Phase 173 Science Report Frontier Tenerife Whale and Dolphin Conservation Project

Transcription

1 Phase 173 Science Report 2017 Frontier Tenerife Whale and Dolphin Conservation Project ABSTRACT Whale watching has increased dramatically around the world, with Tenerife seeing on average a total of 700,000 tourist whale watchers per year. This study analysed the affect of boat number on boat response and number of social behaviours exhibited by short-finned pilot whales (Globicephala macrorhynchus) and common bottlenose dolphins (Tursiops truncatus), off the southwest coast on Tenerife, Canary Islands. Number of boats did not affect the boat response or number of social behaviours performed by individuals within encounters. This could be perceived as habituation or tolerance towards human interactions, which could lead to interactions at closer proximity occurring. The outcomes from this study suggest that long term negative effects could arise as a result of repeated close proximity between humans and wild cetaceans. Therefore, showing the necessity to monitor the activity and number of boats present in the Special Area of Conservation. 1

2 TABLE OF CONTENTS INTRODUCTION 3 METHODOLOGY 5 Study Site 5 Behavioural Observations 5 Data Analysis 9 RESULTS 9 Species 10 Boat Response 10 Both Species 10 Common Bottlenose Dolphin 10 Short-finned Pilot Whale 10 Social Behaviours 11 Both Species 11 Common Bottlenose Dolphin 11 Short-finned Pilot Whale 12 DISCUSSION 12 Species 12 Boat Response 13 Social Behaviours 14 Limitations 14 Data Collection 14 Coordinates 15 Survey Platform 16 Short Duration Encounters 16 CONCLUSIONS 16 FURTHER RESEARCH 17 REFERENCES 17 2

3 INTRODUCTION Whale watching has increased dramatically around the world, with growth rates rising by more than 10% per year since the 1990s and whale watcher numbers exceeding ten million in the year 2000 alone (Ritter, 2003a; Scarpaci, et al., 2010). Within the Canary Islands, Tenerife sees on average a total of 700,000 whale watchers per year; with the money generated contributing to the local economy (Carrillo, et al., 2010). This exponential increase in tourists being within close proximity of wild cetaceans therefore raises concerns of interference of natural behaviours and the negative impacts that may occur (Ritter, 2012). The majority of the islands within the Canaries, including Tenerife, are volcanic edifices that are independent from one another. Subsequently these islands are surrounded by deep waters ( m) close to the coast, due to the narrow shelf that is present (Carrillo, et al., 2010). This factor together with average water temperature ranging between 17 and 25 C and the waters being nutrient rich (Perez-Vallazza, et al., 2008; Ritter, 2002), contributes to the reason why the cetacean species seen in this area are so diverse and of such a high number. At present there is a total of 28 cetacean species that have been sighted and recorded throughout the Canary Island archipelago, 24 of which have been seen within the waters surrounding Tenerife. Two of the four resident species within Tenerife; short-finned pilot whale (Globicephala macrorhynchus) and common bottlenose dolphin (Tursiops truncatus), are the focus species of the whale watching industry (Carrillo, et al., 2010). There are three main ports off the southwest coast, in which whale watching companies operate. They also operate in one of the 47 marine areas that Spain has classified as a SAC (Special Areas of Conservation), with this area in particular being identified as critical habitat for common bottlenose dolphin and loggerhead turtle (Caretta caretta) (Ritter, 2012). Previous studies have documented the impacts of whale watching boats on wild populations; however very few were focused on the waters surrounding Tenerife; the focus point of whale watching in the Canary Islands. Many different impacts have been documented from physical injuries to changes in behaviour (Ritter, 2012). Such influences can disrupt vital acoustic communication signals between individuals within social groups, which 3

4 sustain contact with individuals when they are out of sight (Scheer, 2013). Moreover, short term avoidance behaviours can lead to significant long term effects on individuals or whole populations of a species (Higham, et al., 2009; Ritter, 2012). As both focus species are resident within the waters surrounding Tenerife it is evident that further studies need to persist to discover whether the increase in whale watching is causing long term consequences on the populations. Ritter (2003) previously stated that within the waters of La Gomera, another island within the Canaries, the establishment of species and behaviour specific guidelines is but one way to protect cetaceans from excessive whale watching. However, despite negative impacts being present in wild cetacean populations in relation to whale watching around the world, if managed correctly tourism can help preserve biodiversity (Filla, et al., 2012; Ritter, 2012). Due to limited published papers being present in relation to the affects whale watching boats have on wild populations of cetaceans within Tenerife, this study s principal objective is to determine whether a positive, negative or neutral relationship exists. 4

5 METHODOLOGY Study Site Observations of short-finned pilot whale and common bottlenose dolphin inhabiting the waters off of the southwest coast of Tenerife (Figure 1) took place over a period of 13 weeks between 01/06/2017 and 31/08/2017. With the recording of data being conducted randomly between the hours of 10:00 and 18:00, when voluntary research assistants and members of staff were able to board the boats. There were four boats (Peter Pan, Shogun, Eden and Bonadea) being used to conduct the cetacean surveys. All of which are legal/accredited whale-watching boats that operate from both Puerto Colon in Costa Adeje and Puerto de Los Cristianos. Figure 1: Map indicating the total approximate area covered collectively by the four whale watching boats used to collect data (Maps from National Geographic Maps, 2008). Behavioural Observations In each survey, at least two researchers were onboard. One would take photographs of each individual within the pod during the encounter to record individual fins. The second researcher recorded the necessary data in the field book. 5

6 Roles would be swapped when an encounter with a new pod of cetaceans occurred. To standardise data collection, all volunteers were trained in data collection requirements before their first boat trip. All occurrence sampling was chosen as the method to record all behavioural events (Table 1) that took place during each encounter, due to the uncertainty of having an encounter whilst on the boat (Martin and Bateson 2007). Social behaviours included: breach, belly up, bow ride, surf and approach, as described by Mann and Smuts (1999) and Würsig et al. (1989). Table 1: Ethogram of cetacean behavioural events observed and recorded by researchers during encounters with short-finned pilot whales (Globicephala macrorhynchus) and common bottlenose dolphins (Tursiops truncatus). Behavioural Event Approach Scout Bow Ride Spy Hop Dive Belly Up Tail Slap Breach Surf Description One or more individuals moving and remaining close to the boat. One or more individuals in a brief approach to the boat then moving away again. Swimming in the waves at the front or back of the boat. An individual vertically raising it s head and eyes out of the water, with a vertical re-entry. Definite change of body position to dive deeper. An individual rolling over to expose its underside/belly. Lifting the tail to slap the surface of the water, creating a noise and/or splash. This behaviour can be repetitive. Any leap or jump bringing the majority of the body out of the water. Swimming quickly within and on the surface of the waves. 6

7 In the data for each encounter, records included: species, group composition, start and end time, GPS coordinates, sea state, visibility, cloud cover, behavioural state (Table 2), behavioural events, boat response, number of boats present and the encounter method. To aid data collection in the field, field books were equipped with keys listing abbreviations of species names, definitions of behavioural states, and how to record sea state, visibility and cloud cover to the appropriate standard. The initial behavioural state was defined as the behaviour being exhibited at the start of the encounter, and could fall into one of five categories: travelling, socialising, feeding, resting and milling. The number of boats present did not include the one holding the researchers and were identified as legal, illegal, fishing or jet ski. Legal and illegal boats were differentiated on the basis of their display of the Blue Boat emblem on a yellow flag; boats that did not display the flag were assumed to be unauthorised illegal whale-watching boats. Table 2: Ethogram of cetacean behavioural states observed and recorded by researchers before encounters with short-finned pilot whales (Globicephala macrorhynchus) and common bottlenose dolphins (Tursiops truncatus). Behavioural State Resting Travelling Socialising Feeding Milling Description Slow movement or stationary in a tight group, usually all facing the same direction. Sustained movement in one direction. Splashing and breaching close together. Sea bird activity, repeated surface accelerations, rapid direction changes and prey remains visible in the water. Surface in constantly varying directions in relation to each other but the group remains in one area 7

8 Boat response could be distinguished between three possible outcomes: avoidance, interaction or no response, with the outcome being determined at the end of the encounter. Group composition was recorded through researchers stating the presence of adult males, adults, juveniles and calves. The former two categories were used to a larger extent in relation to shortfinned pilot whales, due to the strong sexual dimorphism in the species; adult males have a distinctly concave fin and can therefore be differentiated from immature males and adult females. Juveniles and calves were distinguished by the presence of foetal folds on the calves sides and the close distance at which they were to an adult. The encounter method was the method in which the pod was found. If the pod of cetaceans was found as a result of the observer boat following other whale-watching boats the method was defined as boats. Similarly if they were found through a crew member searching with the naked eye or binoculars the method was search and if the captain had used a radio to communicate with other boats about cetacean sightings the method was radio. Finally, to determine sea state the Beaufort wind force scale (Table 3) was used; similarly for visibility a scale from zero to five was used, with five being a clear view of the horizon and visibility decreasing down the scale. Cloud cover was measured as a percentage inside the quadrate immediately above the observer boat; consequently, percentages could only be from zero to ten. 8

9 Table 3: Beaufort wind force scale used to determine the sea state whilst on the observer boat. Beaufort Number Sea Descriptive Terms 0 Clam (glassy) 1 Calm (rippled) 2 Smooth (wavelets) 3 Slight gentle breeze 4 Moderate breeze 5 Fresh breeze 6 Strong breeze (rough) 7 Very rough 8 Gale 9 Strong gale 10 Storm 11 Violent storm 12 Hurricane Data Analysis Kruskal-Wallis was used to determine whether the number of boats affected the boat response of the cetaceans during encounters. Whereas, regression analyses were applied to examine the influence of boat number on the number of social behaviours exhibited by individuals within encounters. As four outliers were present within the regression analyses, they were removed to prevent skewed data. Lastly, a Two-way Chi-squared test was used to determine the affect species had on boat response. The critical significance level (α) chosen for the statistical tests was RESULTS 422 encounters of differing times occurred over 91 days, with a total time of 4393 minutes spent observing during said encounters. 9

10 Species Species did not significantly affect the boat response (Two-way Chi-squared: P = 0.156, C 2 = 3.711) of individuals during encounters. Boat Response Both Species There was no statistically significant difference in the number of boats present and the boat response (Kruskal-Wallis: P = 0.797, df = 2, X 2 = 0.453) for both species of cetacean combined. Common Bottlenose Dolphin There was no statistically significant difference in the number of boats present and the boat response (Kruskal-Wallis: P = 0.385, df = 2, X 2 = 1.910) for common bottlenose dolphins. Short-finned Pilot Whale There was no statistically significant difference in the number of boats present and the boat response (Kruskal-Wallis: P = 0.215, df = 2, X 2 = 3.072) for short-finned pilot whales. 10

11 Social Behaviours Both Species There was no statistically significant relationship between the number of social behaviours exhibited and number of boats present (Linear Regression: P = 0.265, R 2 = 0.003) (Figure 2) for both species combined. Figure 2: Scatterplot representing the relationship between number of boats present and number of social behaviours performed by individuals during observed encounters. Common Bottlenose Dolphin There was no statistically significant relationship between the number of social behaviours exhibited and number of boats present (Linear Regression: P = 0.857, R 2 < 0.001) for common bottlenose dolphins. 11

12 Short-finned Pilot Whale There was no statistically significant relationship between the number of social behaviours exhibited and number of boats present (Linear Regression: P = 0.241, R 2 = 0.004) for short-finned pilot whales. DISCUSSION Species Several cetacean species that have been studied within the Canary Island archipelago have shown differing behaviours towards observers for example avoidance in dense beaked whales (Mesoplodon densirostris) (Ritter and Brederlau, 1999). Ritter (2003b) previously saw a difference in boat responses between common bottlenose dolphins and short-finned pilot whales. Common bottlenose dolphins were seen to show a large array of responses towards boats that were present, with the overall response depending on the initial behavioural state of the pod. Short-finned pilot whales did not react significantly towards boats within the encounters of his study. A similar result may have been expected in this study due to the difference in behavioural ecology of both focus species, with bottlenose dolphins being a highly social diurnal species. However, for the three month period of data collection a non-significant (P = 0.156) affect was seen between the cetacean species and boat response. Non-significant results like this have been found in several papers on mammals that have had frequent contact with tourism activities, as they have shown tolerance or habituation towards human presence (Constantine et al, 2004). Scheer et al, (2004) stated that the population of pilot whales in the Canary Islands is not habituated however this finding was in relation to human swimmers. If it is found that the wild populations of cetaceans in Tenerife have become habituated towards tourist boats it may result in further problems. For example, with the increase of tourist activity on the island in relation to whale watching (Ritter, 2003a), there could be an increase in demand for boats allowing tourists to swim with cetaceans, even though it has been prohibited since 1996 (Scheer, et al., 2014). 12

13 Boat Response This study focused on the boat response of the cetaceans, which could fall into three categories: avoidance, interaction and no response. Previous studies have shown that the type of boat present influences the behavioural response of common bottlenose dolphins, recording avoidance in the case of motorboats and no change in behaviour towards silent sailboats (La Manna et al,, 2014). In addition, significant changes were reported due to the presence of permitted vs. non-permitted dolphin watching boats (Constantine et al, 2004). In the present study there was no statistically significant difference in the number of boats present and the boat response in either the common bottlenose dolphin or the short-finned pilot whale. However, there was more of a significant affect (P = 0.215) on the pilot whales than the bottlenose dolphins (P = 0.385). This could be due to the ecology of the species, as pilot whales are nocturnal feeders and rest diurnally (Shane, 1995) meaning they are more likely to be affected by the presence of boats during critical behaviours for example resting. Moreover, it was found that 51% of the pilot whale sightings resulted in no response while 47% of the recorded bottlenose dolphins chose to interact with the boat. This high percentage of no response from short-finned pilot whales increases the chances of ship strikes occurring. Carrillo and Ritter (2010) described the Canary Islands as a hot spot for ship strikes due to the high concentration of cetaceans and boats within the area. They found 59 stranded individuals showing evidence of ship strikes between 1991 and 2007, of which 58% were found on Tenerife and 10% being shortfinned pilot whale. This, therefore, shows the need for whale watching boat captains to be extremely vigilant when in close proximity to short-finned pilot whales. 13

14 Social Behaviours One of the focuses of this study was whether or not the number of social behaviours of the short-finned pilot whales and common bottlenose dolphins changed in the presence of tourist boats. Previous studies have shown that dolphins predominantly approach and bow-ride in the presence of boats (Ritter, 2003b). However, their behaviour varies with school size, number of boats and type of boats present. As a result, resting behaviour was observed less often in small pods (less than 20 individuals) that have more than three associated boats (Constantine et al, 2004). In the case of pilot whales the trends within previous studies were less obvious although a change in behaviour was recorded especially when adult males were present in the pod (Aguilar, et al., 2001). The present study shows that the number of social behaviours had a nonsignificant relationship with the number of boats present for the two species of interest. However, Figure 2 shows a slight skew with the social behaviours increasing with the decrease of boats present. This could be due to an increase in boats and boat proximity creating a stressful environment where social behaviours are not normally performed, evidence for this was suggested in a paper by Aguilar, et al. (2001) that focused on bottlenose dolphins. Therefore, it should be considered that a large congregation of boats should be avoided when interacting with cetaceans, due to the heightened stress factors present. Limitations Data Collection Human error (Type 1 error) in this data is introduced through the researchers. These data were collected by Frontier volunteers of different backgrounds and therefore differing levels of experience. All volunteers received the same training before any data collection was allowed to take place, however learning continued as volunteers becoming more vigilant and accurate with observations and recordings as time through the project passed. 14

15 The data collection method used for this study was observational data; therefore human error is an important variable to consider during analysis. Both bottlenose dolphins and short-finned pilot whales tend to travel in groups of approximately and respectively. It can therefore be difficult to accurately determine how many different individuals are in the pod, in particular when they are showing social behaviours. However, this is not the case for solitary individuals, usually the bottlenose dolphin (Bloom, 1991). Other variables that are difficult to identify are age and sex of the individuals when there is no size reference. In this case, large females travelling alone can easily be mistaken for males. When recording encounters it may have been possible for behavioural states to be mistakenly recorded as another, for example, milling may be mistaken for travelling. Therefore increasing the type 1 error potentially found within the data set. This error is also seen when recording boat responses, for example, mistaking the behavioural event of dive for a boat response of no response rather than avoidance. Differences in observer vision may introduce an additional source of error, as not all volunteers can identify the animals and their behaviour with the same accuracy with varying distances. In addition, it can be difficult to distinguish legal from illegal whale watching boats as the Blue Boat flag can not always be clearly seen, it is not always present on legal boats. On various occasions, legal boats not following regulations (splitting up pods and not switching the engines off) were observed. Coordinates A further problem encountered during the study was the flawed recording of the coordinates. The volunteers using iphones did not initially know how to alter the coordinate format on their devices and as a result had not been recording the correct coordinates. Therefore, only data collected from August onwards will be used for the distribution map in the next phase report, proceeding the correction of the recorded coordinates. 15

16 Survey Platform The data collected for analysis was collected whilst on legal commercial whale watching boats: Peter Pan, Shogun, Eden and Bonadea. As the researchers conducted their studies within these vessels amongst tourists during the summer months, there are a wide variety of limitations with the data that need to be taken into consideration. Bejder and Samuels (2003) stated that collecting data using this platform can question how reliable the data are and limits how this data can be interpreted. On commercial boats the behaviours that can be seen are restricted to whether or not the individual/individuals can tolerate proximity to the vessel, in order to visualise these behaviours (Bejder and Samuels, 2003). Other behaviours shown by the individuals further away from the vessel may not be seen and therefore will not be recorded, hence creating bias within the data set. Short Duration Encounters The final limitation found when collecting this data is whether short duration encounters should be entered into the final data analysis. With short encounters it is possible to misinterpret the behaviour shown or miss other long term behaviours and responses, making it less likely to accurately record pod composition, all behaviours and responses without error. Scheer et al. (2004) and Hofmann et al. (2004) avoided this by only including encounters which were >3 minutes in duration with a mean duration of 4.26 minutes, to ensure all data collected is accurate. CONCLUSIONS In this study we found that the number of boats did not have a significant effect on the number of social behaviours or boat response in either bottlenose dolphins or short-finned pilot whales. This could be perceived as tolerance or habituation, which could further lead to more long term negative effects. Therefore, this shows the necessity to monitor the activity and number of boats present in the Special Area of Conservation. 16

17 FURTHER RESEARCH For the next phase report we plan to investigate several aspects. The focus point will be on different behavioural responses to the cetacean distribution, time of day and the differences in the boat captains approach to respecting the whale watching regulations. Furthermore, the frequency of behavioural state, avoidance behaviour in relation to the boats and a distribution map will be analysed respectively. REFERENCES Aguilar, N., Díaz, F., Carrillo, M., Brito, A., Barquín, J., Alayón, P., Falcón, J. and González, G Evidence of disturbance of protected cetacean populations in the Canary Islands. Article: International Whaling Commission. London, United Kingdom Bejder, L. and Samuels, A Evaluating the effects of nature-based tourism on cetaceans. Marine Mammals: Fisheries, Tourism and Management Issues, 1, pp Bloom, P The diary of a wild, solitary, bottlenose dolphin (Tursiops truncatus), resident off Amble off the north Northumberland coast of England, from April 1987 to January Aquatic Mammals, 17(3), pp Carrillo, M. and Ritter, F Increasing numbers of ship strikes in the Canary Islands: proposals for immediate action to reduce risk of vessel-whale collisions. Journal Cetacean Research and Management, 11(2), pp Carrillo, M., Pérez-Vallazza, C., Álvarez-Váquez, R Cetacean diversity and distribution off Tenerife (Canary Islands). Marine Biodiversity Records, 3, pp. 1-9 Constantine, R., Brunton, D H. and Dennis, T Dolphin-watching tour boats change bottlenose dolphin (Tursiops truncatus) behaviour. Biological Conservation, 117, pp

18 Filla, G. F., Oliveira, C. I. B., Gonçalves, J. M. and Monteiro-Filho, E. L. A The economic evaluation of estuarine dolphin (Sotalia guianensis) watching tourism in the Cananéia region, south-eastern Brazil. International Journal of Green Economics, 6(1), pp Higham, J. E. S., Bejder, L. and Lusseau, D An integrated and adaptive management model to address the long-term sustainability of tourist interactions with cetaceans. Environmental Conservation, 35(4), pp Hofmann B., Scheer M. and Behr I. P Underwater behaviors of shortfinned pilot whales (Globicephala macrorhynchus) off Tenerife. Mammalia, 68(2-3), pp La Manna, G., Manghi, M. and Sarà, G Monitoring the habitat use of common Bottlenose Dolphins (Tursiops truncatus) using passive acoustics in a Mediterranean marine protected area. Mediterranean Marine Science, 15(2), pp Martin, P. and Batesan, P Measuring behaviour. Third Edition. Cambridge: Cambridge University Press Mann, J. and Smuts, B Behavioral development in wild bottlenose dolphin newborns (Tursiops sp.). Behaviour, 136, pp National Geographic Maps PDF Quads. [Online] Available at: < a96bcdc2631ef10ad9d&home=true&zoom=true&scale=false&search=tr ue&theme=light> [Accessed 05/09/2017] Ritter, F. and Brederlau, B Behavioural observations of dense beaked whales (Mesoplodon densirostris) off La Gomera, Canary Islands ( ). Aquatic Mammals, 25(2), pp

19 Ritter, F Behavioural observations of rough-toothed dolphins (Steno bredanensis) off La Gomera, Canary Islands ( ) with special reference to their interactions with humans. Aquatic Mammals, 28(1), pp Ritter, F. 2003a. Boat-related behaviours of cetaceans as a tool for the development of species-specific whale watching guidelines. Poster: Annual Conference of the European Cetacean Society. Gran Canaria, Spain Ritter, F. 2003b. Interactions of Cetaceans with Whale Watching Boats Implications for the Management of Whale Watching Tourism. Ritter, F Model for a Marine Protected Area designed for sustainable Whale Watching Tourism off the oceanic Island of La Gomera (Canary Islands). Berlin: M.E.E.R.e.V. Perez-Vallazza, C., Alvarez-Vazquez, R., Cardona, L., Pintado, C. and Hernandez-Brito, J Cetacean diversity at the west coast of La Palma Island (Canary Islands). Journal of the Marine Biological Association of the United Kingdom, 88(6), pp Scarpaci, C., Lück, M. and Parsons, E. C. M Recent advances in whale-watching research: Tourism in Marine Environments, 6(1), pp Scheer, M., Hofmann B. and Behr, I. P Ethogram of selected behaviors initiated by free-ranging short-finned pilot whales (Globicephala macrorhynchus) and directed to human swimmers during open water encounters. Anthrozoös, 17(3), pp

20 Scheer, M Call vocalizations recorded among short-finned pilot whales (Globicephala macrorhynchus) off Tenerife, Canary Islands. Aquatic Mammals, 39(3), pp Scheer, M., Sá Alves, L. C. P., Ritter, F., Azevedo, A. F. and Andriolo, A Behaviors of botos and short-finned pilot whales during close encounters with humans: management implications derived from ethograms for food provisioned versus unhabituated cetaceans. In: J.B Samuels (Ed.) Dolphins: Ecology, behavior and conservation strategies. New York: Nova Science Publishers. pp Shane, S. H Behavior patterns of pilot whales and Risso s dolphins off Santa Catalina Island, California. Aquatic Mammals, 21(3), pp Würsig, B., Dorsey, E. M., Richardson, W. J. and Wells, R. S Feeding, aerial and play behaviours of the bowhead whale, Balaena mysticetus, summering in the Beaufort Sea. Aquatic Mammals, 15(1), pp