Behavioural Response and Fine-Scale Movement of South West Tenerife’s Cetaceans with

Vessel Traffic

South Tenerife, Canary Islands, Spain

TRW Phase 201 Science Report

Davies, K., Bresciani, C., Lucas, J.,

1st January – 16th March 2020

Abstract

Legislation exists in many popular whale watching destinations to enforce boat etiquette around

cetaceans. In the southwest of Tenerife, legal certification is required for all whale watching

vessels, yet illegal boats without certification continue to interact with cetaceans. Additionally,

according to the Barco- Azul certification, no more than two boats should be present during a

whale-watching interaction, yet vessel traffic is increasing. This study investigated the

behavioural responses of three of the most locally encountered species; the short-finned pilot

whale Globicephala macrorhynchus, bottlenose dolphin Tursiops truncates and Atlantic spotted

dolphin Stenella frontali in response to increasing vessel traffic and the presence of illegal boats.

It additionally used supplementary land-based observations to quantify how specific factors

related to the boat’s impact on the presence of bottlenose dolphins at coastal fish farms. This

report identified that interactive behaviour decreased for both short-finned pilot whales and

Atlantic spotted dolphins as boat numbers increased. Illegal boats did not cause any more of a

negative behavioural effect than those certified by the Barco Azul, raising concerns over the

current level of enforcement and compliance to whale watching regulations with certified boats.

Whilst analysing specific boat factors during land-based observation, there was a marked 76%

decline in cetacean presence when boats were moving fast, compared to when they were

stationary. This study additionally identified that short-finned pilot whales may have a higher

sensitivity to whale watching, displaying more avoidance behaviours than other local species.

Further work should therefore include examining the specific behaviour of both legal and illegal

boats with respect to cetacean behaviour to better inform local policy, whilst including the

potential for species-specific whale watching requirements.

Contents 1. Introduction 1

1.1 Frontier 1

1.2 Tenerife 1

1.3 Marine Zone 1

1.4 Geology 2

1.5 Nutrient Dynamics & Oceanography 2

2. Cetaceans 3

2.1 Common bottlenose dolphin (Tursiops truncatus) 3

2.2 Short-finned pilot whales (Globicephala macrorhynchus) 4

2.3 Atlantic spotted dolphin (Stenella frontalis) 5

2.4 Bryde’s whale (Balaenoptera edeni) 7

3. Threats to cetaceans 8

3.1 Tourism 8

3.2 Ship collisions 8

3.3 Noise pollution 9

4. Fieldwork Training 10

4.1 General Introduction 10

4.2 Risk Assessment 11

4.3 Cetaceans in Tenerife 11

4.4 Data Collection Methods 11

4.5 Mysticeti Whale Identification 12

4.6 Darwin Catalogue in Tenerife 12

5. General Project Information 13

5.1 Survey Area 13

5.2 General Aims 14

6. Research Project 16

6.1 Gaps in Knowledge 16

6.2 Aims/Objectives 18

6.3 Materials and Methods 19

6.31 Boat-Based Fieldwork 19

6.32 Land-Based Fieldwork 21

6.4 Data Analysis 21

7. Results 22

7.1 Behavioural Responses 22

7.2. Species Specific Differences 26

7.3 Cetacean Presence with Vessel Traffic Around Fish Farms 27

8. Discussion 29

8.1 Behavioural Responses 29

8.2 Species Specific Differences 30

8.3 Cetacean Presence with Vessel Traffic Around Fish Farms 30

9. Conclusions/ Further Work 31

10. References 32

11. Appendices 40

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Field Staff

Principal Investigator (PI) Katrina Davies (KD)

Assistant Research Officer (ARO) Chiara Bresciani

Assistant Research Officer (ARO) Jordan Lucas

Project Manager (PM) Awena Sangster

1. Introduction

1.1 Frontier Frontier was established as a non-profit conservation project in 1989 and has since developed

into a Non-Governmental Organisation (“NGO”) with projects spanning 5 continents. The key

focus of Frontier is centred around conserving and protecting biodiversity and the natural

environment. Frontier aims to create a sustainable interaction between the environment and

economy, engaging with the general public and key stakeholders to ensure that the natural

environment is safeguarded and managed sustainably.

Frontier’s mission in Tenerife is centred on whale and dolphin conservation, assessing the

impacts of marine traffic on the resident and migratory species of cetaceans. There is a particular

emphasis on the interactions between cetaceans and the current ecotourism model. The

objectives of this project are to inform policy and procedures, ensuring that future encounters do

not negatively impact the species found locally.

1.2 Tenerife

Tenerife is the largest island in the Canary archipelago, which is situated in the eastern Atlantic

Ocean, 80 miles off the coast of Morocco, Africa (Troll, et al., 2016). The Island has a land mass

of 2,034 km2 which supports a population of roughly 900,000 permanent inhabitants. However,

each year around 5,000,000 tourists visit the Island (Bowler, 2018). The popularity of Tenerife as

a holiday destination incurs many of the same challenges experienced in small island states,

which often rely heavily on their marine zone for economic development, transportation and as a

source of nutrition. This in turn can lead to the erosion of various marine ecosystems and their

associated biodiversity (Bland, et al., 2019; Meriweather, et al., 2018).

1.3 Marine Zone

As an island, Tenerife is reliant on its marine zone as a source of economic growth. The Canary

Islands have practiced mariculture, a branch of aquaculture which focuses on rearing marine

species, and is well known for its production of Great Atlantic Sea Bass. Whilst mariculture is a

lucrative financial venture, there have been several studies linking mariculture to cases of

eutrophication, red tides and antibiotic resistance in the immediate vicinity (Meng, et al., 2019;

Zang, et al., 2020).

The Canary archipelago is a key shipping lane for global trade. As a result, the wider marine

zone is subject to sustained traffic (Tovar, et al., 2015). The potential effects of traffic on an

area’s biodiversity can be severe in the absence of correct spatial planning and management

(Coomber, et al., 2016).

Ecotourism is a well-established market in Tenerife, with several companies capitalising on the

rich biodiversity found locally. Whale-watching vessel interactions with cetaceans can have

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mixed results (Mallard, 2019). Whilst they offer opportunities for public engagement and citizen

science (Vieria, et al., 2018), they pose the threat of collision, disturbance and pollution (Matear,

et al., 2019). Ensuring these vessels are managed with suitable regulations and policies is key

to the future conservation of target species (Breen, et al., 2017).

Tenerife is exposed to the Atlantic Ocean which is an extremely high energy environment. Due

to extensive, unimpeded stretches of ocean, fetch and swell combine to generate large waves

(Campos, et al., 2018). It has been suggested that Tenerife could lower its carbon footprint by

investing in wind and offshore wave technologies. Both of which would be greatly benefited by

the oceanic and atmospheric conditions generated locally. However, marine spatial planning

would require extensive research (Veigas, et al., 2013, Wiess, et al., 2018).

1.4 Geology Tenerife has a complex volcanic history, with some of the Islands early formations being dated at

7,000,000 years old. Over time, the early formations experienced several periods of tectonic

activity, followed by prolonged quiescent periods during which time the site would be

geologically dormant. The geomorphology of Tenerife is a direct result of this activity, which is

heavily linked to Tenerife’s proximity to the Mid-Atlantic Ridge, a geologically active site which

further influenced the creation of several other Atlantic Islands (Huang, et al., 2018).

One of the key characteristics of Tenerife is the extremely deep water that surrounds the island,

which occurs as a result of tectonic activity, also leading to the creation of Mount Teide.

Summiting at 7,500 meters from the ocean floor, Mount Teide is now a dormant volcano which

played a key historical role in enriching the area with nutrients (Ancochea, et al., 1990; del

Porto, et al., 2013). The type of tectonic activity which led to the creation of Tenerife is

characterised by coastal waters that drop off to extreme depths. Consequently, depths

surrounding Tenerife reach the bathypelagic (1,000 – 3,999 meters), a byssopelagic (4,000 –

5,999 meters), and hadalpelagic (<6,000 meters) zones (Troll, et al., 2016). These depths support

several species of megafauna as they can easily transition between the photic and aphotic zones

of the water column (Puig-Lozano, et al., 2015).

1.5 Nutrient Dynamics & Oceanography

The waters surrounding Tenerife are well known sites of upwelling, a process that brings

nutrients from the deep ocean up into the photic zone. This process creates optimum conditions

for phytoplankton blooms to occur (Sebastián, et al., 2004). Upwelling negates biologically

limiting factors by stimulating the region’s nutrient dynamics. It also serves as a buffer against

climate change. The process which transports the cooler, nutrient rich waters to the surface

regulates the temperature of the water column. This reduces warming and its potential impact on

the region’s biodiversity (Varela, et al., 2018).

Due to Tenerife’s proximity to the Western Saharan Desert, the region is frequently showered in

Saharan dust which is transported via prevailing winds and other atmospheric processes. It has

been suggested that the frequency of the Saharan dust deposition surrounding Tenerife will

increase as a direct result of climate change (Hernandez, et al., 2018; Rodríguez, et al., ND). The

process of atmospheric deposition delivers several key nutrients to the photic zone of the water

column, increasing primary production even when introduced to oligotrophic environments

(Zhang, et al., 2019).

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The consolidation of upwelling and atmospheric deposition creates ideal conditions for

phytoplankton blooms, which form the base of euphotic food chains. This feature is one of the

primary reasons why Tenerife has extensive marine biodiversity (Ohde, et al., 2010).

2. Cetaceans

Given the great abundance and diversity of nutrients in the waters around the Island, Tenerife has

been shown to provide an ideal habitat for cetaceans. Out of the 28 species that have been

sighted in the Canary Archipelago, 24 of them have been observed around Tenerife, representing

more than 85% of all cetacean species (Carrillo, et al., 2010). Although most of these species are

migrant, waters around Tenerife provide a permanent habitat to four odontocete (toothed whale)

cetacean species: the short-finned pilot whale (Globicephala macrorhynchus), bottlenose dolphin

(Tursiops truncatus), sperm whale (Physeter macrocephalus) and Risso’s dolphin (Grampus

griseus) (Francisco-Ortega, et al., 2009). Of these four permanent species, only short-finned pilot

whales and bottlenose dolphins are regularly sighted in the marine strip where we operate (from

Punta de Teno to Punta de Rasca). In addition, two migrant species, the Atlantic spotted dolphin

(Stenella frontalis) and the mysticete (baleen whale) Bryde’s whale (Balaenoptera edeni) have

been sighted in phase 194. For the purpose of simplicity, only the species observed in this phase

will be described in the present report.

2.1 Common bottlenose dolphin (Tursiops truncatus)

Common bottlenose dolphins are widespread in temperate and tropical waters worldwide. They

have been generally found either in coastal or pelagic populations, with some differences in

morphology and social structure existing between the two ecotypes (Perez-Alvarez, et al., 2018;

Saayman, et al., 1972; Figure 1.1 ). These delphinds have a robust body and are medium-sized

(220-230 cm), although they present a remarkable variation in body size according to location,

with the largest individuals reported so far being observed in the north-eastern Atlantic (350-410

cm; Connor, et al., 2000). Their coloration can vary from slate grey to charcoal, with an overall

lighter pigmentation in the ventral part of the body (Figure 1.1). Life-span is generally long and

averages 40-50 years, although females may live longer (Connor, et al., 2000). Bottlenose

dolphins prey on a variety of fish as well as molluscs such as squids and octopuses (Bearzi, et al.,

2009), which can explain their abundance and fidelity in our study area.

This species lives in highly fluid fission-fusion societies, where individuals in a population tend

to aggregate in smaller groups with changing composition and size over time (Connor, et al.,

2000). Although groups are mostly characterized by short-term associations, an increasing

number of studies have reported strong long-term bonds between individuals of the same group,

especially in resident and stable populations (Lusseau, et al., 2003; Perez-Alvarez, et al., 2018).

These bonds are of great importance for individuals’ survival, as they have been shown to boost

inclusive fitness gains (e.g. through cooperation in the acquisition and defence of resources)

(Moller, et al., 2006).

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The bottlenose dolphin is listed as ‘Least Concern’ on the IUCN Red List, yet is still exposed to

a variety of anthropogenic threats (Connor, et al., 2000). For instance, they have been found to

alter their social dynamics and grouping patterns according to human fishing activities (Chilvers

& Corkeron, 2001; Daura-Jorge, et al., 2012; Kovacs, et al., 2017), limit their resting behaviour

in the presence of numerous whale-watching boats (Constantine, et al., 2004), and can suffer

from reduced prey availability due to overfishing and habitat degradation (Jackson, et al., 2001).

Figure 1.1: General appearance of common bottlenose dolphins and differences in morphology between the coastal

and offshore ecotype (Wells and Scott, 2018).

2.2 Short-finned pilot whales (Globicephala macrorhynchus) The short-finned pilot whale is widely distributed in the temperate circumtropical waters ,

generally preferring deeper offshore areas where they can hunt their primary prey of squid

(Olson, 2009; Taylor, et al., 2011). This species has a characteristic appearance with a large

bulbous head with no obvious rostrum and a dark grey colour (Pérez, et al., 2017; Figure 1.2).

They present a clear sexual dimorphism, with adult males reaching a length of up to 1 meter

greater than their female counterparts and showing an overall thicker and more hooked dorsal fin

(Mahaffy, et al., 2015). Short-finned pilot whales are the most commonly sighted cetacean

around the south-eastern waters of Tenerife, where they are spotted resting or travelling at the

surface during the day. This is made possible by their lateralized sleeping behaviour (i.e.,

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unihemispheric slow wave sleep, (Lyamin, et al., 2008) that allows them to breathe and be

constantly vigilant.

They are thought to generally live in multigenerational matrilineal societies, with little or no

natal dispersal (Heimlich-Boran, 1993; Mahaffy, et al., 2015). According to a few relatively

recent studies, individuals within populations might show different degrees of site fidelity, with

some groups being resident year-round while others exhibit some degree of migration between

different sites (Alves, et al., 2013; Heimlich-Boran, 1993; Mahaffy, et al., 2015). Although still

little is known about the population in Tenerife, it is thought to be mainly composed of resident

individuals with transient groups merging according to migrant season (Soto, et al., 2008).

Hopefully current efforts in photo-ID will help better understand the dynamics of this population

and benefit the current knowledge of this species, which at present is still classified as ‘Data

deficient’ on the IUCN Red List. In the study area, potential threats to the species are ship

collisions and anthropogenic noise pollution (Ritter, 2010; Jensen, et al., 2011). Pilot whales are

known to leave their group during deep foraging dives and rely on tonal calls and echolocation to

communicate with group companions, something that can be heavily affected by vessel and boat

noise (Soto, et al., 2008; Jensen, et al., 2011).

Figure 1.2: a Short-finned pilot whale (Globicephala macrorhynchus) which has a typical appearance with a large

bulbous head with no obvious rostrum and a dark grey colour (Pérez, et al., 2017)

2.3 Atlantic spotted dolphin (Stenella frontalis) The Atlantic spotted dolphin is known to be distributed in the warm and warm-temperate waters

of the Atlantic Ocean. They generally inhabit the continental shelf but are documented to

occasionally come to very shallow waters as well (Perrin, et al., 1994; Mills & Rademacher,

1996). Although appearing morphologically similar to the bottlenose dolphin, this species starts

showing dark ventral spots from the onset of weaning, which increase in size and number as they

grow into adulthood, as well as light dorsal spots (Perrin, et al.,1994;sta.uwi.edu, 2015; Figure

1.3). Atlantic spotted dolphins generally live in big pods of up to a hundred individuals, which

have been observed to frequently split into smaller and stable cooperating sub-groups, for

instance when they feed on big balls of fish or cephalopods (Perrin, et al., 1994; Fertl & Würsig,

1995).

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Although there is a well-documented population of resident spotted dolphins in the Bahamas

(Elliser & Herzing, 2012; Elliser & Herzing, 2014), the species is considered to be mainly

migrant (Perrin, et al., 1994). In the Canary Islands it has been observed year-round, with peaks

in winter and spring (Ritter, 2001; Pérez-Vallazza, et al., 2008; Carrillo, et al., 2010). In a

relatively recent study in the south-west area off the coast of Tenerife, Stenella frontalis was the

fourth most sighted cetacean, with calves and/or neonates present in a considerably high

percentage of sightings (60.61%) (Carrillo, et al., 2010). This suggests that the species may use

the area as a breeding site, which further stresses the importance of reducing the potential threats

related to boat traffic and noise pollution.

Figure 1.3: Morphology of juvenile and adult Atlantic spotted dolphin (Stenella frontalis). (sta.uwi.edu, 2015).

Figure 1.3: Morphology of juvenile and adult Atlantic spotted dolphin (Stenella frontalis). (sta.uwi.edu, 2015).

7

2.4 Bryde’s whale (Balaenoptera edeni) Bryde’s whale (Figure 1.4) is a baleen whale distributed in warm and temperate tropical waters

worldwide at latitudes between 40°N and 40°S (Paterson & Van Dyck, 1988; Constantine, et al.,

2015). This species has a length between 13-15 m (Figure 1.4), and is thought to comprise of two

different ecotypes (Constantine, et al., 2015; ewt.org.za, 2019). Since this species has been

observed to feed primarily on schooling fish (e.g. Pacific sardine and thread herring) and rely

less on zooplankton compared to other baleen whales (Paterson & Van Dyck, 1988; Tershy,

1993), it is suggested that it may not have the need to undertake extensive migrations, exploiting

local food resources year-round with little movements (Ritter & Neumann, 2006; Constantine, et

al., 2015).

Around the Canary Archipelago the Bryde’s whale has been sighted relatively frequently (Ritter,

2001; Pérez-Vallazza, et al., 2008; Carrillo, et al., 2010), with an constant occurrence in the

waters off La Gomera from spring to autumn 2005 (Ritter & Neumann, 2006), and the highest

number of sightings among mysticetes off the coast of Tenerife in a study from 1997-2006

(Carrillo, et al., 2010).

Much like other cetaceans, this species can suffer from noise pollution, habitat degradation due

to human overexploitation and risk of being caught by fishing nets. However, from a study

conducted in the Hauraki Gulf (northeastern New Zealand) it emerged that the major threat for

this species might be vessel collision (Constantine, et al., 2015), which stresses the importance of

monitoring the increasingly intense boat traffic inTenerife.

Figure 1.4: Overall appearance of Bryde’s whale (Baloenoptera edeni). (wwhandbook.iwc.int).

8

3. Threats to cetaceans

3.1 Tourism The Canary Islands have become a popular tourist destination, attracting several millions of

tourists every year (Ritter, 2010). Consequently, boat traffic has dramatically increased, from

high speed ferries to touristic and non-commercial boats (Carrillo, et al., 2010; Ritter, 2010).

Given the rich species diversity and abundance in the area, cetaceans are extremely important for

the overall economy of the islands, with whale-watching activities attracting more than 700,000

people every year (Carrillo, et al., 2010).

Despite the rapid growth of the whale-watching industry worldwide, still little is known about

the short and long-term consequences of tourist boats on cetacean behaviour (Constantine, et al.,

2004). However, it is likely that resident populations such Tursiops truncatus and Globicephala

macrorhynchus off the southwest coast of Tenerife might be more affected than migrant groups

by the continuous exposure to legal and illegal (recreational non-permitted boats) tourism.

Research in different areas of the world suggest that cetaceans might be adversely affected. For

instance, different species have been found to alter their behaviour in the presence of multiple

boats, by reducing their resting in favour of more erratic behaviour (e.g. milling) or increasing

swimming speed when more boats were present (Lusseau, 2003; Constantine, et al., 2004;

Stensland & Berggren, 2007); avoiding the area when high boat densities are reached (Allen &

Read, 2000) and changing group size, composition and compactness (Nowacek, et al., 2001;

Mattson & Thomas, 2005). These alterations are likely to impact a populations’ health in the

long-term, especially when there is a reduction in important behaviours such as resting or

feeding (Constantine, et al., 2003; Stensland & Berggren, 2007).

In the light of this, our current work in the southwest area of Tenerife might help in gaining a

better overview of how the resident cetacean populations are responding to the increasing boat

traffic, and, if necessary, how this can be better managed.

3.2 Ship collisions Another threat strictly related to tourism is the increasing collisions of cetaceans with

commercial and non-commercial vessels. This issue is of major concern especially in geographic

areas where there is a wide overlap between intense maritime traffic and a high density of

cetaceans (Ritter, 2010; Ritter, 2012; Constantine, et al., 2015), such as the Canary Archipelago.

In recent years, boats travelling at speeds higher than 14-15 knots has been increasing

dramatically worldwide, with a predictable consequential growth in the number of fatal

collisions with cetaceans (Carrillo & Ritter, 2010). The types of vessels involved in strikes

comprise cargo or cruise ships, tankers, whale-watching vessels, navy ships and especially high-

speed ferries and sailing boats (Carrillo & Ritter, 2010; Ritter, 2012). Most of the seven Canary

Islands are connected by ferries, and in 2007 a total of eight ferries travelling at speeds higher

than 21 knots were operating (Ritter, 2010), a number that seemed to remain constant until 2019.

Although both mysticetes and odontocetes can be involved in ship strikes (Van Waerebeek,

2007), studies worldwide suggest that particularly vulnerable species are those that swim slowly

and spend more time at the surface, with higher mortality rates reported for large whales

9

(Panigada, et al., 2006; Carrillo & Ritter, 2010; Van Waerebeek, 2007; Ritter, 2012; Constantine,

et al., 2015).

In Tenerife, Globicephala macrorhynchus can be especially affected by vessel collisions, as this

species is commonly seen resting at the surface during the day. A study from 2010, (Carrillo &

Ritter, 2010) found that out of the total number of carcasses attributed to whale-vessel strikes,

10% were short-finned pilot whales.

Given that cetaceans have considerably low rates of reproduction, increased mortality due to

collisions with ships can have an extremely negative impact on populations, with individuals

dying before reaching sexual maturity (Constantine, et al., 2015). This is why the International

Whaling Commission (IWC) set up a Strategic Plan in 2017 aimed at permanently reducing the

ship strikes of cetaceans in all the hotspots worldwide by 2020 (IWC, 2017).

3.3 Noise pollution The underwater noise emitted by human activities has been recognized as a potential threat to

cetaceans in the 1970s (Erbe, et al., 2018), when a study on baleen whales discovered that ship

noise actually affected their communication range (Payne & Webb, 1971). Since then, the issue

has become of major concern, with more recent standings being attributed to anthropogenic

sound exposure (Boyd, et al., 2008).

Noise produced by human activities can come from many different sources, including shipping,

pile driving for offshore construction, seismic exploration and a diversity of sonars for military

or civil purposes (Boyd, et al., 2008; Williams, et al., 2015; Middel & Verones, 2017).

Cetaceans have evolved to rely on sound for social communication and for acquiring information

from the environment (Boyd, et al., 2008). Therefore, noises interfering with this fine-tuned

communication can pose serious threats to their survival (Middel & Verones, 2017). For

instance, killer whales (Orcinus orca) have been shown to have different dialects that are

culturally transmitted within the same population (Ford, 1991); and other odontocetes are known

to use echolocation to travel, forage and communicate (Erbe, et al., 2018).

The highly developed auditory receptor system of cetaceans can be affected by anthropogenic

noise in ways that can have consequences at both the individual and population level (Boyd, et

al., 2008). For instance, effects can range from injury, temporary or permanent loss of hearing,

several behavioural responses that can interfere with fitness-related activities (e.g., foraging and

reproduction), masking and high stress levels (La Manna, et al., 2013; Williams, et al., 2015;

Erbe, et al., 2018). Although cetaceans have been observed to adopt strategies to avoid high

levels of disturbances such as leaving the area or changing their acoustic behaviour (La Manna,

et al., 2013), this is likely to have fitness consequences if certain activities are interrupted (e.g.,

foraging, resting or breeding) (Erbe, et al., 2018).

In the waters around Tenerife, most of the noise produced by human activities is likely to come

from boat traffic. Since still little is known about the amount of anthropogenic sound that is

actually emitted, future research is needed in this direction.

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4. Fieldwork Training

Training for both staff and volunteers is conducted by the Principal Investigator (PI), Project

Manager (PM) and the Assistant Research Officers (ARO). As the project relies on the

participation of volunteers with varying levels of scientific experience, it is vital that training is

detailed and systematic. Staff involvement in data management requires the provision of further

training in software such as Darwin and Excel. To ensure all volunteers and staff are trained to

an appropriate level to undergo fieldwork, all participants must pass both a species identification

and data collection test. Volunteers must receive a score of at least 80% or more to be permitted

to take part in data collection for this project.

Training Presenters Audience General Introduction PI/PM Staff/volunteers

Risk Assessment PI/PM Staff/volunteers

Cetaceans in

Tenerife

PI/ARO Staff/volunteers

Data Collection

Methods

PI/ARO Staff/volunteers

Mysteciti Whale

Identification

PI Staff/volunteers

Darwin Catalogue in

Tenerife

PI Staff

Table 1: Training and briefing sessions that were conducted during phase 194.

4.1 General Introduction Training begins first with a briefing session where a general introduction to Tenerife and the

context of the project is given. During the briefing session, volunteers are given an introductory

presentation on the Tenerife project. The presentation includes an introduction to Frontier and its

mission statement, aims and objectives, a brief introduction to the Canary Islands and Tenerife

itself, and activities/sites the volunteers can do or visit in their free time. The living conditions of

the house are explained, and the daily chores expected to be carried out by volunteers and staff

are highlighted and explained. Around the house important information is pointed out, including

the fire emergency plan, weekly schedules that are updated each week with general information

on day to day activities, such as start times. A brief description of the types of surveys carried out

during the project are given, but these are expanded on either later in the training, or whilst on

the surveys. By the end of the general introduction volunteers should be familiar with the way of

life on the project, and with what is expected from them both in the house and when representing

Frontier.

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4.2 Risk Assessment The risk assessment for the project is clear and important, and everyone, including staff and

volunteers, must follow them. Failure to do so may result in a verbal or written warning, or

possible termination from the project, depending on the severity of the offence. Volunteers go

through the risk assessment with the member of staff conducting their briefing session. For each

risk, a clear description is given, detailing what is and is not allowed. The consequence for not

following each risk is highlighted, so volunteers are clearly aware of what will happen if they are

found not abiding by the risk assessment. The risks range from potential problems in the house,

to problems that could arise when volunteers are on boats and/or representing Frontier.

Volunteers are also briefed on what to do if they happen to see another volunteer, or staff

member, not following the risk assessment. A copy of said risk assessment can be found in the

communal house and is pointed out to the volunteers upon their arrival.

4.3 Cetaceans in Tenerife Once the volunteers have been briefed on the general aspects of the project, they are introduced

to the 24 species found in the waters surrounding Tenerife and a few key features on how to

distinguish each species. The session starts with a general background to cetaceans, including

their evolution and the main differences between cetacean species and fish. The cetaceans as a

group are then split into the mysticetes and odontocetes, with the reasoning behind why the

group is split in two explained. The mysticete whales are firstly described, with each species’

key features emphasized. Visual aids of the different types of feeding techniques within the

group are shown via video, to highlight the features and different species. Similar techniques are

then used to go through the odontocete species found around Tenerife, again emphasizing the

key features of each species so the volunteers can identify them in the field. Lastly, the

volunteers are shown the four resident species to Tenerife; the sperm whale, Risso's dolphin,

short-finned pilot whale and bottlenose dolphin, with particular emphasis on how to identify the

short-finned pilot whale and bottlenose dolphin, as these two species are almost guaranteed to be

seen by the volunteers. The volunteers then participate in a short species identification quiz,

where photographs of different species are shown. At the end of the cetacean briefing session

volunteers should feel comfortable identifying the species found in Tenerife, and able to give a

brief description of each species, in particular the short-finned pilot whale and bottlenose

dolphin, in the event that they are asked to talk about them on the boats.

4.4 Data Collection Methods

Training for fieldwork is conducted during the briefing session, and then expanded on by a staff

member whilst in the field, either on the boats or at the coastal site. Volunteers are given a brief

description of the whale watching boats we are in partnership with: Eden, Shogun, Peter Pan and

Ragnarök, and an explanation of what is expected of them whilst on said boats in order to help

the crew. The data and identification photographs that the volunteers would have to collect

whilst on board the boats are explained, with particular focus on the standard of photographs

needed for the identification photos; clear, distinct dorsal fin photos, usually focused on one

individual and taken with the individual in close proximity to the boat. The volunteers are then

shown the datasheet used to collect the behavioural data of the cetaceans whilst on the boats ,

with the sections of the sheet explained, for example how to distinguish the different behavioural

responses cetaceans can demonstrate as a reaction to the boats, and whether these mean the

individuals are interacting, avoiding or having no response to the presence of the boat .

Volunteers are then given an example data sheet to enter into the project database, with a staff

12

member guiding them on how to enter the data correctly. Staff-members make sure the

volunteers are aware of how to correctly name the photographs, and which folders to put them in.

Although the matching of the photographs is then usually carried out by staff members on

DARWIN, a program which helps researchers identify individuals within a species, through the

matching of their fins (DARWIN2015), volunteers are made aware that if they would like to

participate in this activity then a staff member will go through the matching process.

As previously mentioned, the volunteers complete a test, needing a score of 80% or above to be

allowed to go on the whale watching boats. Fieldwork training then continues on their first boat,

with a staff member going through the data sheet again. The first interaction with a cetacean is

completed by both the staff member and the volunteer and, if the staff member feels that the

volunteer can correctly identify and fill out all the sections of the datasheet, the volunteer will

complete the subsequent interactions on their own.

4.5 Mysticeti Whale Identification Mysticeti species can be observed throughout the year in Tenerife, with sightings including the

fin whale (Balaenoptera physalus), Bryde’s whale (Balaenoptera brydei), sei whale

(Balaenoptera borealis), humpback whale (Megaptera novaeangliae), blue whale (Balaenoptera

musculus) and minke whale (Balaenoptera acutorostrata)(Carrillo, et al., 2010). Although

occurrence of mysticete cetaceans is not common, it is difficult to identify differences between

large cetaceans without sufficient training. During this phase, Bryde’s whales balaenoptera

edeni were sighted on several occasions during boat surveys. Therefore, a training presentation

was developed to help surveyors identify fine-scale differences in rorqual species through

watching videos of surfacing behaviours and examining photographs of the cetacean’s unique

differences. During this training session staff and volunteers were also encouraged to record

mysticetes as ‘unknown large cetacean’ when out in the field, unless they are certain in their

identification. They are also advised to take photographs and videos for later identification back

at the project base.

4.6 Darwin Catalogue in Tenerife A new training presentation was created for the purpose of training staff in the software Darwin.

Darwin is a fin ID software that allows traced fins to be stored in a catalogue for automatic

detection of individuals (Darwin, 2019). The presentation starts by introducing the potential

applications of fin ID studies in calculating abundance, tracking migration and assessing

community structure. The context of the objectives for Frontier’s fin ID project is provided

through a summary of relevant literature and previous studies on short-finned pilot whales and

bottlenose dolphins in Tenerife. Staff are then trained in how to enter/check fins in the catalogue;

with an emphasis on the correct tracing of fins, making sure photographed individuals are

swimming to the left. Factors that can obscure tracing such as glare or high contrast waves are

also discussed. Collaboration with the pre-existing La Laguna University catalogue and correct

naming of individuals is also covered during this session. By the end of the training, individuals

should feel confident that they can correctly input new fins and identify matches in the Darwin

catalogue. All training resources are available to attendees following the session for reference

whilst using the programme.

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5. General Project Information

5.1 Survey Area The location of the whale and dolphin conservation project is in the southwest of Tenerife,

Canary Islands, Spain, with the communal house located in the village of Oroteanda

(Guargacho). Boat fieldwork for the project is carried out on four partnership boats, Peter Pan

and Ragnarök leaving from Puerto de Los Cristianos (28:0489oN, 16:7116oW) and Shogun and

Eden leaving from Puerto Colon (28:0785N, 16:7355W).

Figure 2.1: A map displaying the location of the survey area within the Teno Rasca Special Area of Conservation

(SAC) in the channel between Tenerife and La Gomera (The European Environment Agency, 2019)

All boat trips take place in the channel between Tenerife and La Gomera in the Teno Rasca

Special Area of Conservation (Figure 2.1). From Los Cristianos Peter Pan runs a morning trip

from 10:00 – 13:00 and an afternoon trip between 13:30 – 15:30 and Ragnarök runs two trips,

the timings of the trips change depending on the day, for example on Wednesday’s the trips run

10:00 – 12:00, 12:30 – 15:30, and on Friday they run 12:30 – 15:30 and 16:00 – 18:00. From

Puerto Colon Shogun runs one five-hour trip each day, leaving at 11:00 and travelling to Los

Gigantes. Eden has three excursions a day, leaving at 11:00, 13:00 and 16:00. All four whale

watching boats used during the project fly the Barco Azul/Blue Boat ag, meaning the crew and

company agree to provide whale watching experiences that keep the welfare of the animals their

main priority.

The coastal surveys for the project were conducted on the cliffs of Los Cristianos (Figure 2.1;

28.0489oN, 16.7116oW), belonging to the Mountain of Guaza and overlooking the fish farms

which are regularly used for the common bottlenose dolphin as feeding grounds. Community

beach cleans are conducted on beaches along the south coast of Tenerife at four sites, including:

Los Cristianos, Las Americas, Las Galletas and El Medano.

14

Figure 2.2: Typical route taken by Eden (green route), Shogun (purple route) from Puerto de Colon, Peter Pan (red

route) and Ragnarok (blue route) from Los Cristianos using GPS data from boat survey data, 2018

5.2 General Aims The general aim of the conservation project in Tenerife is to establish a long-term cetacean

monitoring program, studying the abundance and distribution of cetaceans, habitat use of

different species, and the effect of boat encounters on behaviour and group composition. This is

to provide information to work towards ensuring the conservation of resident cetacean species

and migratory species in the waters surrounding Tenerife, with the large-scale aim of

establishing long-term management of the area and assisting in promoting marine conservation

in the wider region.

The general aims are achieved by following a set of objectives:

● To use boat-based surveys to collect abundance and behavioural data on cetaceans

surrounding the southwestern coast of Tenerife, focusing on their responses in relation to

boat presence and building a photo identification database of all resident individuals.

15

● To use a new method of land-based survey to monitor the behaviour of cetaceans around

fish farms in the southwest of Tenerife, focusing on their responses to boats and the

activity of the boats.

● To carry out regular beach cleans along the southwestern coast of Tenerife, removing any

waste and reducing the impact of humans to the coastal area, with the intent to start

categorising the waste to identify the main contributors.

6. Research Project

Behavioural Response and Fine-Scale Movement of South West Tenerife’s Cetaceans with

Vessel Traffic

6.1 Gaps in Knowledge The southwest of Tenerife is a year-round tourist destination, with millions of tourists

participating in whale watching (Aguilar, et al., 2001). Aside from whale watching, tourism

creates recreational boat traffic in the Teno Rasca SAC area through pleasure crafts, jet skis and

an increasing number of fast ferry routes (Ritter, 2010). A legally recognised code of conduct,

the ‘Barco Azul Blue Boat’ was announced in 1998 to minimise disturbance to cetacean species

by whale watching boats. The code encourages companies to keep distance around cetaceans and

limit the number of boats in the area (Patentes-y-marcas, 2019). However, despite regulations,

codes of conduct are often poorly enforced (Duprey, et al., 2008). Additionally, an unknown

number of boats interact with cetaceans on a daily basis without the Barco Azul Blue Boat

certification. According to the Barco Azul Code of Conduct, it is a compulsory rule that boats

must not concentrate around cetaceans, and no more than two boats should be present during an

encounter (WebTenerife, 2020). Frontier Tenerife’s previous scientific report identified that the

number of both legally certified and non-legally certified vessels interacting with cetaceans has

increased since 2017. Two or more legal boats were present for 47.5% of all cetacean

encounters, whilst 20.78% of encounters had illegal boats present (Davies, et al., 2019). This is

concerning given that an increased number of boats around cetaceans can lead to avoidance

behaviour, causing potential long-term fitness degradation (Williams & Ashe, 2007. Lusseau

&Bejder, 2007). Additionally, when boats interact illegally with cetaceans there could be greater

potential for disturbance. Those skippering the vessel may be inexperienced around cetaceans

and behave irresponsibly (Patentes-y-marcas, 2019).

There has been some evidence that whale watching causes short term disturbances in local

cetacean species; the bottlenose dolphin and short-finned pilot whale, where avoidance

behaviours have been frequently observed around boats (Aguilar, et al., 2001). However, there

are no present studies that have investigated whether boats following the code of conduct merit a

different behavioural response to those that do. This study aims to investigate whether an

increasing boat number and illegal boat presence impacts the short-term behavioural response of

cetaceans. This study will also incorporate calf presence into its investigation, as calves are

physiologically limited and are less able to dive or swim as quickly as an adult. It is therefore

possible that groups with calves may have an increased vulnerability to whale watching vessels

(Higham, 2014; Morete, et al., 2007). This study will also include the Atlantic spotted dolphin in

16

the analysis, due to the high number of observations of this species over the data collection

period.

Additionally, aquaculture, a recent development in Tenerife, promotes vessel traffic along the

coast from Los Cristianos (Citizen Services, 2019). Bottlenose dolphin sightings are often

concentrated around coastal fish farms in Tenerife, as the species is well known for the

exploitation of fish farms for foraging opportunities (Díaz López & Bernal Shirai, 2007).

Therefore, bottlenose dolphins at this site are vulnerable to disturbance from both recreational

boats looking to engage with the dolphins and the constant presence of fishing and fish farm

maintenance boats (Davies, et al., 2019). As the fish farms are located beneath a coastal vantage

point, these farms provided an opportunity to observe fine scale movements of dolphins in

relation to vessel traffic. This allows the assessment of whether the presence of cetaceans is

affected by specific boats and their behaviour. According to the code of conduct, boats should

not drive at a speed of more than 5-6 knots when within 300 metres of cetaceans (Tenerife whale

and dolphin watching, 2020). High speeds create greater potential for noise pollution, physical

disturbance and vessel collisions with cetaceans (Erbe, et al., 2018; Van Waerebeek, 2007). High

speed boats, including jet skis and motor boats, regularly interact with dolphins around fish

farms in Los Cristianos. Additionally, there is the constant presence of fishing and fish farm

boats. Bottlenose dolphins are especially susceptible to incidental capture from fishing vessels

(Díaz López & Bernal Shirai, 2007). The previous Frontier report identified bottlenose dolphins

possess a higher vulnerability to any effects from fishing boats and jet skis, given their spatial

overlap (Davies, et al., 2019). It is therefore vital to continue monitoring these vessels and their

interactions with bottlenose dolphins.

6.2 Aims/Objectives

1. The first aim of the phase 201 report was to investigate whether the behavioural response

of Globicephala macrorhynchus, Tursiops truncatus and Stenella frontalis varied

between species and with increasing boat numbers, illegal boats and calf presence.

2. The secondary aim was then to quantify the effect of specific boat factors on the presence

of cetaceans around fish farms in Los Cristianos.

These aims were achieved by the following objectives

Aim 1

● Combining boat-based observations of behavioural events to categorise specific vessel

encounters as either ‘no response’, ‘interaction’ or ‘avoidance’ per the number and type

of boats present.

● Using multiple-logistic regression to determine whether an increasing boat number,

illegal boat presence (where there is at least one illegal boat present) and calf presence

(where there is at least one calf present) impact the probability of behavioural responses

in each species.

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● Comparing the total percentage behavioural responses between the three species, to

assess for species specific sensitivity to vessel traffic.

Aim 2

● Using land-based observations of vessel traffic at the Los Cristianos fish farms to assign

one of 8 types to each boat (e.g. fish farm boat. jet ski etc) quantify boat movements

(stay, slow, mill, fast) and boat noise (low, medium, high) recorded within the marked

study area.

● Using land-based observations of cetacean movements around the Los Cristianos fish

farms to determine whether cetaceans were present or absent in the vicinity of vessel

traffic and then calculating cetacean presence (presence/total(n) for each boat factorial

condition.

● Applying a binomial logistic regression to investigate whether boat factors were

impacting the probability of cetacean presence.

6.3 Materials and Methods

6.31 Boat-Based Fieldwork

Boat fieldwork was carried out from December 2019 to March 2020 in the southwest of

Tenerife. During surveys 1 to 4 trained surveyors were present on board 1 of 4 legally certified

partner whale watching boats (Ragnarok, Shogun, Eden and Peter Pan). All four boats differ in

size, shape and material. Eden is a plastic catamaran, and the smallest of the 4 boats, capable of

holding a maximum of 50 people. Peter Pan is a boat reaching 18m, and is an authentic wooden

Portuguese schooner, capable of carrying a maximum of 60 people. Ragnarök is a wooden

Viking ship, also carrying a maximum of 60 people and Shogun is the largest of the 4 whale

watching boats, reaching 26m long, made of Teak hardwood and has a maximum capacity of 144

people. Using the four different boats gives different surveying experiences and may potentially

give different responses by the cetacean species.

Sea conditions were measured at the start of each survey included; Beaufort Sea State (0-5),

visibility (0-5, where 0 is poor and 5 is clear) and percentage cloud cover (0-10, where 0 is clear

and 10 is complete cloud cover). Encounters began when the boat was within 500 metres of an

individual/group. Animals were identified to the lowest taxonomic level possible, which for most

sightings was the species. Fin identification shots are also taken where possible of bottlenose

dolphins and short-finned pilot whales. The start time and end time of encounters were recorded

and GPS coordinates were taken using the Google Map application (Google Maps, 2019). Calves

were identified by their paler colouration and smaller size (Olson, 2009). To increase certainty in

the recordings, multiple observers took part in boat fieldwork.

18

Any additional boats that were present during encounters (within 500 metres of cetaceans) were

recorded. Behavioural events were recorded individually per the number and type of boats

present, allowing separate behavioural responses for changing vessel traffic conditions to be

identified during a single encounter. Boat number was defined as 1 (only the research vessel you

are on is present in the encounter), 2 (the research vessel and one other boat are present) or 3+

(there are more than 2 other boats present in an encounter). Boat numbers over 3 were grouped

together as 3+ due to the small sample sizes at greater than 3 boats. Boat type was defined as

legal, illegal, fishing boat or jet ski. Only legally certified whale watching boats are permitted to

fly the yellow and blue Barco Azul flag. Therefore, legal and illegal tourist boats were

distinguished from one another by the Barco Azul flag. Behavioural events were used to then

determine whether the overall response was ‘no response’, ‘avoidance’ or ‘interaction’ by the

following definitions.

Approach: Individuals actively approach the vessel (Interaction)

Scout: Individuals approach the vessel but instantly swim/dive away (Avoidance)

Bow-ride: Individuals swim parallel to the boat, in the waves created by the boat (Interaction)

Spy-hop: Individuals are vertical in the water with their heads up above sea level (No Response)

Belly-up: Individuals spin around and have their belly facing the sky (No Response)

Tail slap: Individuals slap the surface of the water with their flute (No Response)

Dive: Individuals deep dive, usually shown by a large exhalation before diving (Avoidance)

Surf: Individuals swim on the surface of the water, using the waves to move them forward (No

Response)

Breach: Individuals leap out of the water (No Response)

Change in group spacing: Individuals either come together or split apart (Avoidance)

Change in speed: Speeding up/ slowing down of individual (Avoidance)

Change in direction: Individual takes a definite change in the direction it was swimming

(Avoidance)

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If no behavioural events occur, then it is noted that the group had no response to the boat’s

presence.

6.32 Land-Based Fieldwork

Land-based fieldwork was carried out from December 2019 to March 2020. Observers were

stationed at an overlooking point above the fish farms of Los Cristianos. Fish farms were

categorised and divided into zones (appendix 3-4). Observers were divided into two teams,

where one focused on tracking cetaceans and the other on tracking boat movements. When boats

first entered the survey zone, they were classified into a boat type (fish farm, fishing, jet ski,

kayak, speed boat, tourist boat or yacht). When a boat changed position, its speed of movement

(stay, slow, mill, fast), along with the resultant noise (low, medium, high) were recorded.

Cetacean movements were tracked and recorded at 5-minute intervals to confirm whether

cetaceans were present/absent in the zone of an observed boat.

6.4 Data Analysis Data was first organized and processed using Microsoft Excel. All data analysis was carried out

in Rstudio (Rstudio team, 2015). The percentage presence of cetaceans for land-based data was

calculated using Excel pivot tables. Plots were produced using the R package ggplot2 (Wickham,

2016). Statistical analysis for both boat and land-based data was carried out in the R package

nnet (Venables & Ripley, 2002) As all data contained unordered categorical variables, logistic

regression was chosen for analysis; where a multinomial model was applied per species for the

boat data, whilst a binomial model was used for land-based data.

7. Results

7.1 Behavioural Responses

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Figure 3.1: Percentage response of Globicephala macrorhynchus in encounters from December 2019 until March

2020 (n=141) with a) the number of boats involved in the encounter b)the presence of illegal boats (where there is

more than one illegal boat present) and c) the presence of calves (where there is more than one calf present)

Encounters are categorised by behavioural events as no response (light grey), interaction (dark grey) or avoidance

(black) behaviour.

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Figure 3.2: Percentage response of Tursiops truncates in encounters from December 2019 until March 2020 (n=56)

with a) the number of boats involved in the encounter b)the presence of illegal boats (where there is more than one

illegal boat present) and c) the presence of calves (where there is more than one calf present) Encounters are

categorised by behavioural events as no response (light grey), interaction (dark grey) or avoidance (black)

behaviour.

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Figure 3.3: Percentage response of Stenella frontalis in encounters from December 2019 until March 2020 (n=51)

with a) the number of boats involved in the encounter b)the presence of illegal boats (where there is more than one

illegal boat present) and c) the presence of calves (where there is more than one calf present) Encounters are

categorised by behavioural events as no response (light grey), interaction (dark grey) or avoidance (black)

behaviour.

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Globicephala macrorhynchus

For short-finned pilot whales, there was no statistically significant effect of increasing boat

numbers (p>0.3 in all cases) on the probability of there being avoidance behaviour, or where

there were 1 or 2 boats present (p>0.1 in all cases) on the probability of there being an

‘interaction’ behavioural response. However, where there were more than 3 boats present (as

compared to there being one boat present), there was a 92% decline in the probability of

interactive behaviour, with a z value of -2.58 and an associated statistically significant p value of

0.009. Additionally, when illegal boats were present, there was a 92% increase in the probability

of interactive behaviour, with a z value of 2.52 and a p value of 0.01. There was no statistically

significant effect of illegal boat presence on avoidance behaviours (p= 0.2) These patterns are

reflected in the percentage of total observed behavioural responses in Figure 3.1 where

interactive behaviour notably decreases when they are more than 3 boats and increases when

illegal boats are present. From Figure 3.1 it additionally appears that when calves are present,

short-finned pilot whales generally become less responsive, showing a greater tendency for ‘no

response’. However, there was no significant change in the probability of there being an

interactive or avoidance behavioural response as a result of calf presence (p>0.3 in all cases).

Tursiops truncates

For bottlenose dolphins, there was no significant effects of increasing boat numbers (p>0.05 in

all cases), illegal boat presence (p>0.1 in all cases) or calf presence (p>0.8 in all cases) on the

probability of there being avoidance or interactive behaviour. From Figure 3.2 it appears that

despite statistical insignificance there are patterns arising, with a greater tendency for ‘no

response’ behaviours with increasing boat numbers, illegal boat presence and calf presence. As

the sample size for bottlenose dolphins (n=56) was relatively smaller than that for the short-

finned pilot whale (n=141), more data is needed to detect any patterns in behavioural responses.

Stenella frontalis

For Atlantic spotted dolphins, as there was only one instance where avoidance behaviour was

observed, avoidance data was not included in the statistical analysis. Boat number had an

insignificant effect on the probability of interactive behavioural responses across boat numbers

where there were 2 or 3 boats present (p>0.06 in all cases). However, when there was only one

boat present, the probability of interactive behaviours drastically increased (coefficient e =2.6e+01)

with a z value of 3.1 and an associated p value of 0.001. Figure 3.3 demonstrates a greater

tendency for ‘no response’ behaviours with increasing boat numbers, resulting in less interactive

behaviours. The model was unable to assess the effect of illegal boat presence due to a small

sample size where illegal boats were present. However, Figure 3.3 demonstrates how avoidance

behaviour and interactive behaviour appear to decline with illegal boat presence. Calf presence

was insignificant for the probability of observing an avoidance or interactive behavioural

response (p>0.7 in all cases). Although insignificant, Figure 3.3 demonstrates an increase in

avoidance behaviour when calves are present. Given the relatively small sample size of Atlantic-

spotted dolphin encounters (n=51), more data would be needed to confirm any behavioural

changes

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7.2. Species Specific Differences

Figure 4: Comparison of percentage response derived from total encounters from December 2019 until March 2020

for Globicephala macrorhynchus (n=141), Tursiops truncates (n=56) & Stenella frontalis (n=51). Encounters are

categorised by behavioural events as no response (light grey), interaction (dark grey) or avoidance (black)

behaviour.

Figure 4 compares the overall behavioural responses to all encounters between short-finned pilot

whales, bottlenose dolphins and Atlantic spotted dolphins. Short-finned pilot whales showed the

highest relative amount of avoidance behaviour, followed by bottlenose dolphins. Avoidance

behaviour was only present in 1 out of 51 encounters with Atlantic spotted dolphins. Atlantic

spotted dolphins showed the highest tendency to interact with vessels, whilst interactive

behaviour was lowest in short-finned pilot whales. Bottlenose dolphins showed little preference

towards any single behaviour responses over all encounters; no response (32.1%), interaction

(39.2%), avoidance (28.6%). Meanwhile, short-finned pilot whales showed a preference towards

no response (41.8%) or avoidance behaviour (44%), as opposed to interactions (14.2%). Atlantic

spotted dolphins demonstrated highly interactive behaviour, with interactive behaviour observed

in 84.3% of all encounters, whilst no response (13.8%) and avoidance behaviour (2%) were

almost negligible.

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7.3 Cetacean Presence with Vessel Traffic Around Fish Farm

Figure 5 Percentage presence of Tursiops truncates in relation to boat factors a) boat type, b) boat movement and c)

boat noise during land-based surveys from January 2019 until December 2019 (n=1769). Percentages are derived

from cetacean presence/total(n) for each boat factorial condition.

Figure 5 demonstrates the percentage presence of bottlenose dolphins around the Los Cristianos

fish farms over varying boat types, movements and noises. From Figure 5, it can be seen that

cetaceans are most present around kayaks (27.2%) fish farm boats (24.7%) and least present

26

around jet skis (4.4%) and yachts (6%). However, in the binomial logistic regression model

when all boat factors are considered, fish farm boats actually cause a 55% decline in the

probability of cetacean presence with a z value of -5.6 and an associated p value of 2.46e-08.

Additionally, yachts (when compared to fish farm boats) cause a 75% decline in the probability

of cetacean presence with a z value of -2.2 and a p value of 0.03. All other boat types, when

compared to fish farm boats, had insignificant effects (p>0.08 in all cases).

From Figure 5 it appears that both species of dolphin are most present when boats are stationary

(30.5%) and least present when boats are moving fast (7.5%). From the logistic regression, there

was a decline of 40% in the probability of cetacean presence when boat movement increased

from stationary to moving slowly where the t value was -2.5 and the p value was 0.03.

Additionally, when fast boat movements were compared to stationary boat movements, there was

a 76% decline in cetacean presence where the z value was -4.3 and the p value was 1.94e-05.

Figure 5 demonstrates that the highest percentage of cetaceans occurred at low boat noise

(24.5%) whilst the lowest occurred at a high boat noise (8%). However, boat noise did not have a

statistically significant effect, when compared against a ‘low’ boat noise, for both medium and

high boat noises (p>0.7 in all cases).

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8. Discussion

8.1 Behavioural Responses

For each species there were varying behavioural responses when boat numbers increased (Figure

3). Short-finned pilot whales demonstrated a decrease in interactive behaviour when there were

more than 3 boats present (Figure 3.1) and Atlantic spotted dolphins showed an increase in

interactive behaviour when there was only one boat in an encounter (Figure 3.3). These results

suggest Tenerife’s cetaceans are more likely to interact with a solitary whale-watching vessel

than several boats. Both bottlenose dolphins and Atlantic spotted dolphins also show a general

trend towards non responsive behaviours when boat numbers increase. These results could be

interpreted in a number of ways. William and Ashe (2007) identified that killer whales

successfully evade whale-watching boats in low numbers, but become non-responsive when

overcrowded. They hypothesise that avoidance is not a viable option when traffic becomes

saturated, causing killer whales to become despondent (Williams & Ashe, 2007). It could be that

declining interactive behaviour with boat number reflects a stress state that is harder to detect

from behavioural observations alone. Stress hormones and catecholamines can be successfully

used to indicate physiological signs of stress in cetacean species and may be useful in future

work for supplementing behavioural data (Fair, et al., 2014). However, despite a decrease in

interactive behaviour, individuals did not show any notable increase in avoidance with vessel

traffic. Several studies have successfully detected avoidance behaviour towards vessels using the

same behavioural events as in this research project; e.g. direction changes (Beijder, et al., 2006;

Mattson, et al., 2005), speed changes (Matsuda, et al., 2011), group spacing changes (Do Valle,

Cunha Melo 1953; Aguilar, et al., 2001) and dives (Hastie, et al., 2003). Therefore, the absence

of avoidance behaviour with increasing boat numbers could indicate a process of habituation in

Tenerife towards vessel traffic. However, more long-term data is needed before any such

inferences can be made.

The presence of illegal boats only proved statistically significant in the case of short-finned pilot

whales (Figure 3.1), where interactive behaviour actually increased. For bottlenose dolphins and

Atlantic spotted dolphins there was a greater tendency for non-responsive behaviour (Figure 3.2-

3.3). These results, although preliminary, raise questions about the code of conduct and its

enforcement in Tenerife. It has been previously identified that legalisation is ineffective in

preventing avoidance behaviour; with bottlenose dolphins in a New Zealand population being

more negatively impacted by whale-watching vessels with certification than those without

(Constantine, et al., 2003). As short-finned pilot whales appear more interactive around illegal

boats, this could indicate that a code of conduct does not explicitly mean cetaceans will be more

open to whale-watching vessels. However, the increase in interactive behaviour around illegal

boats could alternatively be as a result of these boats gaining closer distances and ‘chasing’

cetaceans, ignoring the conditions of the code of conduct (Tenerife whale and dolphin watching,

2020). It is questionable how closely many legally certified boats comply with regulations

(Duprey, et al., 2008). If both legally and illegally certified boats behave similarly, it is unlikely

that legal boats will evoke more positive cetacean responses. However, it may be difficult to

determine specific effects of different vessels on short-term cetacean behaviour when Tenerife’s

cetaceans are exposed constantly to both legal and illegal boats. The results may be influenced

by prior encounters outside of survey hours (Aguilar, et al., 2001). More regulation is needed in

Tenerife to ensure the standards of the code of conduct are being upheld.

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The previous science report identified that calf numbers in targeted whale-watching species were

either increasing or stable (Davies, et al., 2019). Groups with calves displayed no significant

difference in their behavioural responses for all three species (Figure 3). This could suggest

habituation towards whale-watching vessels, of mother and calf pairs, as opposed to direct

avoidance (Watkins, 1986). For example, humpback whale mother and calf pairs have

demonstrated clear avoidance towards boats in Brazil (Morete, et al., 2007), whilst Atlantic

spotted dolphins increased in sightings from boats over time in La Gomera (Ritter, 2003). As

Tenerife is thought to be an important calving ground for both short-finned pilot whales and

bottlenose dolphins, groups with calves may have acclimatized to vessel traffic (Carrillo, et al.,

2010).

8.2 Species Specific Differences Cetaceans are believed to have species specific sensitives towards boat traffic, with those with

more sociable characteristics being more likely to habituate (Ritter, 2003). Atlantic spotted

dolphins were identified as the most interactive species in this study, interacting in 84.3% of all

encounters (Figure 4) and showing almost no avoidance behaviour. This aligns with other studies

that have found Atlantic spotted dolphins to be more open to vessel encounters (Ritter, 2003).

However, short-finned pilot whales showed dominantly avoidance or no response behaviour

(Figure 5). It could be that short-finned pilot whales have a higher sensitivity towards vessel

traffic. This could result in the disruption of important biological functions such as resting,

feeding or breeding for this species (Parsons, 2012). The code of conduct in Tenerife appears to

provide equal protection measures towards all cetacean species (Tenerife whale and dolphin

watching, 2020). However, this study highlights that some species, such as the short-finned pilot

whale may require extra regulations in place to prevent disturbance (Figure 5).

8.3 Cetacean Presence with Vessel Traffic Around Fish Farms The results of this study indicate that both fish farms and yachts cause a significant decline in the

probability of cetaceans being present (Figure 5). Fish farm boats are stationed almost

permanently at the fish farms, where they maintain the structure of the aquaculture pens. It could

be that given their constant presence, bottlenose dolphins have learnt to avoid them whilst

foraging at fish farms. Dolphins can have negative effects on the aquaculture industry, causing

the enclosed fish stress and directly harvesting fish from pens (Stickney & McVey, 2002). It

could be that conflicts exist between the maintenance boats and the dolphin population, causing

the bottlenose dolphins to distribute themselves away from fish farm boats when possible.

Yachts were additionally observed to cause a 75% decline in the probability of cetacean

presence. The yachts present around fish farms are not certified by the Barco Azul Blue Boat to

legally interact with cetaceans (Patentes-y-marcas, 2019). Therefore, they may behave

irresponsibly, inducing the absence of bottlenose dolphins around yachts at the fish farms.

The speed of the boat had a significant effect on the presence or absence of bottlenose dolphins.

There was a 76% decline in cetacean presence when boats were moving fast, compared to when

they were stationary. Other studies in Tenerife have identified that the speed of approach induces

avoidance behaviour (Aguilar, et al., 2001). Bottlenose dolphins at the fish farms may have

learnt to actively avoid fast moving vessels. The noise of the boat had no statistically significant

29

effect on cetacean presence, however cetaceans were 24.5% present when boat noise was low

and only 8% present when boat noise was high. This study was limited in its ability to detect

vessel noise, as it could only judge vessel noise above the water. Given that noise is known to

have a detrimental effect on cetacean populations, it would be useful to further investigate the

specific impact of noise pollution on bottlenose dolphins at the fish farms (Boyd, et al., 2008).

9. Conclusions/ Further Work

According to the Barco Azul Code of Conduct, no more than two boats should be present at one

time during a cetacean encounter (Tenerife whale and dolphin watching, 2020). This report

identified that interactive behaviour decreased for both short-finned pilot whales and Atlantic

spotted dolphins as boat numbers increased. There is therefore evidence that this specific

regulation should be respected and boat traffic should be reduced around cetaceans. However, as

the previous report (Davies, et al., 2019) identified boat numbers around cetaceans during

encounters are increasing over time, and whale watching policy in Tenerife is rarely formally

enforced, future work should further investigate the potential costs of overcrowding cetaceans.

Illegal boats did not cause an observably more negative behavioural effect than those certified by

the Barco Azul. Code of conducts are only effective when they are followed and enforced.

Whilst analysing specific boat factors during land-based observation, it appeared that the speed

of boats had a significant effect on whether cetaceans were present. Future work should therefore

include examining the behaviour of both legal and illegal boats with respect to cetacean

response, e.g. the speed of approach, direction of approach, time spent around the cetaceans and

distance of approach. There is also a lack of clarity in southwest Tenerife on the impact of the

Barco Azul Blue Boat certification on the whale-watching community. There seems to be a

disparity between the requirements for certification and the observed behaviour of the crew. This

is due to a lack of enforcement and monitoring of the area. It would therefore be beneficial if

boat crews could participate in a stakeholder survey to provide qualitative data to shed light on

this issue.

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11. Appendices Appendix 1: Boat data collection sheet

Encounter 1 2 3 4 5

Time

Start

End

GPS

28oN

-16oW

Species

Behavioural

State

Total

38

Composition

Males

Adults

Juveniles

Calves

Boats

Number

Illegal

Legal

Fishing

Jet Skis

Behavioural events

Approach

Scout

Bow-Ride

Spy-Hop

Belly-Up

Tail Slap

Dive

Surf

Breach

Speed Change

Direction Change

Group Spacing Change

Boat response

Behavioural

State A

Method

Notes

Appendix 2: Definitions of the different sections on the boat data sheets

Behavioural states

• Resting - Not actively swimming, ’bobbing’ around the surface of the water.

• Travelling - Swimming forward in one direction.

• Feeding - Shown by seagulls diving into the water where cetaceans are.

• Milling - Individuals are swimming within the same area but in all directions.

• Socialising - Cetaceans are interacting with one-another.

39

Behavioural events

• Approach - Individuals actively approach the vessel you are on (Interaction).

• Scout - Individuals approach the vessel you are on but instantly swim/dive away (Avoidance).

• Bow-ride - Individuals swim parallel to the boat, in the waves created by the boat (Interaction).

• Approach - Individuals actively approach the vessel you are on (Interaction).

• Scout - Individuals approach the vessel you are on but instantly swim/dive away (Avoidance).

• Spy-hop - Individuals are vertical in the water with their heads up out of the surface.

• Belly-up - Individuals spin around and have their belly facing the sky.

• Tail slap - Individuals slap the surface of the water with their fluke.

• Dive - Individuals deep dive, usually shown by a large exhalation before diving (Avoidance).

• Surf - Individuals swim on the surface of the water, almost as if gliding on the surface.

• Breach - Individuals leap out of the water (The whole body of dolphins leaves the water).

• Spy-hop- Individuals are vertical in the water with their heads up out of the surface.

• Change in group spacing- Individuals either come together or split apart.

• Change in speed- Speeding up/ slowing down of individual

• Change in direction- Individual takes a definite change in the direction it was swimming

Boats

• Illegal - Any boat that does not fly a Blue Boat flag (except for jetskis and fishing boats).

• Legal - Any boat which flies the Blue Boat flag.

• Fishing - Boats with obvious fishing poles/nets.

• Jet skis - Don’t count individual jet skis, count each group of jet skis as one.

Boat Number

• 1- 1 boat present (the boat you are on)

• 2 - 2 boats present (1 boat extra)

• 3 - 3 boats present (2 boats extra)

• 4 - 4 boats present (3 boats extra)

• 5 - 5 boats or more present (4 or more boats extra)

Method

40

• Search - Came across the pod whilst sailing.

• Radio - Captain heard about the pod through radio.

• Boat - Noticed the pod due to other boats being around.

Boat Response

• No response - Individuals showed no reaction to your boat being there.

• Interaction - Individuals showed interest in your boat.

• Avoidance - Individuals performed behaviours of avoidance (Scout, Dive, change in speed,

change in group spacing, change in direction)

Appendix 3: Land-based survey boat tracking form

LAND-BASED BOAT RECORDING FORM (Boat 1/1)

Date: __________ Start time:___________ End time:___________

Boat survey- make a new record for each new boat seen

Time

First seen Last seen

Boat

sighting

no.

Boat

type

Boat

movement

Boat

direction

Boat

noise

Zone/fis

h farm

Cetaceans?

(Y/N)

Cetacean

sighting no.

41

Appendix 4: Land-based survey cetacean tracking form

LAND-BASED SIGHTINGS RECORDING FORM - TIMED

INTERVALS

Dolphin (2/2)

Date: __________ Start time:___________ End time:___________

Timed intervals: make a new record of animals position every 5 minutes

Sighting

no.

Time Zone/fish

farm

Boat

response

Boat sighting

no.

42