Marine ecotourism in the Gulf of California and the Baja California Peninsula: Research trends and information gaps

1 MarFishEco Fisheries Consultants, USA / UK. (AJ) (Corresponding author) E-mail: andrew@marfisheco.com. ORCID iD: https://orcid.org/0000-0003-3365-8768 (CG) E-mail: clairematiasgonzales@gmail.com. ORCID iD: https://orcid.org/0000-0002-0436-6531 (AT) E-mail: amanda@katuvi.com. ORCID iD: https://orcid.org/0000-0002-9892-8637 2 Blue Latitudes, La Jolla, CA, 92038, USA. 3 Katuvi, San Diego, CA, 92067, USA. 4 Nippon Foundation Nereus Program, Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, V6T 1Z4, Canada. (AMC-M) E-mail: a.cisneros@oceans.ubc.ca. ORCID iD: https://orcid.org/0000-0002-4132-5317


INTRODUCTION
Ecotourism can be defined as any recreational activity that explicitly involves the viewing and/or extraction of other living beings in the wild that incorporates some form of environmental education, has low environmental impacts, is intended to be sustainable and in some cases supports local conservation efforts. Ecotourism is one of the fastest growing industries globally (Das 2011, Das and Chatterjee 2015, Honey and Krantz 2007. Recreational enjoyment and associated economic and social benefits are therefore inherently and inextricably linked to nature conservation (Das and Chatterjee 2015, Gallagher and Hammerschlag 2011, Zeppel 2008. Marine ecotourism developed relatively recently compared with other forms of ecotourism that are historically tied to social traditions in Europe and North America, such as hunting, camping and freshwater fishing (Miller 1993). However, marine ecotourism activities such as whale and shark watching, snorkelling, scuba diving and recreational fishing attract over 120 million participants per year globally, generating more than 50 billion USD per annum and supporting over one million jobs (Cisneros-Montemayor and Sumaila 2010).
As ecotourism operations have expanded throughout the world, there have been several key lines of research into its establishment, performance and outcomes. Perhaps the most straighforward of these has been the valuation of economic benefits from ecotourism (e.g. Cisneros-Montemayor and Sumaila 2010, Spalding et al. 2017). This has developed into estimates of per-species or individual animal contributions that more directly connect ecotourism benefits with conservation strategies (e.g. Farr et al. 2014, Gallagher and Hammerschlag 2011, Vianna et al. 2012) and/or analyses of the distribution of benefits among local communities (Johnston 2000, Young 2016). With the growth in scale of local ecotourism industries, there are also efforts to consider negative impacts of ecotourism on marine species and ecosystems. This can include clear harm, for example by novice divers breaking coral reefs (Rouphael andHanafy 2007, Zakai andChadwick-Furman 2002) or tour vessel collisions with whales and whale sharks (Carrillo andFritter 2010, Neilson et al. 2012), but also more subtle, yet potentially significant impacts such as behavioural changes in response to ecotourism operations that may decrease individual fitness or risk aggressive encounters with humans (Hammerschlag et al. 2012, Neumann and Orams 2006, Ziegler et al. 2012. Another fundamental question that is being addressed is whether ecotourism ventures truly lead to improved environmental state. There are many examples of local improvements and increased awareness of conservation among ecotourists (Hausmann et al. 2017, Mieras et al. 2017), but long-term and large-scale outcomes remain unclear (Das 2011, Das andChatterjee 2015).
All of the ecotourism research themes and questions raised above are important for establishing truly successful ecotourism industries with a view to providing equitable and sustainable benefits in regional contexts. This is particularly important for ecotourism, given the evidence that ecotourism operations that operate without regard for the welfare of marine life or local residents can lead to outcomes including net negative impacts on ecosystems, poor relations with local communities, and negative perceptions of ecosystems and wild animals by tourists (Archer et al. 2012, Isaacs 2000, Higginbottom and Scott 2016. The first step in designing strategies for sustainable ecotourism establishment is therefore to identify existing conditions and challenges, including available information to inform new policies that are suitable for local environmental and socioeconomic conditions.
In México, over 16 billion USD per year are spent by 29 million tourists in general, sustaining over two million jobs across the country (Banxico 2016). There are highly successful ecotourism ventures in Mexico, including whale and shark watching, recreational fishing, diving and kayaking. The most important area for marine ecotourism is the Gulf of California region, including the states of Baja California, Baja California Sur, Sonora, Sinaloa, Nayarit and Jalisco. The extensive coastline of this area includes rocky reefs, mangroves, sea grass and kelp beds, a number of small and large islands, and large and productive upwelling zones. These diverse habitats support highly productive marine ecosystems, including iconic whale nurseries (Heckel et al. 2001, Salvadeo et al. 2013, aggregations of sharks and other fishes (Sievanen 2014), and exceptionally high marine and terrestrial species diversity (Arizpe and Covarrubias 2010, Grismer 2002, Howell et al. 2001. For example, shark watching revenue in the region (12 million USD) already represents more than half the landed value from shark fisheries in the country (21 million USD) (Cisneros-Montemayor et al. 2013). Consequently, the vibrant marine ecosystems in the Gulf of California and Pacific coast of the Baja California Peninsula produce a thriving ecotourism industry that has quickly expanded over the last few decades (López-Espinosa 2002). Sport fishing and diving are key year-round activities, though whale and whale shark watching have become essential seasonal components of ecotourism in the state (Cisneros-Montemayor and Sumaila 2010, Hoyt and Iñíguez 2008). As Mexico's coastal industries face increasing threats from warming ocean temperatures (Peterson et al. 2002, Vilchis et al. 2005, increasing unpredictable extreme weather events (UNFCCC 2007), market competition and declining fish stocks (Sievanen 2014), ecotourism has become a much-needed source of employment in the Gulf of California and in many coastal regions globally (López-Espinoza 2002, Rossing 2006. Suitable policies to ensure equitable and sustainable ecotourism operations must consider all available information about current performance, and operations in the Gulf of California are not without their challenges. Although fishers in the region often note a preference to continue fishing instead of switching to ecotourism operations, opinions related to such changes have been positive overall based on recent declines in fisheries revenues (Dagostino et al. 2009). Many authors, however, note that the economic changes that will come with moves towards ecotourism development must also come hand in hand with environmental sustainability if such growth is to be sustainable (Wall 1997). Inadequate development plans in the Los Cabos region already exemplify problems of rapid development, which without sufficient environmental management poses a significant threat to local ecosystems in the south of the Baja California Peninsula (Arizpe and Gámez 2011). Such problems include freshwater scarcity, groundwater contamination and habitat degradation. Uncontrolled development of tourism in Baja California presents a clear threat to ecosystems in the area, and future management must consider the environment in addition to industry development (Gámez and Ganster 2012).
Overcrowding in ecotourism operations is of additional concern as ecotourism operations become more important for revenue across the Baja California Peninsula. Overcrowding has been shown to negatively impact return rates of tourists (Ávila-Foucat et al. 2013) and the behaviour of sea lions (Labrada-Martagón 2005), and is suggested to negatively impact whale shark behaviour (Cárdenas-Torres 2007). If left unmanaged, such impacts will limit the longterm viability of what should be an environmentally sustainable industry. The key to the success of ecotourism operations will be the engagement of local communities. Acevedo (2012) note that local communities must be engaged in sustainable development and clearly define development goals which in many cases will be facilitated through collaboration with local NGO partners.
Although many ecotourism operations in Baja California indeed benefit local conservation (Aburto-Oropeza et al. 2011, Brenner et al. 2016, Mayer et al. 2018, they must be suitably managed to avoid environmental impacts (Cisneros-Montemayor 2012); a clear understanding of ecotourism research in the region will help collate past and direct future research efforts. We carried out a systematic literature review to characterize academic literature related to marine ecotourism, highlight key insights, and identify research strengths and gaps. This method was applied to ecotourism in the Baja California and the Gulf of California region of northwest Mexico. We discuss the findings of the review, consider the role of marine ecotourism operations in the future sustainability of the region and highlight areas in which we believe further study will benefit the conservation of the region.

Search criteria
We conducted a literature search for peer-reviewed publications, books and university theses, including factors related to marine ecotourism in Baja California and the states neighbouring the Gulf of California down to Puerto Vallarta, northwest Mexico. A factor 'related' to marine ecotourism is any measure which the authors of an article specifically link to the ecotourism industry, such as employment, economic met-rics, tourism infrastructure, environmental status and variations thereof. We therefore define an 'article' as a published paper and a 'study' as an investigation of marine ecotourism or factors or variables related to marine ecotourism within a published paper. An article may therefore have more than one study within it if it addresses multiple ecotourism-related variables.
The literature search was undertaken using the commercial search engine Google Scholar, which indexes the full text of scholarly literature across an array of publishing formats. Combinations of the following general search terms were used: 'marine', 'ecotourism', 'tourism', 'industry', 'holiday', 'vacation', 'recreation', 'economy', 'infrastructure', 'employment', 'environment', 'eco', 'nature', along with a secondary search using terms related specifically to marine ecotourism activities in Mexico, including 'diving', 'snorkelling', 'whale watching', 'shark watching', 'beach', 'kayak', 'sailing', 'cruise', 'fishing', 'angling', 'wildlife', 'national park' and 'protected area'. For a list of search combinations used and resultant internet 'hits' and numbers of peer-review journals for each, see Supplementary material Table S1. Google Scholar was chosen over Web of Science and Scopus as it gives a higher number of results per general search term (on average), covers non-ISI listed journals (a wider search base) and gives lower citation noise [lower citation variation (85% unique entries compared with ISI's 60%)], which means that there are fewer replicated citations per search (Pauly andStergiou 2005, Meho andYang 2007).
The first one hundred search results from each keyword combination were examined, so a total of 2300 hits were evaluated for inclusion in the review (23 searches × 100 hits of each). From each article highlighted in the literature search, eight data variables were extracted and entered into a database (see Table  1 for details). In addition to categorical variables, brief one-sentence summaries of each article were made to allow discussion of more general, non-quantifiable patterns post-analysis and to increase the utility of the database resulting from the literature review.

Statistical analyses and graphical outputs
We used ordinary least squares regression to investigate trends in the number of publications over time as well as the methods used within each and how the research focus has changed. It must be noted that the statistics described herein for each are casual tendencies as in all cases normality is violated but the data were not transformed in order to reduce the tendency to inflate type I error. The geographic distribution of the studies, years of publication, the subject organisms of the studies (if applicable) and the topic of focus (ecology vs economy vs social wellbeing) across Baja California was visualized using the Tableau 9.1 software. Finally, in order to elucidate the financial investments being made in marine ecotourism research in Baja California, we noted the agency types from which funding came for each publication reviewed (where specified).

RESULTS
The literature search identified 47 publications that directly (quantitative analysis) or indirectly (discussion) addressed marine ecotourism in the Gulf of California and Baja California Peninsula, Mexico (see Supplementary Table S2). There was a significant increase over time in the number of all publications (n=47), peerreviewed articles (n=25) and books (n=7) from 1994 to 2014 (R 2 =0.43, P <0.01; R 2 =0.25, P=0.02; R 2 =0.25, P=0.02, respectively) (Fig. 1). The number of theses (n=15) studying marine ecotourism in Baja California also increased over time, although the increase was not statistically significant (R 2 =0.17, P=0.065). The majority of studies were concentrated around Baja California Sur, with only four representing the eastern coast of the Gulf of California (Supplementary material Table S2).
There was also a significant tendency for the number of studies using survey interview techniques (n=26) to increase over the 20-year study period ( Fig.  2; R 2 =0.31, P=0.039). Similar linear increases were seen for literature review techniques (n=12) and studies compiling observed data for quantitative analysis (n=22), although the increases were not statistically significant (R 2 =0.31, P=0.087, R 2 =0.16 P=0.075 respectively). There were no tendencies noted for study methods using qualitative discussions (n=7), modelling approaches (n=7) or GIS-specific studies (n=4).
Of the publications reviewed, 70% focused on a species or species group, including formal quantitative analyses (Figs 3 and 4A). Cetaceans (Eschrichtius robustus and Megaptera novaeangliae) and fishes (Istiophoridae spp., Rhyncodon typus and Makaira nigricans) were the most common groups studied, while turtles and pinnipeds were the least studied. Although one species of bird (Charadius alexandrinus) was noted, this was from a study undertaken in 1976 (Anderson et al. 1976) that only mentions development potential in Baja California and therefore does not compare well with the more rigorous discussions of marine tourism in Baja California over the last 20 years. The majority (68%) of publications focused    on ecological goals or discussions, 25% focused on economics, and the remaining 7% focused on human social wellbeing (Fig. 4B). Funding for marine ecotourism studies of the Gulf of California came primarily (23%) from Mexico-only sources, and equal proportions (15% each) came from Mexican sources with foreign collaborators and from only foreign sources. Almost half (48%) of the publications did not describe the source of the financial support for the project, study or article, so drawing firm conclusions regarding funding patterns is difficult in this instance.

DISCUSSION
Ecotourism is a rapidly expanding industry throughout the world, and certainly in the Gulf of California and Baja California Peninsula region of northwest Mexico. Our review summarizes key research insights, trends, and gaps and highlights in particular information that is unevenly available for specific regions, themes and species. We discuss each of these trends and their implications below, address potential limitations of this study, and offer considerations for future ecotourism research and policies in the region and elsewhere.

Trends over time
Increased research effort over the 20 years reviewed is a promising trend, which, considering the potential of the Baja California Peninsula for ecotourism operations, the authors hope will continue. In particular, we believe that a continued effort to increase the amount of peer-reviewed output in the field will benefit the development of the marine ecotourism industry in a sustainable way, as it already has done, for example, in the formation of strict rules governing sighting programmes for whales (Heckel et al. 2003) and whale sharks (Cárdenas-Torres et al. 2007). Although theses made up approximately one third of all published materials reviewed, very few showed a similar publication rate for peer-reviewed articles. This could indicate a wasted research effort if, for example, NGOs or government agencies rely only on robust, peer-reviewed scientific output rather than student theses, whose rigour can be questioned more easily.
In terms of the study methodologies within the peerreviewed publications, the increasing number of quantitative studies is also promising. Quantitative surveys likely give more strength to conclusions drawn from them than qualitative-only studies. They are also likely to be more directly usable in management applications, which often rely on numeric thresholds, such as carrying capacities of an area or the potential revenue of a given activity. The low numbers of studies employing modelling and GIS techniques is understandable as these are much newer analytical techniques than the other methods reviewed.

Locations of focus in Baja California
It is interesting to note that few studies on the Sonoran and Sinaloan coast were uncovered by our literature search. This paucity could be caused by a lack of research investment in these areas, a low number of marine ecotourism operations along these stretches of coast, or the fact that our literature search did not select these areas well using "Baja California" as a geographic search term. The south of the Baja Peninsula was comparatively well studied, with the majority of recent studies occurring in Cabo Pulmo and La Paz. This is likely due to the age of marine ecotourism operations in these areas based on the infrastructure (airports, road networks etc.) that has allowed rapid local growth. The spread of study type (ecology, economy and social wellbeing) across Baja California showed no distinct pattern, although it is clear that ecological publications dominate across the peninsula. Much of coastal Baja California and its surrounding waters are understudied, which is evident from the large stretches of coast for which no publications were found and the grouping of publications mainly around established towns and cities. This finding highlights a tendency for studies of marine ecotourism to be reports on extant operations rather than projections or predictions on the future potential of areas yet to be developed. This is something that would be beneficial to address, particularly in areas of ecological importance. In instances in which data already exist, development will be able to account for more than just potential revenue gains if information is freely available to stakeholders from the outset of a development proposal (e.g. Vanderplank et al. 2014).

Species of interest
The large number of publications studying or discussing whale sightseeing tourism were focused on the Pacific coast of the Baja California Peninsula, including the well-established ecotourism destination Laguna San Ignacio (Chong 2008, Rossing 2006. Being the most charismatic of the species noted, it is not surprising that whales (Gray and Humpback) were the largest of the organismal groups noted. The large number of studies concentrating on reef fish species are centred around the rocky reefs of the Cabo Pulmo National Park, as were the studies noting invertebrate species (Arizpe 2004). A 20-year closure to fishing has led to a 463% increase in fish biomass (Aburto-Oropeza et al. 2011) at Cabo Pulmo, which is now an important model system of successful ecotourism and marine conservation globally (Leslie et al. 2013). Surprisingly, only one of the studies highlighted in the literature search looked specifically at sports fishing in Baja California. Considering the general declining state of the Gulf of California's fishing industry (Sala et al. 2004, Lluch-Cota et al. 2007) and the large number of sports fishing operators working from Baja California (Sievanen 2014), we expected more publications to detail the sports fishing industry as an economically viable alternative to traditional fishing (Barnett et al. 2015).

Ecology, economy, social wellbeing
As mentioned above, we decided a priori that each study could be categorized into either ecological, economic or social wellbeing studies, or any combination of the three. Overall, a tendency towards ecology over economy over social wellbeing was clear. This pattern was also clear within papers that discussed a combination of two or all three of the study topic types, discussions of ecology taking precedence over economy and few analyses or conclusions regarding human social wellbeing. The lack of social wellbeing may, however, be a result of the relatively new industry of marine ecotourism in Baja California, which in some cases may mean that little social change has yet taken place since new operations were set up in certain areas. This, however, does not appear to be true for the more developed areas such as Cabo Pulmo, Cabo San Lucas and Ensenada, the locations of all of the social studies reviewed. The prevalence of ecological publications related to marine ecotourism in Baja California may well be attributed to the research objectives of the main funding bodies, all of which are ecology-based rather than economic or social science institutes / agencies [CONACYT (Consejo Nacional De Ciencia Y Tecnología), CICIMAR (Centro Interdisciplinario de Ciencias Marinas) and CICESE (Centro de Investigación Científica y Educación Superior de Ensenada)]. Mexican agencies have been the most prevalent funders of the publications highlighted in our review, most notably CONACYT.

Limitations and considerations
Our comprehensive literature search allowed us to highlight some important trends and patterns in the field of marine ecotourism research in the Gulf of California and Baja California Peninsula, Mexico. It is, however, important to discuss possible limitations of our approach and the bearing they may have on our conclusions. This quantitative, systematic analysis included theses, books and conference papers. Although these three publication types do undergo some sort of peer-review process, it could be argued that it is not as stringent as that of peer-reviewed journal articles, which might invalidate some of the findings within the publications presented. Our analyses, however, are concerned with patterns in a field of research rather than scientific rigour.
Although the time period of publications we reviewed does not include anything earlier than 1994, this time period suitably captures regional research patterns; indeed, the literature search only highlighted one paper outside of this time frame (Anderson et al. 1976). Work by López-Espinosa (2002) also indicates that ecotourism in the southern Baja California Peninsula began following this period. Although we used a comprehensive, quantitative approach to select relevant publications, it is impossible to say that the literature search is exhaustive. There are likely to be articles that were missed by the search term combinations we chose or have never made it into mainstream search-engine territory. Finally, it must be noted what truly classifies "marine" in our review. One fifth of all of the publications included in the review actually discuss what may be classified as terrestrial ecotourism instead of marine-based activities. Such publications were, however, kept in the analysis if they linked strongly with marine systems (e.g. coastal wetlands or sea cliffs) or the main discussion in the publication also drew conclusions relating directly to marine systems (e.g. effluent from hotels running into marine systems).
It is also important to mention the robustness of our analysis of trends using ordinary least squares regressions. Although the method is appropriate for the analysis of linear trends, a lack of data in some instances means that our interpretations must be taken with caution. For example, the statistical significance of regressions that were run with few (e.g. less than 10) points is based on a small sample size and may therefore not be wholly representative of the existence or absence of real-world trends. Unfortunately, because of the lack of data for some of the regressions run, this problem cannot be overcome. The lack of data does, however, highlight the fact that, for example, there have been few GIS studies of ecotourism in Baja California for the time period analysed. Overall, however, we believe that our literature review methodology captures the field of research publications relating to marine ecotourism in Baja California well, and provides important information relating to patterns in the field and future areas for development.

Future perspectives
Our review highlights some interesting patterns in the research effort relating to marine ecotourism in Baja California and the Gulf of California. However, there are multiple research areas in this field that could be bolstered to provide a more complete analysis of this industry. For example, theses form an important part of the total literature yet few have been published in peer-reviewed journals. Promoting the publication of theses in peer-reviewed publications may give their findings more weight in potential management decisions and a wider audience in general. In addition, there are few current modelling and GIS-specific studies of marine ecotourism in Baja California. Investing more research effort in predictive modelling studies and GIS outputs for use by resource managers (predicted, future quantities and map layers) will likely yield beneficial results.
A common theme in publication conclusions is the need for collaboration and involvement from all stakeholder groups. Collaborations between stakeholders and the research community will be strengthened if research actively incorporates stakeholders into research and reports findings back to those groups affected by the industries under study. For instance, sport fishing is under-represented in the literature as an ecotourism activity, yet makes up an important part of Baja California's ecotourism (Cisneros-Montemayor et al. 2012). More research outputs relating to the commercial and recreational fishing sector from the ecological, economic and social wellbeing perspectives would inform both the tourists taking part in such activities and the commercial fishers in these regions, who may consider converting to sports fishing operations if commercial catches in the Gulf continue to show signs of overexploitation (Sala et al. 2004).
Finally, there are many coastal areas in Baja California and the Gulf of California that appear never to have been studied. As tourism and human populations throughout the region continue to grow (Agersted 2006, Center for Responsible Travel 2017), it is important to have information, data and opinions ready for development committees wishing to transform areas of Baja California into holiday hotspots. Pre-development studies will be hugely beneficial in informing stakeholders but must be directed at areas of promise that are likely to be subject to development in the coming years. While overall ecology dominates the literature over economy and social studies, future studies that incorporate the fields of economy and human social wellbeing would provide managers with a more complete suite of information relating to Baja California's marine ecotourism development.