Determining the factors contributing to human-dolphin interactions in a long-term resident inshore bottlenose dolphin community

End Date: 05/30/15


The overall goals of the proposed project are to conduct a pilot study to determine the contributing factors associated with human-dolphin interactions causing unnatural foraging behaviors in Sarasota Bay, FL, develop standardized methodologies and identify minimum data requirements needed to accurately characterize HI, and provide information to managers to improve management and mitigation efforts related to HI.  Specific objectives are:

1)  To estimate the population size and proportion of individuals engaged in HI.

2)  To characterize potential anthropogenic sources of food.

3)  To relate availability of natural prey to use of anthropogenic sources of food.

4)  To characterize HI through focal animal follows and social structure analyses.

5)  To sub-sample data to determine minimum effort required to meet objectives.

6)  To build on previous outreach experiments to develop improved approaches.

7)  To obtain updated information on HI for use in outreach efforts funded independent of the proposed project.


The proposed research will integrate several well-tested, standardized field activities with new analytical approaches to meet stated objectives. For example, we will use standard photographic identification surveys and mark-recapture techniques to estimate population size and determine the proportion of individuals engaged in HI in Sarasota Bay. During these same surveys, we will also document instances of HI and collect new data on potential anthropogenic sources of food throughout the study area, including commercial and recreational fishing activity, recreational boaters, and tourism businesses. While this survey data will provide much of the basic information needed to characterize HI, we will build upon basic questions using new analytical methods including state-space or other predictive models and social network analyses to explore spatial and temporal heterogeneity in HI and social factors contributing to persistence and spread of unnatural foraging behaviors within the Sarasota Bay community. In addition, we will monitor natural prey stocks seasonally using purse-seine techniques, which will provide an environmental context through which we can better understand the likelihood of resident animals using anthropogenic food sources.  Finally, we will use both previous and novel behavioral focal follows for individuals known to engage in unnatural foraging behaviors to characterize details of HI at this site.  


Increasing adverse human-dolphin interactions (HI) throughout the Southeast United States (SEUS) are a major management and conservation concern because of their potential to injure or kill dolphins and contribute to unnatural foraging behaviors such as begging, depredation, and scavenging. Many of these interactions, including provisioning and harassment by humans, are prohibited as “take” under the Marine Mammal Protection Act (MMPA). However, managing and mitigating HI in the SEUS is difficult due to the complex nature of the interactions in different geographic areas coupled with a poor understanding of the magnitude of the problem, suite of factors contributing to HI (and their spatial and temporal components), or details and behavioral consequences of HI for the animals involved in these interactions at different locations. While researchers have studied HI at several sites in the SEUS, efforts to understand the problem on a regional scale have been hampered by the piecemeal nature of these projects and the lack of standardized approach to characterizing HI across sites. We propose to use the long-term “natural laboratory” of Sarasota Bay, Florida, to conduct a pilot research project on HI, taking advantage of the multi-generational resident inshore bottlenose dolphin community.  This project will determine the primary factors contributing to HI causing unnatural bottlenose dolphin foraging behaviors in Sarasota Bay, and will also establish standardized, transferrable methodologies and help identify minimum data requirements to accurately characterize the nature of these interactions in resident inshore dolphin populations in other parts of the SEUS. 

This work will be performed by the Sarasota Dolphin Research Program (SDRP) as part of the world’s longest-running study of a dolphin population. The SDRP has conducted observational and capture-release efforts for more than four decades on a community of about 160 dolphins in Sarasota Bay.  Through these efforts, the SDRP has compiled records on individual ranging and social patterns, health and body condition, life-history parameters, behavior including human interactions, mortality patterns and reproductive success. This resident community spans five concurrent generations, and many individuals display strong site fidelity to the area over periods of decades. This high degree of site fidelity means that individuals can be predictably resighted, local threats to the resident community can be characterized and evaluated, changes over time can be detected and monitored, and behavioral observations can reliably be focused on specific individuals or classes of animals.

The wealth of long-term background data in Sarasota Bay allows us to characterize the factors contributing to HI at this site in unique detail, including spatial and temporal differences in prey availability, robust estimates of population size and the proportion of individuals engaging in unnatural foraging behaviors over time, and in-depth HI histories and focal observations on individual dolphins.  Approximately 25% of resident dolphins have been documented engaging in unnatural foraging behaviors or human-dolphin interactions of concern, including begging, provisioning, depredation, scavenging, and patrolling, and we have conducted several previous studies aimed at addressing these issues (e.g., Cunningham-Smith et al. 2006; Powell and Wells 2011; Wells et al. 1998, 2008).  Thus, we feel that we can effectively build on our long-term program to meet the overall research goal in a timely and comprehensive manner. In addition, we can provide a unique perspective garnered from a large, long-term, in-depth dataset which allows for sub-sampling to determine the minimum effort/data required to accurately characterize HI and meet research objectives.  Identification of such minimum effort requirements will be beneficial to NOAA in planning comparison projects in other geographic areas with limited background data and available resources, but where similar conservation concerns related to human-dolphin interactions exist.