Tour Boats Research Articles

Southern Hemisphere humpback whales (Megaptera novaeangliae) (Artiodactyla: Balaenopteridae) singing activity at Caño Island Biological Reserve, Costa Rica before, during, and after COVID-19 lockdowns

Introduction: Boat traffic is recognized as a major contributor of underwater noise. Increasing presence of boats in coastal habitats is predicted to have important repercussions on the communication of marine mammals. In Costa Rica, the waters of the Caño Island Biological Reserve are an important breeding area for humpback whales from the Breeding-Stock G (BSG). Their predicted and abundant presence has fueled the development of whale watching activities as an important component of the local economy, and while the country has norms of conduct for this activity, whales often interact with multiple boats at the same time. The lockdowns associated with the COVID-19 pandemic provided a unique opportunity to study the potential impacts of noise associated with boat traffic on the singing activity of humpback whales.
 Objective: Determine whether noise levels and boat acoustic presence around Caño Island Biological Reserve changed during the COVID-19 lockdowns, and if it did, what is the impact on song detection of BSG humpback whales.
 Methods: Acoustic recordings were made using a bottom-mounted autonomous underwater recorder for 30 days in September 2019, 2020, and 2021, resulting in a total recording effort of 480 hours.
 Results: Our results show that broadband underwater noise levels (dBRMS) during pre-lockdown were significantly higher, particularly at frequencies below 1kHz, than during and post-lockdown. This is likely due to a decrease in the proportion of boat acoustic presence during the lockdown. Although the proportion of whale songs detected did not vary among years, whale songs were detected similarly throughout the day during the lockdown, compared to pre-and-post lockdown where the proportion of whale song presence decreased during hours when more boats were present.
 Conclusions: This study shows a clear change in underwater noise levels during the COVID-19 lockdown, likely due to a decrease in boat presence. The study also highlights the potential impact of noise associated with boat traffic on humpback whale singing activity. The results of this study can inform the Conservation Areas of Osa (ACOSA) in charge of managing Caño Island Biological Reserve, to develop and implement mitigation measures to regulate underwater anthropogenic noise associated with tour boats.

Analysis of the Implementation of Hotel Tax Collection on Tour Boats in West Manggarai Regency, East Nusa Tenggara Province Year 2019-2022

Tourist who travel to tourist destinations using tourist vessels and utilize accommodation services on board generate transactions that generate revenue. However, the collection of hotel tax on tourist vessels in West Manggarai Regency has not met the target set by the local government. This phenomenon indicates a low level of taxpayer compliance. Therefore, it is essential to implement the Regent Regulation of West Manggarai Regency No. 58 of 2017 regarding the Procedures for Hotel Tax Collection on Tourist Vessels. The objective of this research is to analyze the implementation of the Regent Regulation on the Procedures for Hotel Tax Collection on Tourist Vessels and identify the obstacles faced and efforts made by the Regional Financial Management Agency to overcome these challenges. The research methodology employed in this study is qualitative with a descriptive type. The findings reveal that the implementation process of the Regent Regulation on the Procedures for Hotel Tax Collection on Tourist Vessels has not been executed effectively and doues not comply with the applicable rules due to a lack of education and information dissemination, inadequate human resources capabilities, low implementor supervision, insufficient personnel, and suboptimal inter-organizational communication. Therefore, there is a need to enhance activities related to socialization, education, supervision, and human resources training.

Tax Collection Authority for Hotels Aboard Tourist Boats After Law Number 1 of 2022 and Law Number 7 of 2021

ABSTRACT
 This research was conducted with the aim to find out how the regulations related to the authority to collect taxes on hotels on board tours after the issuance of the HKPD Law and HPP Law. Taxes on hotels aboard tour boats so far have created a separate polemic regarding the authority of the tax collection agency authorized to collect this type of tax, namely, whether it is a Regional Tax which is the authority of the Regional Government or is it the Center which is the authority of the Central Government, this is because there is an object that is the same wedge between the hotel tax on the tour boat and the VAT on the tour ship itself. Where in Law Number 28 of 2009 it has not been specifically regulated regarding whether staying on a tour boat is part of the hotel tax. For hotels on board tours it is more appropriate to be collected by the Regional Government. In the preparation of laws related to local taxes in the future, to include hotel tax coverage from a more substantive point of view and includes the nature of the accommodation services business itself, which in the future will likely be very transformative, not only on ships, but also by train, car and other modes, for this reason, it is better not to be limited by a limited scope.

Humpback whales in Banderas Bay, Mexico: relative abundance and temporal patterns between 2004 and 2017

Banderas Bay, Mexico is an important breeding and transit area for the North Pacific humpback whale (Megaptera novaeangliae) population. In this paper we estimated relative abundance (RA = number of whales/hours of navigation) as a proxy to assess population temporary patterns in the area. We analyzed data from 14 breeding seasons (2004-2017), collected between December and March each winter. A total of 8,013 whales were observed in 1,394.6 navigation hours. Average seasonal RA was 5.7 whales per hour with a maximum of 7.5 (2013) and a minimum of 4.0 (2016). Sea surface temperature (SST) averaged 25.1°C and remained within the range considered optimal for humpback whale reproduction areas. SST showed no significant correlation with RA (r = 0.183). Inter-seasonal RA values suggested an increase throughout the study period, although the increase was not statistically significant (R = 0.32; R2 = 0.10; t = 1.15, p > 0.05). Intra-seasonal analyses showed that RA in December and January were significantly higher (U = 150, p < 0.05) than in February and March; this pattern was consistent throughout the seasons of study. These results represent a shift in the intra-seasonal abundance peak relative to previous studies when most whales were observed between January and February. It is important to recognize changes in population parameters of humpback whales in breeding areas to improve management practices. This study also highlights the potential of opportunistic platforms, such as whale watching tour boats, as viable sources of quality information, particularly in contexts when funding is limited.

Tourist Boat Electrification

As a city crossed by rivers, Surabaya has the potential for attractive water tourism. Kalimas is one of them. Kalimas is a river that divides Surabaya. Kali Mas is a tributary of the Brantas River. This main river flows from Mojokerto as its headwaters, then flows to the northeast, empties into Surabaya, and ends in the Madura Strait. Muara Kali Mas has been Surabaya's traditional port for centuries. This port became the gateway to the capital of the Majapahit Kingdom (in Trowulan), and became part of the Surabaya people's battle against the allies before November 10, 1945. In various countries, river tourism has developed. Not only for city residents, but has become part of the State's tourism. One example is in Italy, namely tracing the river canals in Venice in Italy. Everything is described so well that everyone who comes wants to try it. Experiences and interesting photo documentation make river tourism an opportunity to develop. River tourism can be a potential alternative for Surabaya residents. Become a means of recreation or further developed into a tourist vehicle of national and even international standards. An important means of water tourism is a boat. Tour boats were developed to support the success of this tour. This article discusses the electrical installation for tourist boats that will be used on the Kali Mas River. Its power source is taken from diesel engines and also from solar panels that are capable of generating electricity.

BOAT-GENERATED WAVES AND EROSION ON THE SHORE OF THE XINGÓ POWER PLANT RESERVOIR

In fluvial environments, water speed depends on important factors such as longitudinal slope, water volume, channel shape (cross section), bed roughness, and water viscosity, all of which affect speed in different sections of the channel in which it flows. Waves generated by boats present a complex distribution, with the formation of primary and secondary wave systems. The objective of this work was to describe the erosive effects of waves from tourism boats on the lake banks at the Xingó hydroelectric power plant in northeastern Brazil. Measurements taken on site as well as data from environmental monitoring systems were used to determine the characteristics of the lake, while wave heights were calculated according to the effects of transverse and divergent waves. The wave propagation behavior observed in this present study alone cannot be responsible for erosion on the banks and slopes of the lake, since this is also associated with the presence of wind fetch, human activities, deposit of transported sediments resulting from operations at the power plant, as well as other factors. The findings confirmed observations that the tour boats do not directly cause erosion, since they are limited to subcritical speeds, but wind was seen to be directly related to this phenomenon

An Ecoacoustic Snapshot of a Subarctic Coastal Wilderness: Aialik Bay, Alaska 2019

I recorded the ambient sounds at three locations in the wilderness of Aialik Bay in Kenai Fjords National Park, Alaska between 25 June and 21 September 2019. My aim was to capture an ecoacoustic snapshot of the coastal soundscape to provide a comparable baseline for evaluating wilderness characteristics defined by the Wilderness Act of 1964. I visually and empirically characterized the Aialik Bay wilderness soundscape using the acoustic metrics of soundscape power (normalized watts/kHz) and Normalized Difference Soundscape Index (NDSI) from 5373 five-minute recordings, combined with visual and aural spectral examination of 4386 recordings. Soundscape power exhibited similar patterns across frequency intervals with sound sources primarily occurring in the low-frequency (1–2 kHz) and mid-frequency (2–5 kHz) intervals. Significant differences within frequency intervals between sites suggested the presence of distinct sonotopes. Low-frequency sounds were dominant across all three sites with peak soundscape power values across study days and 24 h timeframes attributed to wind and occasional periods of technophony emitted from commercial tour boats and private boating activities. Low-frequency geophony from wave action was ever present. Technophony exhibited some predictable patterns consistent with the timing of sightseeing boat tours. Peak values of soundscape power at mid-frequencies were attributed to the geophony of rain. Although biophonies were less common than geophonies, the choruses of songbirds were prevalent in July and promptly occurred daily between 0300 and 0600. Biophonies generally declined over the course of the day. All sites displayed negative NDSI values over most study days and consistently negative values over 24 h time frames, indicating a soundscape primarily influenced by low-frequency geophony and periods of technophony. However, NDSI values showed patterns and peaks similar to biophonies at mid-frequency intervals indicating biophony was still a notable contribution to this geophony-dominant soundscape. Despite the acoustic footprint of motorboat noise detected at all sample sites, the soundscape of the Aialik Bay wilderness was dominated by the natural sounds of geophony, biophony, and occasional periods of natural quiet indicative of a wilderness only partially impacted by technophony.

Tour boats affect the activity patterns of bottlenose dolphins (Tursiops truncatus) in Bocas del Toro, Panama.

Bottlenose dolphins (Tursiops truncatus) of the Bocas del Toro archipelago are targeted by the largest boat-based cetacean watching operation in Panama. Tourism is concentrated in Dolphin Bay, home to a population of resident dolphins. Previous studies have shown that tour boats elicit short-term changes in dolphin behavior and communication; however, the relationship of these responses to the local population’s biology and ecology is unclear. Studying the effects of tour boats on dolphin activity patterns and behavior can provide information about the biological significance of these responses. Here, we investigated the effects of tour boat activity on bottlenose dolphin activity patterns in Bocas del Toro, Panama over 10 weeks in 2014. Markov chain models were used to assess the effect of tour boats on dolphin behavioral transition probabilities in both control and impact scenarios. Effect of tour boat interactions was quantified by comparing transition probabilities of control and impact chains. Data were also used to construct dolphin activity budgets. Markov chain analysis revealed that in the presence of tour boats, dolphins were less likely to stay socializing and were more likely to begin traveling, and less likely to begin foraging while traveling. Additionally, activity budgets for foraging decreased and traveling increased as an effect of tour boat presence. These behavioral responses are likely to have energetic costs for individuals which may ultimately result in population-level impacts. Boat operator compliance with Panamanian whale watching regulations is urgently needed to minimize potential long-term impacts on this small, genetically distinct population and to ensure the future viability of the local tourism industry.

Macro litter distribution of the Turkish Mediterranean coasts dominated by pleasure crafts

Litters are the most pollutants in progress of the interests in marine environments. Macro litter samples were collected from 66 stations to estimate litter contribution from pleasure crafts along bays of the most Turkish touristic coasts (Antalya-Muğla) by the divers in June/July 2019. Average abundance and weight were 19 items/km2 and 18 kg/km2, respectively. The most abundant litter was plastics and the most contributors in weight were metals, followed by glass/ceramics. Abundance of the litters increased with number of pleasure crafts in active in summer. Pleasure crafts contributed most abundantly with the personal wares to the total litter, particularly in the coasts of Muğla. Litters were differentiated with interaction of region × bottom depths. The litter composition and abundance were different between region of Antalya in active mostly by tour boats and region of Muğla by private yachts. The litter types were however correlated with sea surface temperature.

Common bottlenose dolphin (Tursiops truncatus) behavior in an active narrow seaport.

The Galveston Ship Channel (GSC) is a narrow, congested waterway that supports large-scale shipping, commercial fishing, dolphin tourism, and recreation. Human activity and common bottlenose dolphins (Tursiops truncatus) converge in the GSC with potentially negative consequences on the dolphins. Elevated land-based tracking and behavioral observation of dolphins and vessels were conducted along the GSC in June-August 2013 using a digital theodolite. Positional information was used to calculate dolphin movement patterns and proximity to vessels. Log-likelihood ratio and Chi-square contingency tests were used to assess behavioral states, and generalized additive models were used to analyze movement patterns (i.e., swimming speed, reorientation rate, and linearity) relative to endogenous and exogenous factors and vessel presence. Dolphins regularly use the GSC to forage (57% of observed behavioral states) and socialize (27%), and it is not a travel corridor for accessing other favorable sites (traveling = 5%). Dolphin behavior varied significantly based on time of day, group size, calf presence, and general boat presence. When boats were present, the proportion of time dolphins spent socializing and foraging was significantly less than expected by chance. Swimming speeds increased significantly in the presence of small recreational boats, dolphin-watching tour boats, shrimp trawlers, and when tour boats and shrimp trawlers were both present. Reorientation rate increased significantly in the presence of tour boats and trawlers. Dolphin behavioral responses to vessel presence may result in decreased energy consumption due to disrupted foraging activity. Without proper management, the observed behavioral changes may be detrimental to individuals within this population in the short term, with potential long-term consequences to health and survivorship.

Participatory science and directed survey methods: A case study with odontocetes in the Maui Nui region of the Hawaiian Islands

Given the difficulties and costs often associated with surveying cetaceans, enlisting members of the public to collect data offers a promisingalternative approach. Comparison of cetacean ‘participatory science’ (also known as ‘citizen science’) data with data collected during traditionalscientific studies helps reveal the strengths and weaknesses of a participatory science approach. With a large number of vessel operators on thewater throughout the year, including dolphin-oriented tour boats, the Hawaiian Islands offer an ideal study site to employ such a dual-methodcomparison. The study aimed to enhance understanding of nearshore dolphin distributions relative to bathymetry. Operators of tour and fishingvessels within the shallow Maui Nui basin of the Hawaiian Islands were recruited to report delphinid sightings. Researchers conducted standarddolphin surveys within the same region. The participatory science approach was successful in generating a large sample size of sightings from fivedifferent species. Findings here demonstrate the potential value of participatory science and of using a multimethod approach to infer odontocetedistribution trends relative to bathymetry in areas where both methods are feasible. Important refinements for future projects are highlighted.

Density, abundance and group size of river dolphins (Inia geoffrensis and Sotalia fluviatilis) in Central Amazonia, Brazil

Given the difficulties and costs often associated with surveying cetaceans, enlisting members of the public to collect data offers a promisingalternative approach. Comparison of cetacean ‘participatory science’ (also known as ‘citizen science’) data with data collected during traditionalscientific studies helps reveal the strengths and weaknesses of a participatory science approach. With a large number of vessel operators on thewater throughout the year, including dolphin-oriented tour boats, the Hawaiian Islands offer an ideal study site to employ such a dual-methodcomparison. The study aimed to enhance understanding of nearshore dolphin distributions relative to bathymetry. Operators of tour and fishingvessels within the shallow Maui Nui basin of the Hawaiian Islands were recruited to report delphinid sightings. Researchers conducted standarddolphin surveys within the same region. The participatory science approach was successful in generating a large sample size of sightings from fivedifferent species. Findings here demonstrate the potential value of participatory science and of using a multimethod approach to infer odontocetedistribution trends relative to bathymetry in areas where both methods are feasible. Important refinements for future projects are highlighted.

2371 - ALL Aboard - Universal Access for Small Ferries and Tour Boats

The US Census American Community Survey defines Ambulatory Disabled as those people over the age of five who have serious difficulties walking or climbing stairs. The 2010 census estimates there are approximately 30.6 million Americans with Ambulatory Disabilities. The Center for Disease Control estimates 2.2 million wheelchair users in the US, leaving 28.4 million Americans who are Ambulatory Disabled, but don’t use a wheelchair. I recently became a member of this group after a stroke impaired my left side. After a year of rehabilitation, I can walk with the assistance of a single cane, but have less utility of my left arm. Six months ago, I had recovered enough mobility to travel. One activity my wife and I enjoy is environmental tourism observing rare and unique species of flora and fauna. This has included whale, dolphin, and bird watching tours. The tours themselves were enjoyable, educational, and generally not too strenuous for the mobility impaired. One problem common to all of these tours was difficulty boarding and disembarking the boats used in the tours or small ferries used to get to the tour destination. Embarkation gangways for small tour boats and ferries often consist of portable or permanent stairways that take the passenger up or down to a level that they can step across on or off the boat. Some adjustment may be needed for changes in water level or height above water of the entryway. The stairway may have two, more often one, or no railings. The ADA standards for large passenger ships do not apply to smaller tour or recreational boats. It often requires the physical assistance of one or two crew members to assist ambulatory disabled or elderly passengers on or off the boat. This not only can add trauma to an otherwise pleasant experience, but significantly slow the boarding and disembarkation times, as well as increase liability for the operator. There is a need for an affordable universal boarding system for small tour boats, recreation boats, and ferries. It should be modular, portable, and adjustable to adapt to varying tides, water levels, dock or pier heights, boat freeboard, and berth location. It should have rails on each side that extend out over the boat deck, and a transition plate to bridge the gap from the gangway to the boat.

Snorkeling and scuba diving with manta rays: encounters, norms, crowding, satisfaction, and displacement

ABSTRACTThis research note examined encounters, norms, crowding, satisfaction, and displacement among people snorkeling and scuba diving with manta rays at sites in Hawaii. These sites are popular with up to 30 tour boats and 300 participants each day. Data from a survey of 444 participants showed that 82% felt crowded by snorkelers, 78% felt crowded by boats, and 69% felt crowded by scuba divers when viewing manta rays. In reporting their norms, participants stated they would accept seeing an average of no more than 52 snorkelers, 32 scuba divers, and 11 boats at one time. However, 77% of respondents encountered more snorkelers than their norm for seeing snorkelers, 67% saw more scuba divers than they would accept, and 68% encountered more boats than their norm. These participants were more crowded, less satisfied, and more likely to become displaced (not visit again) compared to those who encountered fewer than their norms.

Short-term effects of tourism on the behaviour of common dolphins (Delphinus delphis) in the Azores

Short-term measures of behavioural responses of cetaceans to tourism operations have been used in many studies to interpret and understand potential long-term impacts of biological importance. The short-beaked common dolphin (Delphinus delphis) is the species most frequently observed in the Azores and constitutes an important component of the marine mammal tourism industry in this region. This study investigated the potential effects of tour boats on the behaviour of common dolphins off São Miguel, Azores, with particular focus on the changes in activity budget and the time required to resume activities after a tour boat interaction. Behavioural data were collected from land using a group focal-follow methodology. Markov chains were applied to analyse control and interaction sequences and to assess behavioural transition probabilities in both scenarios. In the presence of tour boats, dolphins significantly reduced the time spent foraging and increased the time engaged in other high energy activities. Dolphins also took significantly longer to resume feeding after an interaction occurred. The average bout length varied significantly between control and interaction scenarios, with foraging bouts being shorter during tour boats interactions. The results presented have management implications since feeding is a biologically critical activity. Disruption of foraging behaviour could lead to a decrease in energy intake for this population. With cetacean tourism likely to increase in the future, a precautionary approach to issuing new licences is advisable and any expansion would warrant an appropriate monitoring programme.

Manta ray tourism: interpersonal and social values conflicts, sanctions, and management

ABSTRACTScuba diving and snorkeling with manta rays (M. birostris, M. alfredi) at sites in Hawaii, USA, have become popular, with upward of 30 tour boats and 300 participants daily. This article examined whether conflicts are occurring within and between these activities and if so, what types of conflict are prevalent and how would participants respond (support restrictions, sanction others). Data from surveys of 444 participants following evening trips to view manta rays showed that 79% of snorkelers experienced in-group conflict with other snorkelers, and 53% of scuba divers reported conflict with other divers. Most conflicts were interpersonal (physical interactions among individuals interfering with experiences). Conflict behaviors included bumping into people (up to 92%), not being aware (up to 73%), and blinding people with underwater flashlights (up to 56%). There were fewer out-group conflicts between different activities (snorkelers vs. scuba divers) and minimal social values conflicts (negative preconceptions, no physical interactions among individuals). Participants supported limiting numbers of snorkelers, scuba divers, and boats, and providing education on how to behave with others. Those experiencing conflicts were more supportive of these strategies and more likely to directly sanction participants causing conflicts, but were not more likely to indirectly sanction managers and operators.

Reducing tourism's threats to biodiversity: effects of a voluntary sustainability standard and training program on 106 Latin American hotels, lodges and guesthouses

ABSTRACTThe tourism industry can negatively affect wildlife, plants and natural ecosystems through habitat destruction, pollution, over-exploitation of natural resources and visitor impacts to sensitive ecosystems. One approach to mitigate such threats is the application of voluntary sustainability standards, supported by training of tourism enterprises and verified by external audits. The Rainforest Alliance standard defines 78 criteria (requirements) for sustainable environmental, social and business practices, and has been adopted by over 600 tourism enterprises – including hotels, lodges and tour boats – in 12 countries. We examined the performance of 106 hotels in six Latin American countries against 29 of the sustainable tourism criteria most directly related to biodiversity conservation. Independent audits were used to assess hotel performance at baseline followed by a repeat assessment after training, about two years later. Mean conformance with the 29 biodiversity criteria increased significantly during this interval, from 44% to 58%. Improvements were greatest for businesses in the lowest third of performance at baseline (laggards) and smallest for hotels in the highest third (leaders). The results indicate that a voluntary sustainability standard and training program can serve both to recognize existing good actors and to drive incremental improvement in enterprises that were previously less sustainable.

Evaluating the potential disturbance from dolphin watching in Lovina, north Bali, Indonesia

[Extract] A global review of tourist visitation and expenditures associated with whale and dolphin watching industries indicated that the industry attracted 13 million tourists in 119 countries and contributed US$ 2.1 billion to the global economy in 2008 (O'Connor et al. 2009). O'Connor et al. (2009) indicated that nine of the 10 countries with the fastest rate of whale and dolphin watching industries were developing countries. Whale and dolphin watching is not without risks to targeted populations. In the short-term, the behavior of some dolphin species changes when the number of boats around a school increases (Lusseau 2003, Constantine et al. 2004, Christiansen et al. 2010). The presence of tour boats may alter the path of travel (Williams and Ashe 2007) and even force the animals to dive to avoid the boats (Schaffar et al. 2013). Interactions with dolphin watching boats may also decrease time spent foraging (Christiansen et al. 2013). In addition, dolphin watching may eventually partially displace the target population from key habitats, as demonstrated during a 19 yr research study in Shark Bay, Western Australia (Bejder et al. 2006).

Effects of boats on the surface and acoustic behaviour of an endangered population of bottlenose dolphins

Coastal cetaceans are increasingly being exposed to boats and noise as nature tourism grows. Such activity has a wide range of detrimental effects on the surface behaviour of cetaceans, but effects on their acoustic behaviour are poorly understood. We quantified the effects of tour boats and of the observing research boat on the group structure and vocal behaviour of bot- tlenose dolphins Tursiops truncatus in Doubtful Sound, New Zealand. Acoustic recordings and group follow data were collected from a 5 m research vessel, and analysed via an information- theoretic approach. Groups with mothercalf pairs were significantly less cohesive and coordi- nated when tour boats were audible. They were more vocal when boats were close and while moving away, presumably to re-establish group structure. Furthermore, groups with calves increased their whistle rates when tour boats were travelling faster, while groups without calves became quieter. Dolphins also responded to boat noise with alterations in whistle frequency and duration. These findings suggest that elevated boat noise affects communication, and groups with calves are particularly sensitive to boat presence and noise. Group structure and whistle parame- ters were affected by the research boat, highlighting the importance of accounting for observer effects in studies of tourism impacts. The particular sensitivity of groups with calves to boats has important implications for the management of impacts on this population due to its endangered status and history of low calf survival.

Effects of Tour Boats on Dolphin Activity Examined with Sensitivity Analysis of Markov Chains

In Patagonia, Argentina, watching dolphins, especially dusky dolphins (Lagenorhynchus obscurus), is a new tourist activity. Feeding time decreases and time to return to feeding after feeding is abandoned and time it takes a group of dolphins to feed increase in the presence of boats. Such effects on feeding behavior may exert energetic costs on dolphins and thus reduce an individual's survival and reproductive capacity or maybe associated with shifts in distribution. We sought to predict which behavioral changes modify the activity pattern of dolphins the most. We modeled behavioral sequences of dusky dolphins with Markov chains. We calculated transition probabilities from one activity to another and arranged them in a stochastic matrix model. The proportion of time dolphins dedicated to a given activity (activity budget) and the time it took a dolphin to resume that activity after it had been abandoned (recurrence time) were calculated. We used a sensitivity analysis of Markov chains to calculate the sensitivity of the time budget and the activity-resumption time to changes in behavioral transition probabilities. Feeding-time budget was most sensitive to changes in the probability of dolphins switching from traveling to feeding behavior and of maintaining feeding behavior. Thus, an increase in these probabilities would be associated with the largest reduction in the time dedicated to feeding. A reduction in the probability of changing from traveling to feeding would also be associated with the largest increases in the time it takes dolphins to resume feeding. To approach dolphins when they are traveling would not affect behavior less because presence of the boat may keep dolphins from returning to feeding. Our results may help operators of dolphin-watching vessels minimize negative effects on dolphins.