The problems associated with anthropogenic food sources involving bottlenose dolphins are similar in many regards to those involving terrestrial mammals, but are in some ways less tractable. Food provided purposefully or inadvertently by humans brings dolphins into close proximity to people or human activities, and places the dolphins, and in some cases the humans, at risk. Direct provisioning alters the animals' behavior and places them at increased health risk from inappropriate food items, exposure to predators, vessels, fishing gear and vandals. Provisioning and inadvertent exposure to discarded catch or bait increases the likelihood of a variety of future human interactions, including approaches to boats, piers and fishing lines, and of depredation, the removal of catch or bait from lines, increasing the risk of entanglement in, or ingestion of, fishing gear (Wells et al., 2008; Powell & Wells, 2011). However, the high degree of mobility of the animals, their unavailability for observation most of the time because they are below the water's surface and the nature of the marine environment itself complicate investigation or characterization of the problem. Novel tools and approaches are needed for addressing this increasing problem at many sites around the world, and Donaldson et al. (2012) make an important contribution to the wildlife manager's toolbox.
The work reported by Donaldson et al. focused on Indo-Pacific bottlenose dolphins (Tursiops aduncus) along the south-west coast of Australia. However, similar problems exist through much of the worldwide, temperate to tropical marine range of the genus Tursiops, and the tools would have applicability across many sites. In the south-eastern USA, begging dolphins and dolphins entangled in fishing line are increasingly common. For example, near Sarasota, along the central west coast of Florida, the number of dolphins entangled or engaged in depredation or associated behaviors increased each year since 2004, and cumulatively, 14% of long-term Sarasota Bay resident dolphins were observed entangled or engaging in depredation or associated behaviors at least once during 2000–2007 (Powell & Wells, 2011). In 2006 alone, following a severe decline in available prey because of a harmful algal bloom, 2% of the resident dolphin community died from ingestion of recreational fishing gear (Powell & Wells, 2011).
Wildlife managers have access to a limited set of tools, and have limited resources for applying them. Directed application of available tools increases effectiveness. Research in Florida has demonstrated the relative importance of education/outreach and law enforcement for reducing human interactions with dolphins, with clear need and results shown for both approaches (Cunningham-Smith et al., 2006; McHugh et al., 2011; Powell & Wells, 2011). However, management resources are limited. In the USA, The National Marine Fisheries Service (NMFS), the federal agency responsible for protecting bottlenose dolphins under the Marine Mammal Protection Act (MMPA), currently has the equivalent of only about one management position dedicated to provisioning and other recreational gear interaction issues through its Southeast Regional Office, and while there are about 30 NMFS law enforcement officers, agents and supervisors in the south-east region, they must contend with the competing needs of enforcing all regulations from the Magnuson-Stevens Act, which governs marine fisheries management in the USA, the US Endangered Species Act and the MMPA. Management would clearly benefit from the ability to focus efforts on the most appropriate situations, and the approach of Donaldson et al. facilitates such a focus by using individual-specific data to identify important predictors of which animals are at greatest risk for interacting with humans.
The specific findings of Donaldson et al. regarding the importance of social learning are very interesting and highly relevant for their particular situation, but the strength of this predictor may vary across species and sites. Dolphin trainers have long been familiar with the concept of observational learning by dolphins, and they apply this knowledge by capturing and then shaping desired behaviors demonstrated by individuals after observing others (Norris & Dohl, 1980; Ramirez, 1999). Cultural transmission of natural feeding behaviors within a long-term, multigenerational resident dolphin community has been documented previously for bottlenose dolphins (Wells, 2003). Mothers have been observed engaging in human interactions related to anthropogenic food sources in the presence of their calves, which have subsequently engaged in similar behaviors, and both members of some strongly bonded, unrelated male pairs have engaged in such behaviors. However, using a somewhat different quantitative approach from that of Donaldson et al., Powell & Wells (2011) did not find a significant relationship between the likelihood of interacting with humans and coefficients of association with other interacting dolphins. Also, Powell & Wells (2011) found that sex and age appeared to be important predictors, with adult males being overrepresented in human interactions. These possible differences point to the utility of a standardized quantitative approach such as that of Donaldson et al. to be able to clearly identify and prioritize the specific factors of importance at different human interaction hotspots.
The Donaldson et al. study explored whether individual-specific data could be used to predict which individuals would learn to use anthropogenic food sources. Early studies of dolphin language and behavior led many scientists in other fields to dismiss dolphins as subjects of serious research, causing researchers to shy away from work that would investigate the individual characteristics and features that define them as distinctive individuals (Samuels & Tyack, 2000). The fact of the matter is that these animals do behave as individuals, and with their long life spans and social networks, they have the opportunity to impact many other individuals and leverage adverse change within populations. Donaldson et al. demonstrated that studies of individuals can have clear conservation benefits for populations. As more conservation attention is being focused on the cumulative effects of human activities on dolphins (Powell & Wells, 2011), it is crucial that robust measures of specific impacts be available for consideration, and Donaldson et al. have certainly advanced the field in this direction.