released sharks they caught because of these concerns. There was evidence that some anglers were supportive of policymaking efforts to protect sharks from commercial fisheries, but there was also evidence of a perception that their own fishing practices play no role in shark population declines and shouldn’t be regulated. There was evidence of mixed attitudes and levels of trust towards scientific researchers and the environment. Results of this study provided further evidence that some scientific conclusions, such as those concerning the ecological importance of sharks and population declines in many species have reached key stakeholder groups. However, a stated belief that recreational angling has no impact on shark populations suggests that other important conclusions from scientific research, such as those demonstrating that recreational angling can have a significant impact on threatened fish populations, may not have reached these groups (or have been rejected by them). These results have important implications for understanding the interactions between scientific research, public concern and advocacy, and environmental policy change. Finally, to assess aspects of the foraging ecology of sharks, I performed δ13C and δ15N stable isotope analysis on 299 samples collected from 11 shark species between three distinct ecosystems. Analysis focused on assessing the relative isotopic niche breadth of these shark species, as well as patterns of isotopic niche overlap between these species. Relatively few prior studies have examined how trophic relationships between multiple co-occurring marine species change across their range. My results suggest the presence of intraspecific variation in patterns of relative isotopic niche breadth and overlap. The species with the largest relative isotopic niche breadth was inconsistent between locations. For example, bull sharks had the highest isotopic niche breadth of any co-occurring species in some locations, but intermediate isotopic niche breadth relative to other species at another study site. Additionally, there were inconsistent patterns of isotopic niche overlap between co-occurring shark species between study sites. For example, the SIBER ellipses of blacktip and blacknose sharks overlapped 85% in Biscayne Bay, but there was 0% overlap at Florida Bay. Only lemon sharks had significantly different mean carbon and nitrogen signatures be