3. How to Engage Tourists in Invasive Carp Removal: Application of a Discrete Choice Model

A lack of human and financial resources represents a bottleneck to invasive alien species (IAS) management all over the world, although it is widely recognized that IAS causes biodiversity loss (Didham et al. 2005; Sala et al. 2000). IAS have substantially damaged natural resource-based industries, such as agriculture, forestry, and fishery (Pejchar and Mooney 2009; Pimentel et al. 2005). For some governments and environmental managers, access to human and financial resources in long-term represents one of the biggest challenges for effective IAS management (Gardener et al. 2010; Simberloff et al. 2005).

IAS management programs have considered that public involvement is an essential tool to succeed, since it could overcome the management resources shortage, such as a lack of human and financial resources (Dunn et al. 2018; Gaertner et al. 2016; McNeely 2001). For example, common sun skinks (Eutropis multifasciata) were removed by tourists on Green Island, leading to a decrease in skink numbers (Chao and Lin 2017). Based on these results, the Convention on Biological Diversity (CBD) mentioned that citizens were one of the most important players in IAS management (CBD 2014).

In spite of a general agreement on the importance of public involvement toward the success of IAS management, such involvement is still difficult to achieve. Previous literature noted that public apathy toward IAS management represents one of the biggest barriers to public involvement. For example, people who underestimate IAS impacts in Japan tended not to support IAS management (Akiba et al. 2012; Mameno et al. 2017). Thus, public education and information provision could be effective in engaging more people (Bremner and Park 2007; Marzano et al. 2015). Based on these suggestions, some governments have provided relevant information; however, public awareness and public involvement remains insufficient (Dunn et al. 2018). Recently, the focus shifted to indirect approaches, which comprise neither education nor information provision. For example, Morgan and Ho (2018) showed that good tasting carp meat encouraged invasive carp removal.

So far, many previous studies have addressed the public attitude concerning an IAS and the management thereof (Bremner and Park 2007; Mameno et al. 2017; Wald et al. 2018), as well as the estimation of social values from IAS management programs (Nunes and Van Den Bergh 2004; Roberts et al. 2018). However, little research has focused on how to encourage people to participate in IAS management activities. Thus, our study—which uses a tour that comprises carp removal activities—can provide new insights into public engagements in IAS management. This work also extends the knowledge of voluntary conservation approaches. A few studies have focused on such approaches (Durán-Medraño et al. 2017); however, to our knowledge, no studies have addressed tourists’ attitudes concerning participation in conservation management.

The present study focuses on invasive common carp (Cyprinus carpio) management from the human dimension perspective. The invasive carp is one of the most invasive species, and is nominated as one of “100 of the world’s worst invasive alien species” (Kopf et al. 2017; Lowe et al. 2000), since the carp damages the native ecosystem by consuming organisms that are a food resource for native species (Gilligan and Rayner 2007; Morgan and Hicks 2013). Thus, recent conservation literature paid attention to its management (Marshall et al. 2018; Thresher et al. 2014; Uchii et al. 2014); however, social science research on this issue is limited—for example, Morgan and Ho (2018). Interestingly, the carp is a domestic alien species in Japan—it is a native species on the main island, but non-native on some of the small islands (e.g., Amami Oshima Island, which is our research site). Since few people would recognize carp as an IAS in Japan, the sharing of ecological information could play an important role, as suggested by previous literature. Historically, IAS management, including invasive carp, was greatly dependent on chemical and biological methods (Zastrow 2018). Thus, our research contributes to the existing body of knowledge on effective invasive carp management through application of human dimension approaches (Jacobson and Duff 1998; McNeely 2001).

Table 3.2 presents the estimated results of the RPL model. We applied the effect code to the dummy variables concerning Carp Removal option and Pick-up option. Thus, the relative values of coefficient are important instead of the absolute values. Table 3.2 shows the mean of coefficients, standard deviations of the random coefficients, and the effect of ecological information on each random parameter variables in the RPL models, with their standard errors. The standard deviations for each of the random coefficients indicate the heterogeneity of individual preferences relative to the preference of the population.

Table 3.2 indicates that the mean of the Carp Removal option coefficient is significantly negative (Coefficient = −0.366; SE = 0.131) at the 99.9% level: Carp Removal option decreased the probability of choosing canoe tours. However, standard deviations for Carp Removal option are also statistically significant: there is preference heterogeneity for Carp Removal option (Fig. 3.3). The mean of the respondents’ WTP for Carp Removal option was −988 JPY (100 JPY = about 0.9 USD and 0.8 EURO in November 2019). The other variables’ coefficients are also significant at over 95% levels, except for ASC. The coefficient of Pick-up option and Tour Time is positive, on the other hand, the coefficients of Tour Time ², Tour Fee are negative. While standard deviation of Tour Time coefficient is not significant, the other variables’ standard deviation of coefficients is also significant: there is preference heterogeneity.

Table 3.2 also shows the effect of ecological information provision, and they are not significant except for Carp Removal option. The coefficient of the effect of ecological information on Carp Removal option is significantly positive (Coefficient = 0.403; SE = 0.176), namely, information provision dramatically increased the probability of choosing canoe tours including carp removal (Fig. 3.3). The coefficient of Carp Removal option for respondents who were provided with information could be calculated through addition of the coefficient of Carp Removal option and the effect of ecological information on Carp Removal option, which had a positive result (Coefficient = 0.0368). Therefore, the utility of respondents had ecological information became positive if the option for carp removal was added to canoe tours, and the mean WTP for Carp Removal option by respondents who had ecological information was estimated at 99.3 JPY.

Public participation is an essential enhancement to IAS management, since it can compensate for the shortages of human and financial resources (Jenkins 1999; Lepczyk 2005; Trumbull et al. 2000); however, few studies have addressed the potential roles of tourists, although most of them visit wilderness areas such as national parks. We applied a discrete choice model to invasive carp management on Amami Oshima Island, Japan, to quantify tourists’ demand for participating in the carp removal program as a tour option. The results indicate that 64.2% of tourists who were not provided ecological information, about 100 tourists would avoid participating in carp removal activities as a tour option without any financial discounts when they have no ecological information (Table 3.2). In other words, on average, tourists with no information are indifferent to whether they participate in carp removal activities if they received a 988 JPY discount for a tour. This finding suggests that an additional IAS management option could decrease the number of tourists without any discounts, although preference heterogeneity should be discussed in more detail, which is described as follows. On the other hand, given the preference heterogeneity concerning the carp removal option by RPL models, 35.8% of tourists were willing to work for carp removal owing to their own motivations. Some tourists regarded carp removal as a tour activity, even when they were not provided with any ecological information (Fig. 3.3, Blue). This implies that a part of their preference heterogeneity could be derived from their original knowledge of and interests in nature and invasive management. This result also supports the view that tourist involvement could help to overcome the cost challenges of IAS management.

Although few studies have addressed IAS management as a tour activity, our finding is contrary to previous studies which have shown positive public support for IAS management. For example, Nishizawa et al. (2006) estimated the WTP for an eradication program of black bass (Micropterus salmoides and Micropterus dolomieu) as loading tax in Japan at about 2000 JPY. McIntosh et al. (2010) also showed that the WTP for invasive fish as a donation was about 50 USD. Mejía and Brandt (2015) showed that tourists had a positive WTP for a tour that enhanced IAS management. This contradiction indicates that the public, including tourists, has a motivation for financial support of IAS management; however, most of them are not willing to participate in IAS management, which suggests that human resources could become insufficient compared to financial resources in general.

How do we then engage the public in IAS management? The present study supports the views of previous literature by showing that the provision of ecological information affects tourists’ preference for carp removal activities in a tour (Bremner and Park 2007; Marzano et al. 2015). Tourists who received ecological information have a positive WTP (99.3 JPY) for participation in carp removal activities, which is 1087 JPY more than tourist who had no ecological information. In other words, provision of ecological information enables tour operators to receive a tour premium for including IAS management opportunities. This suggests that information provision leads to a win-win situation by enhancing IAS management while satisfying tourists’ demands and increasing tour operators’ profits. Recent tourism literature highlights that balancing conservation and the local economy through nature-based tourism is becoming increasingly important (Kubo et al. 2019). We demonstrated that this approach can even succeed in IAS management by sharing ecological knowledge with the public, as described in conservation literature (Akiba et al. 2012; Bremner and Park 2007; Dunn et al. 2018; Mameno et al. 2017; Marzano et al. 2015).

The other attributes concerning canoe tour design are also important for tourists’ decision-making and their involvement in carp removal activities. As shown in Table 3.2, tourists prefer to participate in tours of intermediate duration (i.e., about 120 min), and in tours that offer a pick-up option. These findings indicate that tourists are more encouraged to participate in a tour by adjusting the levels of the attributes of tour time and pick-up options, regardless of a carp removal option. Previous work by Morgan and Ho (2018) indicated that indirect approaches, which are not directly related with IAS management, are important. The present findings support their view of such indirect approaches, even in invasive carp removal management, and outline a new approach based on the use of nature-based tourism.

Our research site, Amami Oshima Island, is expected to be designated as a Natural World Heritage Site. Thus, IAS management has been paid more attention recently; however, a lack of resources has limited the implementation of IAS management. Our findings indicate that nature-based tourism which combined with the sharing of ecological knowledge with stakeholders, as well as indirect approaches, achieves sustainable IAS management.