Boat activity on the behaviours of short-finned pilot whales (Globicephala macrorhynchus) and common bottlenose dolphins (Tursiops truncatus)

Transcription

1 Boat activity on the behaviours of short-finned pilot whales (Globicephala macrorhynchus) and common bottlenose dolphins (Tursiops truncatus) TRW Phase 181 Science Report 01/12/ /02/2018 Negulescu, R., Patel, T. & Foster, C. Staff Project Coordinator (PC) Research Officer (RO) Assistant Research Officer (ARO) Ramona Negulescu (RN) Tinessa Patel (TP) Carolyn Foster (CF)

2 Abstract The whale-watching industry in Tenerife has increased exponentially over the past few years, with the introduction of the Barco Azul flag. There are 4 resident species of the Canary Islands, 2 of which are of particular interest for this research: the short-finned pilot whale (Globicephala macrorhynchus) and the common bottlenose dolphin (Tursiops truncatus). Through the use of data collected during boat surveys on whale-watching vessels in South Tenerife, the behaviours of the 2 target species were recorded in respect to their initial behavioural state on encounters, any behavioural events during the encounters and behavioural response toward the boats; against the boat activity (proxy: number of boats present). The necessary data was statistically analysed by the means of one-way ANOVA and linear regression. The result showed a mixture of significant and insignificant results based on the 6 different combinations of boats and species ; however, behaviours did change depending on how many boats were present. A variety of factors could have caused the results seen, such as boat proximity to the cetaceans, boat size, engine size, human vocalisations etc. One main limitation to this methodology however is human error, perspectives of multiple boats during one encounter could alter the data and cause multicollinearity in the process. It was concluded that boat activity does not have a big effect on cetacean behaviour during the months this survey was conducted. However, if this survey were to be conducted during busy tourist months such as April to May, and July to August, the result may be different. 2

3 Contents Abstract... 2 Contents Introduction Why research in the Canary Islands? Whale-watching in Tenerife UNESCO Protected area Anthropogenic affects Boat noise Boat collisions Species seen during the research period Delphinidae Balaenopteridae Aims & objectives Rationale & hypotheses Methodology Training procedure Data collection Peter Pan and Bahriyeli Shogun Data input Statistical analysis Results Behavioural state Short-finned pilot whales (Globicephala macrorhynchus) Common bottlenose dolphin (Tursiops truncatus) Behavioural events Short-finned pilot whales (Globicephala macrorhynchus) Common bottlenose dolphin (Tursiops truncatus) Boat response Short-finned pilot whales (Globicephala macrorhynchus) Common bottlenose dolphin (Tursiops truncatus) Discussion Behavioural state Short-finned pilot whales (Globicephala macrorhynchus)

4 Common bottlenose dolphins (Tursiops truncatus) Behavioural events Short-finned pilot whales (Globicephala macrorhynchus) Common bottlenose dolphins (Tursiops truncatus) Boat Response Short-finned pilot whales (Globicephala macrorhynchus) Common bottlenose dolphins (Tursiops truncatus) Limitations Datasets Methodology Sightings Conclusion References

5 1. Introduction 1.1. Why research in the Canary Islands? Tenerife s cetacean diversity is the highest known in the occidental part of the Canary Archipelago (Carrillo et al., 2010) and due to the waters around the islands containing a complex oceanographic system, a great variety of cetacean species are drawn to the area by increases in phytoplankton (Pérez-Vallazza et al., 2008). A past study reported that the waters around Tenerife also provide an excellent habitat for Odontocetes (Ritter, 2003a) and the numerous submarine canyons; with water depths of >3,000 m (Krastel et al., 2001) create prime hunting environments for Short-finned pilot whales. The island of Tenerife enjoys good weather on 315 of 365 days a year, with resident species of whales and dolphins reliably close to shore year-round (Hoyt, 1995). As a result, an opportunity was created for whale-watching activities to become established in the area, as both an ecotourism and socio-economic industry Whale-watching in Tenerife Since their introduction in the Canary Islands, whale-watching excursions have gone on to attract the highest number of cetacean watchers within the African region (O'Connor et al., 2009). Tenerife is the main contributor to the total number of whalewatching boats seen within the Canary Islands, with approximately 1.7 million whalewatchers annually in the area (Hoyt, 2005). In 2003, where boat numbers and passenger numbers peaked, there were approximately 41 whale-watching boats in the Canary Islands, 36 of which were in Tenerife alone; and an average of 107 tourists per boat trip (Elejabeitia & Urquiola, 2009). By 2008 however this had dropped to a total of 37 in the Canary Islands, with 26 of them being licensed in Tenerife and an average passenger capacity on each boat trip of 90.6 (Elejabeitia & Urquiola, 2009). This made up to approximately 85% of the total number of whale watchers in the Canary Islands (O'Connor et al., 2009) UNESCO Protected area The waters around the south of Tenerife are home to a variety of marine fauna, including the loggerhead turtle (Caretta caretta) and bottlenose dolphin (Tursiops truncatus). As a measure designed to help in the conservation of such species, three 5

6 Special Areas of Conservation (SAC s) were declared in the area, covering a total of 6,648Ha (Aguilar et al, 2001); in such areas tourist boats are restricted in certain actions, like approaching the cetaceans, in order to try and ease anthropogenic pressures on the animals. Furthermore, eco-tourism companies pay to take part in courses in which they learn the appropriate actions to take when approaching cetaceans and during encounters. By the end of this, the company will be given a Blue Boat flag, of which they must legally fly on all excursions demonstrating that they follow the rules, to try and reduce the levels of anthropogenic disturbance upon the animals Anthropogenic affects Boat noise Despite efforts to impose restrictions of tourist boats, resident and transient species of cetaceans around Tenerife still face direct and indirect anthropogenic threats and disturbances from other forms of boat traffic, including jet-skis, fishing vessels and high-speed ferries such as the modern ferry Benchijigua Express (Fred Olsen & Armas), that crosses from Tenerife to La Gomera (gomera.info, 2018). The noise pollution created by boat engines and motorised boats can disrupt the echolocation system that cetaceans such as whales and dolphins use to communicate, hunt for prey and escape from predators (Au, 1993). Contrary to common belief, engine noise is not the main cause of audio disruption upon cetaceans. Although all cetacean species have a different frequency at which they communicate with one-another, most of these are of a higher frequency than the boat engine noise created, for this reason, mainly those few species that communicate with low frequency vocalisations are disrupted by such anthropogenic noise (Ross, 1976). According to past research, odontocete species such as the short-finned pilot whales and the bottlenose dolphins are affected more by the cavitation created by boats, rather than engine noise (Ross, 1976). Cavitation is the term used to describe the process in which bubbles are formed in the water by the oscillation of the propeller, then burst against the solid surfaces of the boat. The vibrations created when the bubbles burst are at a high enough frequency that it lies in the frequency range of odontocete sounds. These, therefore have the ability to interrupt the signals on the receiving end of the communications or in worse cases stop it completely (Marten & Marler, 1977). 6

7 Boat collisions It is clear that boat traffic has many detrimental impacts on cetaceans. The most danger to the animals comes in the form of collisions and ship strikes, these incidents kill increasing numbers of cetaceans; particularly females and calves, whilst leaving many others injured (Aguilar et al., 2001). Many markings, distinct cuts and notches found on cetacean dorsal fins are made on impact of vessels; making identification of individuals possible, in particular for the short-finned pilot whales (Figure 1 a & b). However, this can also cause blunt-force trauma in these animals, which can sometimes be very distinct even from whale-watching vessels. Such encounters can cause mortality in cetacean individuals, making boat activity one of the highest causes of population decline seen in these animals (Wells & Scott, 1997). The main threat to cetaceans comes from the fast ferries. Prior to the introduction of this ferry line; between 1985 and 1998, there was a total of 5 recorded collisions between vessels and cetaceans within the islands of Tenerife and La Gomera. This number soon increased to 9 collisions after the introduction of the fast ferries between 1999 and 2000 (Aguilar et al., 2001). Whale-watching boats do not pose as much of a threat to cetaceans in the form of boat collisions as they can control their speed more accurately than that of ferries. They also give themselves enough time to scan their surroundings and stop if necessary when cetaceans are around, opposed to jet-skis, which are usually travelling too quickly to notice and stop for these animals. 7

8 a) b) Figure 1. 2 individuals seen regularly from whale-watching boats around Tenerife, believed to have been victim to boat collisions causing distinct shapes to their dorsal fins. Both of these images were taken by Frontier Research Assistants upon Bahriyeli. a) Male pilot whale, known locally as Indio (January, 2018), b) Common bottlenose dolphin, of undetermined sex (February, 2018) Species seen during the research period The study focuses on two species that are resident in the southern waters of Tenerife: the common bottlenose dolphin (Tursiops truncatus) and the short-finned pilot whale (Globicephala macrorhynchus). However, information about more species has been collected due to occasional sightings Delphinidae Most of the species observed on boat surveys during Phase 181 belong to the most diverse family of cetaceans: Delphinidae. Class: Mammalia Order: Cetacea Suborder: Odontoceti Family: Delphinidae This consists of aquatic mammals which, like all cetaceans, have a streamlined body with two pectoral fins showing hyperphalangy, a dorsal fin of various shapes 8

9 and two flukes that are used for propulsion (Grzimek, 2003). There is a wide variety of morphological characteristics in terms of size, shape and coloration within this family, many of which are adaptations to their habitat or to their hunting technique (Braulik et al., 2014). The pelvis is vestigial and the nostrils have migrated on the top of the head in order to ease breathing. There are 34 species of delphinids, classified in 17 genera (Grzimek, 2003), with a worldwide distribution in extremely diverse habitats. They can be found in waters of different salinity and temperatures in all oceans and seas (Braulik et al., 2014). They are highly sociable animals that generally live in groups and display a wide array of behaviours, many of which thought to have only the purpose of pure entertainment. They are known to breach, to surf and bow-ride as well as to use other species or inanimate objects for play (Braulik et al., 2014). They use a series of whistles and clicks in order to communicate and for echolocation, which helps them navigate and find prey. Short-finned pilot whales (Globicephala macrorhynchus) Figure 2. Short-finned pilot whales. Images taken by Tim Borrill & Doug Perrine, T respectively (arkive.org). The short-finned pilot whale is one of the most commonly seen cetacean species off the south of Tenerife (Figure 2). This species is easy to recognize due to its rounded head, with a large melon and lack of a prominent rostrum. In adults, the coloration is dark grey-black, with a lighter coloured saddle and an anchor-shaped pattern on the ventral side. There is a pronounced sexual dimorphism, with the males growing longer in length than females and possessing a larger melon and a larger, more falcate dorsal fin (Marrero Pérez, et al., 2016). It is very similar to its close relative, the long finned pilot whale (Globicephala melas) that has in comparison a darker coloration and longer pectoral 9

10 fins. However, the range of the two species doesn t overlap, G. macrorhynchus preferring warmer temperate and tropical waters (Marrero Pérez et al., 2016), while G. melas is more likely to be found in colder habitats, at higher latitudes (Grzimek, 2003). The information about the diet of short-finned pilot whales comes mainly from the analysis of the stomach contents of dead cetaceans. These proved that G.macrorhynchus feeds primarily on cephalopods like squid. However, fish remains can also be found in their stomachs (Marrero Pérez et al., 2016). The tendency of pilot whales for mass stranding is not fully understood but a recent study (Yunus et al., 2017) has shown that they can be caused by a series of medical conditions or external factors like collisions with boats or an altered sonar. On the IUCN Red List (IUCN, 2018), G. macrorhynchus is listed as data deficient. Common bottlenose dolphins (Tursiops truncatus) Figure 3. Common bottlenose dolphin. Image by Teo Lucas (Gigante Azul). The bottlenose dolphin has been the best known species of delphinid from ancient times (Figure 3). It appears in Roman and Greek mythology (Carwardine, 2006) and it is currently the most frequently displayed species in aquaria all over the world. In the wild, it has a worldwide distribution in temperate to tropical waters and, according to its geographic location it shows a high diversity of morphological features (Grzimek, 2003). In general it is known to reach lengths of up to 3.8 meters and it is easily identifiable due to its robust body, with a short, stubby rostrum and large melon (Carwardine, 2006). Just like most other delphinids, it has a 10

11 countershading coloration, with a dark grey dorsal cape and a lighter grey white ventral side (Grzimek, 2003). Its diet is diverse and can consist of fish, squid or crustaceans. It reproduces every 3-6 years, when the females give birth to one calf after a one year gestation (Carwardine, 2006). The promiscuous mating system leads to competition among males (Grzimek, 2003). On the IUCN Red List (IUCN, 2018), the bottlenose dolphin is listed as least concern. Atlantic spotted dolphins (Stenella frontalis) The Atlantic spotted dolphins share many morphological similarities with the pantropical spotted dolphins (S. attenuata) (Figure 4). The calves are born greywhite, without spots (Peres dos Santos et al., 2016) and go through a series of different colour phases before they reach maturity, with the spots starting to appear when the dolphins are between 2 and 6 years old (Herzing, 1997). Some individuals remain unspotted throughout their lives (WDC, n.d.), a feature that can make them resemble T.truncatus. However, the smaller body size is an efficient indicator of the species. While the bottlenose dolphins can grow up to 4 meters (Grzimek, 2003), the Atlantic spotted dolphins can only reach 2.3 meters (WDC, n.d.). As their name suggests, they are found in the Atlantic Ocean, in temperate and tropical regions. Their diet consists of small fish, squid and other invertebrates (WDC, n.d.). S. frontalis is a very sociable and acrobatic cetacean. It is often observed near the shore in groups of 5-15 individuals, offshore in very large numbers (WDC, n.d.), and sometimes it also interacts with other species. In the south of Tenerife it has been seen together with T. truncatus and D. delphis. The Atlantic spotted dolphins mate during all the stages of development but the calves are generally born during spring and autumn (Herzing, 1997). The Atlantic spotted dolphin is listed data deficient on the IUCN Red List (IUCN, 2018). 11 Figure 4. The Atlantic spotted dolphins commonly seen during this phase. Images taken by Teo Lucas (Gigante Azul).

12 Striped dolphins (Stenella coeruleoalba) The striped dolphin is a rather small species (Figure 5), reaching a maximum length of 2.4 meters and weighing up to 150 kilograms (Grzimek, 2003). Its common name refers to the dark coloured stripe on its flanks that delimits the white-pinkish ventral side from the bluish-grey back (Carwardine, 2006). Another stripe goes from the eye to the pectoral fin and there s a lateral blaze towards the dorsal fin (Carwardine, 2006). It is a cosmopolite species found in the Pacific, Atlantic and Indian Oceans, with a preference for warm temperate to tropical habitats (Grzimek, 2003), where it feeds mainly on squid and fish (Carwardine, 2006). Breeding occurs every 4 years and one calf is born tail first after a gestation period of months (Carwardine, 2006). Striped dolphins are highly sociable and are often found in large groups counting up to 500 individuals (WDC, n.d.). They display behaviours such as bow-riding, surfing and breaching, that are common to other cetacean species, as well as rototailing which is specific to S. coeruleoalba. This consists of leaping high in the air and rotating the tail before touching the water again (Carwardine, 2006). Although it still faces threats due to drift-net fishing, pollution and habitat degradation, S. coeruleoalba s conservation status on the IUCN Red List is least concern (IUCN, 2018). Figure 5. Striped dolphins in Tenerife. Images taken by Todd Passer & Lisa Steiner (arkive.org). Short beaked common dolphins (Delphinus delphis) The common dolphin is another one of the smaller species of cetaceans observed around the South of Tenerife during the past three months (Figure 6). It reaches a 12

13 maximum length of 2.4 meters and a weight of around 136 kg (Grzimek, 2003). It is easily recognizable by its black rostrum, the yellow hourglass-shaped pattern on the flanks and the black margins around the eyes (Grzimek, 2003). Regarding its distribution, the short-beaked common dolphin can be encountered in the temperate to tropical waters of the Atlantic, Pacific and Indian Oceans (WDC, n.d.), with a high abundance in the Mediterranean Sea and the Black Sea (Grzimek, 2003). Its diet consists of small fish and squid and common dolphins have been observed hunting in groups (WDC, n.d.). The female gives birth to one calf after a gestation period of months (Carwardine, 2006). The short beaked common dolphin is a very social and acrobatic species and it lives in groups that can range from 10 to 500 individuals (Grzimek, 2003). In Tenerife it was seen on different occasions in the same interaction with Atlantic spotted dolphins (Stenella frontalis). Although the population trend remains unknown, the species is known to be very abundant in all the regions it inhabits and it is listed as least concern on the IUCN Red List (IUCN, 2018). Figure 6. The short beaked common dolphins. Images taken by Teo Lucas (Gigante Azul) Balaenopteridae Class: Mammalia Order: Cetacea Suborder: Mysticeti Family: Balaenopteridae 13

14 The Balaenopteridae family consists of 8 species belonging to 2 genera (Braulik et al., 2014) that can be found worldwide, in coastal to pelagic waters. Also known as rorquals, the members of this family have a distinctive series of skin grooves on the ventral side, from the mandible to the umbilicus (Braulik et al., 2014). This feature allows for a specialized feeding technique called lunge feeding, which consists of the whale accelerating with the mouth open and engulfing a large quantity of water that is later filtered, leaving the prey items on the baleen plates (Shadwick et al., 2017) Unlike other baleen whales, the balaenopterids have a very streamlined shape and large heads that are dorso-ventrally compressed. The dorsal fin is generally small, positioned towards the back and the pectoral fins contain only four digits (Braulik et al., 2014). Most rorqual species are very well known for their migratory lifestyles and the different use of their habitats. They prefer feeding at higher latitudes during the summer months and move to lower latitudes in order to breed in winter (Braulik et al., 2014). Bryde s/sei whale (Balaenoptera edeni/balaenoptera borealis) Figure 7. Top row: Sei whales, taken by Glen Tepke & Doug Perrine, respectively. Bottom row: Bryde s whale, images taken by Teo Lucas (Gigante Azul). 14

15 The two species are extremely similar in appearance and without a closer look at their head region they are extremely difficult to distinguish (Figure 7). The three ridges present on the rostrum of B.edeni compared to only one on B. borealis represent the key feature for identification. (Braulik et al., 2014) They reach a length of around 15 meters and they have a similar coloration: blue-black dorsally and white or yellow on the ventral side (Grzimek, 2003). Both species share the same habitat, populating worldwide pelagic waters in tropical and temperate areas (Grzimek, 2003), with little interest in approaching the coast (Braulik et al., 2014). For this reason, together with their migratory patterns, interactions with either B. edeni or B. borealis are generally rare in the waters of southern Tenerife. They are known to feed primarily on small fish, copepods and amphipods (Grzimek, 2003). While Sei whales mate during winter, in Bryde s whales breeding takes place all year long. One calf is born after a gestation period of approximately one year and it will be fed by the mother for six to eight months (Braulik et al., 2014). The conservation status of the two species is different. The Sei whale is listed endangered on the IUCN Red List, while the Bryde s whale is data deficient (IUCN, 2018) Aims & objectives The aim of this research was to distinguish trends, if any, in bottlenose dolphin and pilot whale individuals in respect to the increasing boat activity during the encounters; the number of other boats present acted as a proxy for this. This was done by statistical analysis of data collected from boat surveys that took place between December 2017 and February 2018, to look for any statistical explanation of what was seen Rationale & hypotheses A significant change in behaviour caused by the presence of more whale watching boats might indicate habituation or stress. The behavioural events displayed during 15

16 interactions with cetaceans can show the short-term effect the presence of the boats has on the animal (Lusseau, 2006). Previous studies have considered the possibility that these short-term changes in behaviour could have long-term consequences, especially if vital behaviours like feeding are disrupted by boats (Hastie, et al., 2003). It was also discovered that each cetacean species behaves in a different way in the presence of boats. Analysing this information could be useful for whale watching companies that could be given species-specific and behaviour specific guidelines in order to better adapt to each interaction (Ritter, 2003b), and this way reducing the negative impact that tourism might have on the cetaceans. It was firstly hypothesised that as boat activity increased, the behavioural states of the cetaceans would lean toward a travelling state. Secondly, as boat activity increased, the number of avoidance behavioural events would increase. Finally, as boat activity increased so would the number of cases where an avoidance boat response was shown by the cetaceans. 2. Methodology 2.1. Training procedure In order to ensure the accuracy of data collection, all volunteers go through a training session at the beginning of their stay. It takes place every Monday for the new arrivals and it consists of the following components: A brief risk assessment in which volunteers are instructed in basic safety procedures and correct behaviour whilst on the project and especially on the boats; An introductory presentation that describes Frontier s Mission Statement, aims and objectives, as well as information about the island geography, fauna, flora and local attractions; A general presentation about cetaceans, including characteristics, evolution, comparison and contrast of the two orders (Mysticeti and Odontoceti), a brief description of the species that are found in the Canary waters, with an accent on the two species of interest: Tursiops truncatus and Globicephala macrorhynchus; Data and photo ID training in which volunteers are presented with the methods of data collection applied on the boat surveys and with the aims and importance of photo ID. 16

17 The training session is performed by two staff members (generally the PC and the RO) and is always adapted to the level of knowledge and understanding of each volunteer group. The aim is to ensure that all volunteers, regardless of their background, are prepared for the boat surveys. In order to assess their ability to correctly identify the most commonly seen species, at the end of the Cetacean presentation the volunteers have an identification quiz, in which they are presented with various pictures of whales and dolphins for which they need to give the common name. They are also tested on their ability to correctly identify group size, group composition, behavioural states and behavioural events with the help of various videos taken on previous boat trips. After they are trained in data collection and photo ID techniques, the volunteers are asked to practice on mock data sets and data sheets in order to familiarize with the procedures and to eliminate any possible errors. They are also asked to process mock photographs, as a method of practicing the photo ID Data collection For each boat survey a pair of volunteers is sent out with a camera and a clipboard with the data sheet template (Table 1). General Information is collected at the beginning of the survey. This includes the date, the name of the boat and the name of the Research Assistants that are participating. The weather conditions are also recorded. The cloud cover is estimated between 0 and 10%, the sea state is assessed using the Beaufort scale (values between 0 and 12) and the visibility is given a code between 0 and 5 (5 representing the clearest conditions). At the beginning of each interaction, the Start Time and GPS location are recorded on the data sheet. Once the species has been identified, the RAs can move on to identify the behavioural state (Table 2), group size and group composition (total, males, adults, juveniles and calves). During each interaction, the cetaceans might display various behaviours, which fall into 9 categories: approach, scout, bow ride, surf, spy hop, dive, belly up, tail slap and breach (Table 3). The number of behavioural events is also recorded on the data sheet. Data about the whale-watching boats is also collected on each interaction. The approach method refers to the way the cetaceans were encountered: by searching, radio or by observing the presence of other boats. If other boats are present, they need to be marked as accredited or legal, unaccredited or illegal, fishing boats or jet- 17

18 Boats Composition GPS Time TRW Phase Report 181 Negulescu, R., Patel, T. & Foster, C. skis. At the end of each encounter, the time is recorded again, as well as the response of the cetaceans to the boat: interaction, no response or avoidance. Table 1. Table given to Assistant Researchers for data collection upon Peter Pan, Bahriyeli and Shogun. Date: Boat: Research Assistants : Trip Time: Cloud Cover: Sea State: Visibility: Encounter Start End 28 o N -16 o W Behavioural events Species Behavioural State Total Males Adults Juveniles Calves Approach Scout Bow-Ride Spy-Hop Belly-Up Tail Slap Dive Surf Breach Illegal Legal Fishing Jet Skis Method Boat Response Notes 18

19 Table 2. Descriptions of the behavioural states recorded on boat surveys. Behavioural State Resting Description Slow movement or stationary as a tight group, usually facing the same direction. Milling Surface constantly varying directions in relation to each other but group remains in one area. Travelling Sustained movement in one direction. Socializing Splashing and breaching close together. Feeding Repeated surface accelerations, rapid direction changes, visible prey, and possible seabird activity. Table 3. Descriptions of behavioural events recorded during encounters on boat surveys. Behavioural Event Approach Scout Bow Ride Surf Spy-Hop Dive Belly Up Tail Slap Breach Description One or more individuals moving towards and remaining close to the boat. One or more individuals show a brief approach followed by diving/swimming away shortly after. Individuals swimming within the waves created by the boat on either the front or back of the vessel. Swimming quickly on the surface of the waves. An individual vertically raising its head and eyes put of the water, with a vertical re-entry. Definite change of body position to descend deeper. An individual rolling over to expose its pectoral fins/belly. Lifting the fluke out of the water and slapping it on the surface, creates a noise and/or splash, often the action is repetitive. Individuals jump with most/all of its body out of the water. 19

20 Peter Pan and Bahriyeli Two of the whale-watching boats that are used for Frontier boat surveys are Peter Pan, belonging to Neptuno Sea Company and Bahriyeli, belonging to Mar de Ons. Both boats go out of Puerto de Los Cristianos and have a similar route that is illustrated by figure 8. Figure 8. Approximate route for morning Peter Pan trips, using GeoTracker on Peter Pan 13/11/2017. Peter Pan usually offers two trips a day. The first one lasts for three hours, between 10:00 and 13:00 while the second trip is shorter, two hours between 13:30 and 15:30. Occasionally, when Shogun is under repair, Peter Pan can follow the route to Los Gigantes instead or offer an additional trip. 2 volunteers are placed on the boat on the morning trip and, when the tourist number allows it, on the afternoon one as well. With the data used being collected between 01/12/2017 and 16/02/2018. Bahriyeli is a new boat that Frontier Research Assistants started to use at the beginning of January It offers three whale-watching trips every day, leaving at 11:00, 13:00 and 15:00. Up to four volunteers are allowed to go on the boat at a time and to stay for the entire day. However, due to the large amount of data and photo ID required after each boat trip, each couple or group of volunteers is only permitted to stay for one trip. With the data used being collected between 17/01/2018 and 06/02/

21 Shogun Shogun is another boat that belongs to Neptuno Sea Company. It performs one trip a day that lasts for 5 hours, starting from Puerto Colon and stopping in Los Gigantes for lunch before returning to Costa Adeje. An approximate route is figure 9. Just like on Peter Pan, 2 Frontier volunteers are allowed aboard Shogun each day. With the data used being collected between 01/12/2017 and 16/02/2018. Figure 9. An approximate route for Shogun trips, using GeoTracker on 07/11/ Data input After each boat trip, the Research Assistants are expected to introduce the collected data into the database of the organisation. This is a GoogleSheets document, with a separate spreadsheet for each boat, which is updated on a daily basis and safely stored online in order to prevent any data loss. After inputting the data, the interaction code for each encounter is used to create a new folder for the photo ID. The photo processing is done using Picasa on 2 Frontier 21

22 computers (one for Neptuno and one for Bahriyeli) and each folder is backed up on an external hard drive Statistical analysis The data from 01/12/2017 to 16/02/2018 were obtained and organised within an excel document. The data were sorted for each hypothesis, leaving only the necessary columns for each of the three hypotheses, each hypothesis had three documents (one for each boat) with three sheets within in (one for each species). Any rows of data (individual interactions) that had empty fields, such as no behavioural state or no boat response state were removed. There were six different combinations of boat and species used for each hypothesis; a) Peter Pan: Pilot whales, b) Peter Pan: Bottlenose dolphins, c) Shogun: Pilot whales, d) Bottlenose dolphins, e) Bahriyeli: Pilot whales and f) Bahriyeli: Bottlenose dolphins. Hence, each hypothesis yielded 6 individual graphs. SPSS statistical software was used to generate the graphical data and to statistically analyse the data for each hypothesis. The two main statistical tests used for these hypotheses were one-way ANOVA s, correlations and linear regressions. All statistical tests were matched with visual representations of the data in the form of either bar graphs or line graphs. 22

23 3. Results 3.1. Behavioural state Short-finned pilot whales (Globicephala macrorhynchus) a) b) c) Figure 10. Behavioural state of short-finned pilot whale groups and the number of boats present (not including the boat used as the research platform) during encounters on a) Peter Pan, b) Shogun and c) Bahriyeli. Error bars ±1 S.E. 23

24 During short-finned pilot whale encounters recorded aboard Peter Pan, the highest number of boats seen on one encounter was 6 boats. This only occurred on one encounter where the pilot whales were approached whilst milling, which too showed the highest mean number of boats present during all encounters for the behavioural states recorded (Figure 10a). The lowest number of boats present during encounters were 0 boats (excluding the research platform boat). These instances were seen throughout interactions of all behavioural states. However, there was only one interaction recorded where the whales were socialising with 0 other boats present; for this reason the data bar does not show and the error bar is equal to 0. The error bars that are present on the remaining behavioural states overlap slightly, therefore significance between the mean number of boats and behavioural states seen on interaction cannot be defined (Figure 10a). For this reason, assumptions for a one-way ANOVA were tested. QQ-plots were used to test for normal distribution which yielded a normal distribution. There were outliers in the data, nevertheless, ANOVA deals well with outliers therefore possible to continue with type-1 error in the results. A Levene s test for homogeneity was conducted showing insignificance, therefore the assumption for homogeneity can be accepted (Levene s test: F=1.893, df=5, p=0.118). The ANOVA was carried out showing insignificance between the 2 variables during pilot whale encounters from Peter Pan (One-way ANOVA: df=5, Mean Square=0.886, F=0.870, p=0.506). On encounters from Shogun, the short-finned pilot whales had the highest number of boats seen (5), during 1 resting encounter. The lowest number of boats present during pilot whale encounters on Shogun was 0, during resting and travelling behaviours (Figure 10b). The highest mean number of boats was seen for resting pilot whales where there was a mean number of 2 boats per interaction. The lowest was travelling where there was a mean number of <1 (Figure 10b). The error bars overlap, therefore a one-way ANOVA was conducted. All assumptions were tested; qq-plots and outliers were accounted for, and homogeneity was tested through means of a Levene s test (Levene s test: F=1.158, df=4, p=0.356). The one-way ANOVA showed to be insignificant (One-way ANOVA: df=4, Mean Square=0.394, F=0.556, p=0.697). Finally, the short-finned pilot whale encounters from Bahriyeli showed a maximum number of boats present on one encounter as 4 vessels, the lowest being 0. The highest mean number of boats during pilot whale interactions was seen on encounters where the group were resting on approach, the lowest mean number of boats was seen for travelling encounters for pilot whales (Figure 10c). The error bars that have been calculated also overlap with one-another, therefore further statistical 24

25 analyses was necessary. A one-way ANOVA was conducted after the appropriate assumptions were tested. The data was normally distributed; tested by qq-plots, outliers were distinguished using boxplots which were accounted for in the test, and homogeneity of the dataset was tested through the use of a Levene s test (Levene s test: F=0.640, df=6, p=0.697). The ANOVA was conducted showing an insignificance between mean number of boats per interaction and behavioural state of the cetaceans on approach (One-way ANOVA: df=6, Mean Square=0.328, F=0.590, p=0.734) Common bottlenose dolphin (Tursiops truncatus) During Bottlenose dolphin encounters recorded from Peter Pan, the highest number of boats seen during one interaction was 3 boats, with a minimum of 0 boats (excluding the research platform boat). The behavioural state that was witnessed with the highest mean number of boats present was milling (Figure 11a). With the lowest mean number of boats present was seen during travelling. There were no instances where the bottlenose dolphins were approached whilst resting during this time period, therefore the bar is obsolete (Figure 11a). The error bars on the remaining behavioural states overlap indicating the need for a one-way ANOVA. Like for the pilot whales, normality was tested using qq-plots; showing that the data was normally distributed. There were no outliers within this data set. Homogeneity was tested through a Levene s test, showing an insignificant p-value, therefore accepting the assumption of homogeneity in the dataset (Levene s test: F=2.166, df=3, p=0.113). Finally, the ANOVA was conducted showing an insignificant difference between the two factors (One-way ANOVA: df=3, Mean Square=4.327, F=1.842, p=0.161). The data for bottlenose dolphin encounters on Shogun was then analysed. The dolphins recorded on this platform only showed a total of three of the five behavioural states logged; travelling, milling and socialising. The highest number of boats seen in one encounter was six vessels, during a socialising interaction (Figure 11b). Milling showed the lowest mean number of boats. The error bars, too, overlap therefore the assumptions of a one-way ANOVA were tested, the data was normally distributed; tested through the use of qq-plots. There were little outliers which the ANOVA test accounted for in type-1 error, and the Levene s test for homogeneity showed to be insignificant therefore the data were homogenous (Levene s test: F=1.519, df=3, p=0/269). The one-way ANOVA conducted also 25

26 proved to be insignificant (One-way ANOVA: df=3, Mean Square=3.588, F=1.563, p=0.259). 26

27 a) b) c) Figure 11. Behavioural state of bottlenose dolphin groups and the number of boats present (not including the boat used as the research platform) during encounters on a) Peter Pan, b) Shogun and c) Bahriyeli. Error bars ±1 S.E. 27

28 Finally, bottlenose dolphins on Bahriyeli were seen to have a higher mean number of boats present during encounters where they were feeding, upon approach of the whale-watching vessel. The lowest mean number of boats during interactions were seen during travelling encounters (Figure 11c). Although there is no bar present for resting dolphins from Bahriyeli, there were encounters for this behavioural state, however all interactions had 0 boats present, therefore an error bar of 0. There were no instances where the bottlenose dolphins were socialising with one-another on approach of the vessel (Figure 11c). The error bars present overlap, hence, the assumptions for a one-way ANOVA were tested prior to conducting the test. QQ-plots showed that the data used was normally distributed. Boxplots showed there to be no outliers, and homogeneity of the dataset was tested using Levene s test, proving insignificant, therefore the assumption of homogeneity can be accepted test (Levene s test: F=0.871, df=3, p=0.488). The ANOVA test proved to show an insignificant difference between the mean number of boats present during each encounter and the behavioural state shown by the individuals on such encounters (One-way ANOVA: df=3, Mean Square=0.393, F=0.321, p=0.810) Behavioural events Short-finned pilot whales (Globicephala macrorhynchus) On Peter Pan, the pilot whales had shown a variety of different behavioural events during encounters. The most frequent behavioural event recorded was dive, showing avoidance in particular to when there were 0 other boats present (Figure 12a). The least common behavioural event seen during pilot whale encounters on Peter Pan was scout (another avoidance behaviour), which peaked at 1 other boat present during the interaction, returning back to 0 occasions at 2 boats present (Figure 12a). The general trend for the number of behavioural events decreased as the number of boats present during encounters increased (Figure 12a). The assumptions for correlation and regression were tested and accepted before conducting the tests between the number of boats and the overall number of behavioural events seen (Pearson correlation: Correlation statistic=-0.517, p<0.001; Linear regression: 28

29 R=0.520, R 2 =0.271). The regression showed a moderate, but negative degree of correlation between the two variables with little variance in the dependent variable. 29

30 a) b) c) Figure 12. The frequencies of each behavioural event of the short-finned pilot whales, recorded upon each boat; a) Peter Pan, b) Shogun and c) Bahriyeli. Error bars ±1 S.E. 30

31 From Shogun, the most frequent behavioural event seen from the pilot whales was approach towards the vessel (Figure 12b). The least common events seen were scout, bow-ride and tail slap, where no such events were recorded in the study period off of this vessel (Figure 12b). Once all necessary assumptions were tested and met, a correlation and regression analysis was conducted, findings of which suggested the correlation between number of events seen and the number of boats present was low, but negative, with slight variance in the dependent variable (Pearson correlation: Correlation statistic= , p=0.010; Linear regression: R=0.355, R 2 =0.126). Upon Bahriyeli, the pilot whales had shown a variety of different behavioural events, the modal event recorded was bow-ride with a peak of 4 occasions with 2 other whale-watching boats present. The least common events were those that were not performed, tail slap, scout, spy-hop, surf, breach and belly-up (Figure 12c). The regression analysis was carried out on this dataset to see if there is any relationship between the number of boats present and the number of behavioural events seen. The assumptions were tested and accepted, correlation and regression were conducted (Pearson correlation= , p=0.818; Linear regression: R=0.243, R 2 =0.059). Showing a low degree of negative correlation with very little variance in the dependent variable Common bottlenose dolphin (Tursiops truncatus) For the bottlenose dolphins seen upon Peter Pan there was no definite pattern seen between the number of boats present during interactions and the number of behavioural events seen (Figure 13a). The modal behavioural event seen performed by bottlenose dolphins during encounters was breaching, which peaked on encounters where there were 0 boats present. The least common behavioural event shown by this species was approach, where only 1 individual was seen to approach when there were 2 boats present, and no other case (Figure 13a). Appropriate assumptions were tested and a correlation and regression followed, showing a low, but negative degree of correlation between the number of boats present and the number of behavioural events performed, and little variance in the dependent variable (Pearson correlation: Correlation statistic= , p=0.509; Linear regression: R=0.114, R 2 =0.013). 31

32 a) b) c) Figure 13. The frequencies of each behavioural event of the common bottlenose dolphins, recorded upon each boat; a) Peter Pan, b) Shogun and c) Bahriyeli. Error bars ±1 S.E. 32

33 The number of bottlenose encounters recorded upon Shogun was less than that of the other boats used to collect data, therefore the number of events seen, and in total is lower. The most common behavioural event shown by bottlenose dolphins on this vessel was breaching; with a peak at 2 boats present, and the least common event of those recorded in the bottlenose dolphins was diving, which occurred only once when 1 other boat was present during the encounter (Figure 13b). As like the previous combinations of boat and species, the assumptions for a both correlation and linear regression were tested and accepted before conducting the statistical tests. The tests stated that there was a low, but negative degree of correlation between the 2 variables, with little variance within the dependant variable (Pearson correlation: Correlation statistic= , p=0.008; Linear regression: R=0.335, R 2 =0.112). For the bottlenose dolphins seen from Bahriyeli the most common behavioural event seen during this research period was scout which peaked at a total of 5 accounts with 0 other boats present, the least common events seen were belly-up, surf and spy-hop (Figure 13c). The correlation and regression assumptions were tested and accepted. These tests also showed a low degree of negative correlation with very little variance within the dependent variable (Pearson correlation: Correlation statistic= , p=0.970; Linear regression: R=0.178, R 2 =0.032) Boat response Short-finned pilot whales (Globicephala macrorhynchus) Boat responses of the cetaceans were tested against the number of boats present during the encounters recorded during this phase period. On Peter Pan the pilot whale had a higher no response to the boats when high in abundance. There were however, encounters when the number of boats present was kept to a minimum (0) (Figure 14a). The error bars overlapped a one-way ANOVA was conducted. The assumptions of an ANOVA were tested; normality was accepted by the use of qqplots, and homogeneity was accepted using a Levene s test (Levene s test: F=1.112, df=5, p=0.363). The ANOVA proved to be insignificant, therefore no significant difference between the mean number of boats and the bot response of pilot whales seen from Peter Pan (df=5, Mean square=0.439, F=1.256, p=0.294). 33

34 a) b) c) Figure 14. Boat response of the short-finned pilot whales during encounters on, a) Peter Pan, b) Shogun and c) Bahriyeli. Error bars ±1 S.E. 34

35 The pilot whales encountered on Shogun showed a higher frequency of avoidance encounter than compared to any other research vessel. There was a mean number of 4 boats present during these avoidance responses from pilot whales compared to a mean of approximately 1 boat present during interaction and no response, responses (Figure 14b). The error bars for the mean number of boats present during interaction encounters and no response encounters overlapped almost fully, therefore statistical analysis was necessary (Figure 14b). The assumptions were tested by the use of qq-plots and a Levene s test for homogeneity (Levene s test: F=2.531, df=4, p=0.076). The one-way ANOVA conducted proved insignificant, therefore there was no significance between the mean number of boats present during encounters and the boat response shown by the pilot whales (Oneway ANOVA: df=4, Mean square=0.914, F=2.631, p=0.069). The last platform to be tested was Bahriyeli. Firstly, the pilot whales recorded upon this vessel. Both, interaction and no response had a mean number of around 2 boats during the encounters. On the other hand, the avoidance boat response had the lowest mean number of boats during the encounters. The error bars for this combination also overlapped slightly, therefore an ANOVA was conducted to specify the significance, if any between the 2 variables (Figure 14c). The assumptions were tested, a variety of qq-plots were used to test normality within the variables, which was then accepted. The Levene s test for homogeneity in the data was accepted (Levene s test: F=1.699, df=6, p=0.185). The ANOVA test however proved insignificant (One-way ANOVA: df=6, Mean square=0.290, F=0.677, p=0.671) Common bottlenose dolphin (Tursiops truncatus) The bottlenose dolphins recorded off of Peter Pan showed an opposite response compared to that of the pilot whales seen off the same vessel. The dolphins interacted most with a higher number of boats present, and showed least response with the lowest number of boats present (Figure 15a). Like the pilot whales, the error bars overlapped, therefore an ANOVA was carried out to see if there is any significant difference between the 2 variables (Figure 15a). The assumptions were tested, normality was tested and accepted using qq-plots, and homogeneity in the data was tested using a Levene s test (Levene s test: F=1.139, df=3, p=0.350). The ANOVA returned insignificant, showing no significant difference between the variables (One-way ANOVA: df=3, Mean square=0.099, F=0.236, p=0.871). 35

36 a) b) c) Figure 15. Boat response of the short-finned pilot whales during encounters on, a) Peter Pan, b) Shogun and c) Bahriyeli. Error bars ±1 S.E. 36