Whale-watching (WW) is one of the fastest-growing tourism industries in a number of countries in recent decades, providing both economic and socioenvironmental benefits. WW has allowed the tourists who take part in it to gain increased knowledge of the biology and diversity of the species of whale seen and the environments in which they live (Filby et al., 2015; Pacheco et al., 2019). Local communities of artisanal fishers who participate in this economic activity benefit by diversifying from their traditional fishing activities, which allows them to increase their sources of income as fishing resources decrease (Parsons et al., 2003; Garrod and Wilson, 2004; Hoyt and Iñíguez, 2008; Guidino et al., 2020). One consequence of this is greater environmental consciousness, which stimulates interest in the conservation and protection of the marine fauna and their habitat (Higginbottom and Tribe, 2004; Zeppel and Muloin, 2008; Schuler and Pearson, 2019), both on the part of consumers (general public) and those who provide the services (e.g., fishers, researchers, businessmen) (Filby et al., 2015; Schuler and Pearson, 2019).

However, there is currently a strong concern over whether WW is an activity that really promotes the conservation of the subject species (Forestell, 2007). It has been widely reported in the literature that inadequate management of WW is an important source of perturbation for the animals, both in the short- and long-term (e.g., Corkeron, 2004; Bejder et al., 2006a; Argüelles et al., 2016; Sprogis et al., 2020b). Important sources of perturbation include a high number of boats in a confined area, very close proximity to the animals, the time and manner of approaching (and leaving) the animals, and lack of regulations or non-compliance with existing norms and regulations (Hoyt and Parsons, 2014). In the short-term, these sources may induce behavioral changes in the cetaceans, some of which may alter biologically important behavior such as feeding (Arcangeli and Crosti, 2009; Christiansen et al., 2013; Lesage et al., 2017) and resting (Avila et al., 2015; Sprogis et al., 2020a, b). Such behavioral variations may produce additional energy costs for the individuals (Williams et al., 2006; Christiansen et al., 2014), affecting their body condition in the medium and long-term, as well as the state of health and the reproductive success of the animals (Lusseau, 2005; Bejder et al., 2006b), which may eventually represent a threat to the conservation of the species exposed to WW (Corkeron, 2004; Lusseau and Bejder, 2007; Parsons, 2012). The other most frequent short-term effect reported is horizontal evasion, indicated by changes of direction in the movement patterns of the animals (Scheidat et al., 2004; Williams and Ashe, 2007; Williams et al., 2009; Schaffar et al., 2013; Schuler et al., 2019). Thus, in the presence of boats, movement patterns become less predictable as linearity decreases (the straight-line trajectory is lost) and reorientation increases (erratic trajectory) in order to evade the boats (Scheidat et al., 2004; Williams and Ashe, 2007; Schaffar et al., 2013). These evasion tactics vary depending on the number of boats and the approach distance (Williams et al., 2009; Schaffar et al., 2013). It has been shown that humpback whales (Megaptera novaeangliae) change their trajectory continuously when boats are close (Schaffar et al., 2013). It has been shown that the displacement trajectory of orcas (Orcinus orca) becomes more linear as the number of boats increases, indicating that the evasion tactic (increase in reorientation) may not be effective in the presence of a larger number of boats (Williams and Ashe, 2007; Williams et al., 2009). If evasive tactics are not effective, cetaceans must use strategies that are more energetically costly (Morete et al., 2007; Christiansen et al., 2014; Sprogis et al., 2020a, b), such as an increase in the velocity of displacement in the presence of boats (Christiansen et al., 2014; Schuler et al., 2019; Sprogis et al., 2020b). Another energetically expensive tactic used by cetaceans is vertical evasion, in which cetaceans increase their diving time (Stamation et al., 2010; Schaffar et al., 2013) and/or increase the rate of respiration (Christiansen et al., 2014; Schuler et al., 2019).

In Chile, tourism activities involving watching marine fauna and specifically WW are still incipient activities, growing by about 20% per year, with the potential for even greater development (Hoyt and Iñíguez, 2008). There are currently five localities in Chile where this activity is developed formally; Bahía de Mejillones in northern Chile, caleta Chañaral de Aceituno and Punta de Choros in north-central Chile, and caleta Puñihuil and the Francisco Coloane Marine Park in southern Chile (Hoyt and Iñíguez, 2008). Given the growth of the WW industry, the Undersecretary of Fisheries and Aquaculture (Subpesca) of the Chilean government published in 2011 the “General regulations for the observation of aquatic mammals, reptiles and birds and the recording of cetacean sighting” (D.S. No.38/2011; Subpesca, 2011). These regulations established the procedures and general requisites for the observation of these aquatic species, regulating among other aspects, observation distance, the method of approach of boats to the cetaceans and the behavior of tourists during the sightings (D.S. No.38/2011; Subpesca, 2011).

Caleta Chañaral de Aceituno is one of the favorite WW locations of tourists due to the high probability of sighting large cetaceans. This location is visited by a number of large cetacean species in the summer (e.g., blue, fin, humpback, and minke whales; Capella et al., 1999; Pérez et al., 2006; Toro et al., 2016; Sepúlveda et al., 2018). Fin whales are the most commonly observed species in the area (Pérez et al., 2006; Toro et al., 2016; Sepúlveda et al., 2018). The number of tourists visiting this location to participate in WW activities has increased exponentially in the last decade, from approximately 1,200 in the summer of 2010 to approximately 8,000 tourists in the summer of 2020 (Corporación Nacional Forestal, unpublished data). This location contains the Marine Protected Area “Isla Chañaral Marine Reserve” (D.S. No. 150-05; Subpesca, 2005), which has its own regulations for watching marine fauna.

Whale-watching is conducted by artisanal fishers of caleta Chañaral de Aceituno, which has provided an opportunity to expand and diversify their traditional activities (Sepúlveda et al., 2018). Due to the increase in the number of tourists and the importance of the species that visit the area, local authorities have introduced additional regulations in the marine reserve to those of the 2011 regulations, limiting the number of boats and the time they can stay with the animals (Res. Ex. No.655/2020; Sernapesca, 2020). However, in spite of these regulations, and considering the rapid increase of WW activity, to our knowledge, no study has addressed whether the cetaceans at this location are affected by WW and if so, to what degree. This study analyzed the behavioral responses of the fin whale to WW in this locality. The behavioral responses were evaluated using scenarios of WW “before”, “during”, and “after” the presence of WW boats. The number of boats and other factors such as year, month, group size, and distance from the observation point were also recorded. This study will provide an initial insight into the effects of WW on the fin whale in Chile, a species with known conservation issues.

The development and increase in WW has generated extensive discussion on the benefits and disturbance it produces. The economic and socio-environmental benefits have been widely recognized (e.g., Filby et al., 2015; Schuler and Pearson, 2019). However, there is growing evidence of the negative effects of tourism on the conservation of the species (Parsons, 2012; Higham et al., 2016). Considering the sustained increase in WW in the past few decades in a number of countries (Hoyt and Parsons, 2014; Schuler et al., 2019), monitoring of the effects of WW activity on subject species is fundamental to identify potential short-term perturbations with potential medium-and long-term consequences. Our study provides relevant information about the impact of WW on the behavior of the fin whale, a species poorly known in this topic, using a technique that does not interfere in the dynamics of tourism or in the behavioral response of the animals (Würsig et al., 1991; Morete et al., 2018; Piwetz et al., 2018).

Model results indicated that reorientation increased for both traveling and resting behaviors, while the directness index increased between the “before” and “during” WW scenarios. This means that in the presence of boats whales were making constant changes of direction and erratic movements, losing the movement linearity that they displayed before the boats arrived. These changes in the reorientation and directness index have been reported previously as responses of cetaceans to the presence of boats (e.g., Scheidat et al., 2004; Schaffar et al., 2013; Avila et al., 2015; Senigaglia et al., 2016; Sprogis et al., 2020a, b). Frid and Dill (2002) suggested that the alteration in the natural behavior of the animals in the presence of anthropogenic perturbation is produced because the animals perceive these perturbations similarly to a predation risk. For example, the minke whale (Balaenoptera acutorostrata) uses similar evasion tactics in response to the presence of tourist boats as in the presence of its natural predators orcas (Christiansen et al., 2013). This suggests that cetaceans could identify the presence of boats as a threat (Christiansen and Lusseau, 2014), resulting in the onset of avoidance behaviors.

Although the model with the most support for swimming speed had low explicative power, it identified a significant increase in the “after” WW scenario during traveling behavior; i.e., the swim speed of the whales increased after the boats had left the area. An increase in the reorientation and a decrease in the directness index in the “after” WW scenario were also observed. In contrast to these results, different studies have indicated that once the boat visits had finished, the whales returned to their initial behavior after a short time (e.g., Scheidat et al., 2004; Avila et al., 2015). The persistence, and even accentuation of the perturbation of behavior when the boats had left may be related to the behavior of the boat operators after the sighting had finished. Our field observations indicate that the boats would leave the area at high speeds, and sometimes passing in front of the animal. These two factors may be affecting the whales even more than the presence of the boats, since the animals accentuate the evasion strategy, increasing their speed and following less predictable trajectories, after the boats leave. The negative effect of high-speed boats has previously been described, showing that this factor limits the ability of the whales to avoid them (Parsons, 2012). Additionally, considering that the noise of the boats generated by the propeller cavitation produces adverse reactions in whale behavior (Erbe et al., 2019), and that more noise is produced at higher speed (Walker et al., 2019), the behavioral change of the animals may be due to the increase in the boats speed. Although we did not use the speed and path direction of the boats moving away as predictive variables, there is evidence that these variables negatively impact the behavior of large cetaceans (Heckel et al., 2001; Argüelles et al., 2016; Fiori et al., 2019), since this avoidance strategy increases the energetic cost for the animals (Williams et al., 2009; Christiansen et al., 2014; Sprogis et al., 2020b). We recommend that future studies incorporate other variables to describe the boat behavior, such as speed and direction of arriving and departing boats, to identify other potentially relevant factors in the responses of fin whales to WW.

The only model that included the number of boats as a significant variable was reorientation during resting behavior, indicating that the trajectories of the fin whales in this behavior became more direct (decreasing reorientation) as the number of boats increased. The behavior of maximizing linear movement as the number of boats increased was described previously in orcas, indicating that evasion responses (erratic and more sinuous movements) are employed when there are few boats, and by contrast, when the number of boats increases the animals choose a more linear trajectory to move away (Williams et al., 2002, 2009). Although the maximum simultaneous number of boats near a whale or group of whales was considerably smaller in this study compared to the report of Williams et al. (2009) (3 versus 14 boats), our results suggest the effect was similar to that reported for a high number of boats. This suggests that maintaining a low number of boats near an individual or group of whales is crucial to avoid drastic changes in the behavioral responses of the fin whale. This is especially relevant and reinforces the current measures in the Isla Chañaral Marine Reserve, which permit a maximum of two boats per whale or group of whales.

Our study shows that the behavioral responses of the fin whales are directly influenced by the WW activities. However, it must be noted that environmental and/or social factors could also contribute to these responses (Yazvenko et al., 2007; Gailey et al., 2016; Kavanagh et al., 2017), and may be related to the low explicative power (less than 10%) of some of the models. These include environmental factors such as wind speed, depth, time of day, distance to the coast (Yazvenko et al., 2007; Williams et al., 2009; Kavanagh et al., 2017); intraspecific factors such as age, sex and group size (Williams et al., 2009; Kavanagh et al., 2017); and others associated with tourist activity, such as distance and speed of approach and departure and path of approaching (Williams et al., 2009; Schaffar et al., 2013), among others. For instance, our study found that reorientation during traveling behavior decreased as the distance between the observation point and the animals observed increases. This result may not be related to WW, but rather explained by the increase in depth in the study area farther from the coast (Gaymer et al., 2008). More direct movement by the whales may facilitate less energetically costly travel in deeper areas (Gailey et al., 2016). This demonstrates that the behavioral responses of cetaceans are difficult to analyze, since they are influenced by many variables, which are often not linear (Williams et al., 2009). Due to this complexity, it is important to evaluate how environmental and/or social factors affect the behavioral responses of the whales (without anthropogenic factors), in order to identify if these responses could be attributed to natural factors or to anthropogenic disturbances (Kavanagh et al., 2017). Some of the environmental parameters for this specific study would be the depth, swell height, and wind speed that have been reported as relevant variables in other studies of whales (Gailey et al., 2016; Kavanagh et al., 2017).

Tourist development in caleta Chañaral de Aceituno is still at a low scale compared to other WW areas, both national and international, due to the small number of visitors (although this is increasing), and the use of small boats (Sepúlveda et al., 2016). In spite of this, we showed that even in this stage of development WW generates adverse effects on fin whales. Although this study only considered short-term behavioral changes, it is important to consider that behavioral changes in the whales may also result in long-term negative effects (Parsons, 2012; Schuler et al., 2019). Alterations in essential behaviors such as resting, feeding, continuous changes in direction and increased swimming speed to avoid boats produce an increase in energetic costs (Bain et al., 2014; Christiansen et al., 2014), which may cause deterioration in the physical condition of the animals if prolonged over time (Beale, 2007). This study area is important for the fin whale, since it is a recognized feeding zone on the Chilean coast (Pérez et al., 2006; Toro et al., 2016; Sepúlveda et al., 2018). Photo-identification has shown that some individuals stay in the area for weeks and even months, and some individuals return in different years (Toro et al., 2016), thus the perturbation by WW may not only be momentary, but rather some animals may be exposed to these perturbations frequently and over an extended period of time. Although we do not know the extent of the exposure of individuals to the WW activities (e.g., maximal daily exposure of the whales to the boats, proportion of the fin whale population that is being affected by WW), and the potential long-term effect of the observed changes in the behavior of fin whales, we do encourage the use of precautionary principle for minimizing impacts by adopting the codes of best practices from the beginning. Future studies should evaluate the level of exposure by relating information regarding permanence pattern and habitat use by fin whales, together with data from tourism activity (e.g., area covered by a boat during a tourist trip, number of boats).

The study area of caleta Chañaral de Aceituno has unique characteristics that make it an optimal location for WW. It is a recognized feeding area for the fin whale and other small and large species of cetaceans, several of which face conservation issues (Capella et al., 1999; Pérez et al., 2006; Toro et al., 2016; Sepúlveda et al., 2018). It is a marine protected area which can implement its own regulations, and tourism is at a small scale performed by artisanal fishers who have important knowledge of the local fishing resources and tourism, as well as identity and sense of belonging to the area (Sepúlveda et al., 2016). The results obtained in this study should be considered in the adjustment of the existing management tools and in the design of new complementary conservation strategies, to increase the balance toward the positive aspects of WW, as has been demonstrated in other places (e.g., Península Valdez; Chalcobsky et al., 2017). Artisan fishers are key actors to include in the design of cetacean’s conservation strategies. Given the importance of the conservation of the fin whale for their well-being, increasing the level of understanding is relevant to offer sustainable tourism services in the long term (Mace, 2014). Knowledge of whale behavior and responses to WW are critical to ensure the sustainability of tourism activity in this locality.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

Ethical review and approval was not required for the animal study because the study was carried out through land-based observations, so there was no manipulation or any intervention in natural behavior of whales.

MS-C and MS wrote the manuscript text, while all authors wrote, reviewed and edited the manuscript text. MS-C, GP, and MS contributed to the project design and funding acquisition. MS-C, FB, and LG contributed to the investigation methodology, field work, and data processing. MP-A contributed to the investigation methodology and ethology. CC contributed to the conservation approach. HA and CA contributed to the formal analysis. All authors listed have made a substantial, direct and intellectual contribution to the work.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.