Biodiversity Data Journal : Data Paper (Biosciences)
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Data Paper (Biosciences)
MONICET: The Azores whale watching contribution to cetacean monitoring
expand article infoLaura González García‡, Marc Fernández§, José M. N. Azevedo‡
‡ Institute of Marine Sciences - OKEANOS, University of the Azores, Rua Professor Doutor Frederico Machado 4, 9901-862, Horta, Portugal
§ MARE – Marine and Environmental Sciences Centre/ARNET - Aquatic Research Network, Agência Regional para o Desenvolvimento da Investigação Tecnologia e Inovação (ARDITI), Funchal, Portugal
Corresponding author: Laura González García (laura.gonzalez@uac.pt)
Academic editor: Paulo Borges
Received: 25 May 2023 | Accepted: 07 Jul 2023 | Published: 08 Aug 2023
© 2023 Laura González García, Marc Fernández, José Azevedo
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation: González García L, Fernández M, Azevedo JMN (2023) MONICET: The Azores whale watching contribution to cetacean monitoring. Biodiversity Data Journal 11: e106991. https://doi.org/10.3897/BDJ.11.e106991
 Open Access

Abstract

Background

The Azores islands have been historically linked to cetaceans, becoming an example of a successful transition from whaling to whale watching. Twenty-eight cetacean species have been sighted in these waters, making the archipelago one of the most recognised whale and dolphin watching destinations worldwide. The business is well-established in the region, operates in four of the nine islands year-round or seasonally and provides an excellent opportunity to collect long term information on cetacean distribution and abundance in an affordable way. Continuous monitoring is indeed essential to establish baseline knowledge and to evaluate cetacean response to potential natural or anthropogenic impacts. Opportunistic data greatly complement traditional dedicated surveys, providing additional support for appropriate management plans.

New information

The MONICET platform has been running continuously since 2009 as a collaborative instrument to collect, store, organise and disseminate cetacean data voluntarily collected by whale watching companies in the Azores. In the period covered by this dataset (2009-2020), 11 whale watching companies have voluntarily provided data from the four islands of the archipelago where whale watching takes place. The dataset contains more than 37,000 sightings of 25 species (22 cetaceans and three turtles). This manuscript presents the first long-term whale watching cetacean occurrence dataset openly available for the Azores. We explain the methodology used for data collection and address the potential biases and limitations inherent to the opportunistic nature of the dataset to maximise its usability by external users.

Keywords

citizen science, long term data series, opportunistic data, marine mammals, turtles

Introduction

Collecting long-term wildlife ecological data is challenging, especially for highly mobile species such as cetaceans which, in addition, inhabit remote regions like the high seas (Redfern et al. 2006, Fernandez et al. 2022). Cetaceans are considered ocean sentinels, in the sense that information about their ecology and distribution (e.g. changes in the phenology of migrations, shifts, expansions or reductions of their distribution ranges or changes in relative abundance over time) can be linked with the health of marine ecosystems (Moore 2008). Now more than ever, long-term ecological data are needed to address major issues of current environmental concern whose temporal scales span over decades and have global impacts. In fact, the impacts of global warming, pollution or overexploitation can only be adequately addressed in the long term (Jones and Driscoll 2022). For these reasons, EU Member States are required by the Marine Strategy Framework Directive (Directive 2008/56/CE) to monitor the status of their marine biodiversity in order to ensure a Good Environmental Status. However, dedicated cetacean surveys do not address these needs because, although they provide high-quality information, it is limited in both space and time by the complex and expensive logistics involved (Evans and Hammond 2004). In this context, commercial activities and citizen science have emerged as new opportunities for data collection, providing cost-effective access to long-term information that otherwise would be unavailable (Devictor et al. 2010, Theobald et al. 2015, Brown and Williams 2019).

The flagship status and charismatic nature of whales and dolphins have been widely recognised, making them ideal for maintaining the engagement of citizens in science and conservation. The attraction of these species has been demonstrated by the worldwide increase in whale watching over the last decades. The rapid expansion of this business has provided an educational tool for the public and an excellent opportunity for science (Dickinson et al. 2012, Higham et al. 2014, Currie et al. 2018a). In fact, whale-watching vessels have become opportunistic platforms of observation for citizen-science programmes, collecting data over long periods on a specific area. This results in a cost-effective survey method that allows the collection of precious cetacean information, which would likely be inaccessible without this collaboration and complements traditional surveys, particularly in areas with no baseline information or where funding is limited or not available (Currie et al. 2018a, Fernandez et al. 2018, Callaghan et al. 2021). Several monitoring programmes from opportunistic platforms have proven effective for cetacean data collection at sea, such as ferry or cargo routes or regular touristic trips. Successful examples include the ORCA Survey Network off the UK or the Fixed Line Transect Mediterranean monitoring Network working from European Atlantic and Mediterranean ferries, respectively (Kiszka et al. 2007, Arcangeli et al. 2012, Tepsich et al. 2020); the CETUS project, monitoring from cargo boats from Macaronesia and mainland Portugal (Correia et al. 2019); or the Kakila database, compiled from different whale watching sources in the West Indies (Coché et al. 2021). Opportunistic data obtained from whale watching have been used in multiple scientific publications to address, for example, cetacean distribution (Vinding et al. 2015, Alves et al. 2018), habitat preferences (Moura et al. 2012, González García et al. 2018, Fernandez et al. 2021, González García et al. 2022b) or animal movements (Currie et al. 2018b, Mullin et al. 2022).

The mid-Atlantic archipelago of the Azores has been linked to cetaceans since its colonisation in the 15th century. The first evidence of interaction refers to locals benefitting from stranded carcasses or animals found dead at sea (Azevedo 1991). In the mid-18th century, north American whalers arrived on the islands looking for new whaling grounds for sperm whales (Physeter macrocephalus) (see review in Prieto et al. (2013)). Initially, Azoreans were recruited as crew; and soon, the American whaling technique was adapted to a shore-based industry that expanded through all the islands. Land observers were responsible for finding the whales and guiding small open boats to them. Sperm whales were hunted primarily because of their oil, which was progressively replaced by other products making hunting less profitable (Ellis 2009). Thus, whaling gradually decreased from the 1960s onwards and it was officially banned in 1986 when the Moratorium of the International Whaling Commission ratified by Portugal in 1982 came into force. The last two sperm whales were hunted on Pico Island in 1987 setting the end of the whaling era in the Azores (Santos et al. 1995). Undoubtedly, whaling represented the first source of information about cetaceans in the Azores. Data obtained shed light on the distribution of sperm whales in space and time, their physical description and even their diet including deep-sea giant cephalopods (Clarke 1954, Clarke 1956, Clarke 1981). In 1987, the International Fund for Animal Welfare (IFAW), invited by the Azores Government and supported by the European Community, conducted feasibility studies to investigate the potential for whale watching in the Azores (Neves-Graça 2004). In 1989, the first activities started on Pico Island and they soon became a great attraction for tourists. Some of the lookouts working for the whalers joined the new business immediately, followed by some whalers as skippers, bringing their expertise and traditional ecological knowledge to a newer public (Neves-Graça 2006). In 1993, it was also established in São Miguel and, since then, whale watching has progressively extended to four of the archipelago's nine islands. Nowadays, 28 species of cetaceans have been listed around these islands (Silva et al. 2014, Azevedo and Barreiros 2019), making them one of the most recognised whale and dolphin watching destinations worldwide. In the Azores, this touristic activity mostly grew under an eco-tourism approach and, from the beginning, its regulation involved all stakeholders, including the government and the scientific community. In October 1998, the first “Bienal das Baleias”, held in Lajes do Pico, was a stage open for discussion, learning and training from multidisciplinary perspectives, looking for an “ecologically friendly” whale watching model (Neves-Graça 2004). As a consequence, the first whale watching legislation was published the following year (DLR 9/99/A) including an obligation to collect data on cetaceans sighted during the activity. This mandatory system proved ineffective and was soon abandoned, but it left a vacuum felt by all the parties involved: operators needed information to better plan a growing business and assess its sustainability, the government needed to monitor cetaceans to establish appropriate regulations and management plans and scientists saw the value of data collected cost-effectively, regularly and in the long-term. Discussions held during the last “Bienal das Baleias” in 2006, led to the development of the MONICET project: a consortium of a research centre and three whale watching companies, with economic support from the Azores Government, to establish a methodology to collect scientifically useful and reliable data compatible with the commercial operation and a database system to store, organise and disseminate the data on an open access basis.

General description

Purpose: 

We present the MONICET dataset of cetacean occurrences, based on opportunistic data collected by whale watching companies in the Azores. This dataset has already been published via GBIF, OBIS and EMODNET as a Darwin Core Archive. We aim to: (1) provide a detailed description of the methodology used for data collection; (2) acknowledge the limitations and potential sources of bias inherent to this dataset and (3) advise about the potential use of the data to minimise misinterpretation and maximise usability by external users.

Project description

Title: 

MONICET- the whale watching companies and the public at the service of knowledge and conservation of the Azores cetaceans

Personnel: 

Project coordination was done by José M. N. Azevedo, Marc Fernández and Laura González García. Data presented here have been collected by people working for 11 of the 23 registered whale watching companies: Azores Experiences and Peter Whale Watch in Faial Island; Aqua Açores and Espaço Talassa in Pico Island; Futurismo Azores Adventures, Picos de Aventura, Terra Azul, Terra do Pico and Sea Colors in São Miguel Island and Atlantiangra, Ocean Emotion and Picos de Aventura in Terceira Island. Company participation is voluntary; MONICET is permanently open to receive data from any company.

Study area description: 

The Azores Islands are located in the North Atlantic Ocean at 36-41° N and 24-32° W. The archipelago is composed of nine volcanic islands organised into three groups separated by deep waters (> 2000 m): the Western (Flores and Corvo), Central (Faial, Pico, Graciosa and Terceira) and Eastern groups (São Miguel and Santa Maria) (Fig. 1). The archipelago presents a well-defined oceanographic seasonality: March is usually the coldest month (SST ~ 15°C), while the highest temperatures are generally reached in September (SST ~ 25°C) (González García et al. 2022b). The spring bloom is noticeable each year by the increase in chlorophyll concentrations, which drastically drop to oligotrophic conditions during summer. The Azores are in a strategic location in the Mid-Atlantic, being affected by dynamic oceanographic features derived from the North Atlantic Current and the Azores Front/Current System, which enhance the primary production and the aggregation of life around these oceanic islands in comparison with surrounding waters (Caldeira and Reis 2017).

Figure 1.  

The Azores Archipelago, with the locations (white dots) of all the sightings recorded between 2009 and 2020 in the MONICET database. Base ports of contributing companies are indicated by black triangles.

Design description: 

MONICET is a collaborative platform to collect, organise and disseminate cetacean occurrence data and photo-identification images collected by whale watching companies in the Azores. Data are collected using a methodology developed collaboratively to provide scientifically useful information while remaining compatible with the commercial activity. An online database stores the data and a dedicated website (http://www.monicet.net/) provides a public interface to access basic geographical and statistical information. The project relies on the voluntary collaboration of the partners, mostly the whale watching companies and their staff, with the assumption that validated data will be openly shared and disseminated.

Funding: 

MONICET received a starting grant in 2008 from the Azores Government (M5.2.2/I/ 005/2008, 'MONICET - As empresas e o público ao serviço do conhecimento e conservação dos cetáceos dos Açores'). Since then, its running costs have been supported by the University of the Azores and its research centres. It is currently hosted by the Institute of Marine Sciences - OKEANOS, financed through the FCT – Foundation for Science and Technology, I.P., under the project UIDB/05634/2020 and UIDP/05634/2020 and through the Regional Government of the Azores through the project M1.1.A/FUNC.UI&D/003/2021-2024. It was hosted until February 2023 by the Azorean Biodiversity Group, affiliated with the Centre for Ecology, Evolution and Environmental Changes (UID/BIA/00329/2020-2023 - Thematic Line 1 "Integrated Ecological Assessment of Environmental Change on Biodiversity; and PO Azores Project - M1.1.A/FUNC.UI&D/010/2021-2024). An ongoing grant from the PO Açores 2020 Programme (AÇORES 01-0145-FEDER-000079, 'MEEMO - Maintain, expand and exploit the cetacean observation platform MONICET. A unique opportunity for science, public policy and business') is dedicated to modernising the computer infrastructure and exploring the scientific value of the data. Additionally, over the years, many students financed by EU Programmes ERASMUS and EURODYSSÉE participated in data collection, digitalisation and validation.

Sampling methods

Description: 

Data were collected in the Azores Archipelago (Fig. 1) by whale watching operators located in the four islands where whale watching takes place: Faial, Pico, São Miguel and Terceira. The project started with three companies in São Miguel and reached a maximum of nine companies providing data simultaneously in 2019 (Table 1).

Table 1.
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Whale watching companies reporting data to MONICET per year.

Island

Company

2009

2010

2011

2012

2013

2014

2015

2016

2017

2018

2019

2020

Faial

Azores Experiences

X

X

X

X

X

X

X

X

X

X

Peter Whale Watch

X

Pico

Aqua Açores

X

X

X

X

Espaço Talassa

X

X

São Miguel

Futurismo Azores Adventure

X

X

Picos de Aventura

X

X

X

X

X

X

X

X

X

X

X

X

Sea Colors

X

X

X

X

X

Terra Azul

X

X

X

X

X

X

X

X

X

X

X

X

Terra do Pico

X

X

Terceira

Atlantiangra

X

Ocean Emotion

X

X

X

Picos de Aventura

X

X

X
Sampling description: 

Cetacean occurrence data were collected from January 2009 to December 2020 by whale watching companies running tours from the islands of Faial (Horta harbour), Pico (harbours of Lajes do Pico and Madalena), São Miguel (harbours of Ponta Delgada and Vila Franca do Campo) and Terceira (Angra do Heroismo harbour). Generally, whale watching tours last between 2.5 to 3 h and are conducted twice a day: one in the morning (9:00 h approx.) and the other in the afternoon (13:30 h approx.), with an exceptional third trip in the high season. In São Miguel, the activity operates year-round, while in the other islands, it is more seasonal, operating primarily between May and September.

On all the islands, cetaceans are first located from land by experienced observers working with powerful binoculars from strategic locations on the coast. Whale watching boats are then guided from land to the location of the cetaceans. Therefore, each trip often presents one or more sighting events, where boats normally slow down or stop for clients to watch the animals.

For the database presented here, qualified and trained guides on board (often biologists) register the data manually at sea and type the information into the online database once on land. The time of departure and arrival of the boat to the base port is noted. Once with the animals, time, location (read from a GPS receiver) and species are recorded as a minimum. In most cases, a location is registered when the boat arrives near the animals and another when it leaves. Occasionally, intermediate points are also recorded. If the boat does not stop, just one location is noted for that observation. Additionally, number of individuals, presence of different life stages (adults, juveniles or calves), behavioural state and association with other species could be recorded, as well as sea state and visibility.

Quality control: 

The MONICET team provides annual training focused on data collection to the whale watching partners involved in the project. During these sessions, the desired data fields to be collected are extensively addressed and doubts about data collection are solved. The highly qualified profile of the guides or biologists of the companies, who are experienced and knowledgeable about cetaceans, is a reasonable guarantee of a correct species identification at sea.

Finally, information introduced in the online database is validated by a central team composed of researchers and trained interns. The validation process is mainly focused on mismatches in locations and timings and addresses any issues raised by the person entering the data. A dialogue is established, if necessary, until all the information is validated or the record is erased.

Step description: 

The data have been published following the standardised format for biodiversity data of Darwin Core Archive (DwC-A). This model consists of a core data file (eventTable) that contains information about the location and time of the sampling events (the encounters), associated through common database keys (i.e. eventID), with two extension data tables: the occurrenceTable, which contains taxonomical information about each sighting and the Extended Measurement Or Fact eMoFTable, containing biological and environmental measurements.

A hierarchical system was considered where each whale watching trip is a parent event and each encounter belonging to that trip is an event. On each event, several occurrences may happen, considering an occurrence the sighting of a life stage of a species. For instance, a group of individuals may be recorded as an occurrence or separate occurrences can be recorded for each life stage (adult, juvenile, calf). Additionally, the sea state and the visibility, as well as the behaviour, the number of individuals sighted, the life stage and the sampling instrument name are related to the corresponding occurrences.

Geographic coverage

Description: 

Azores Archipelago, Portugal

Coordinates: 

37.3118 and 39.908 Latitude; -25.008 and -28.9984 Longitude.

Taxonomic coverage

Description: 

Sightings were identified, whenever possible, to the species level. Otherwise, at least family was noted. Turtles were occasionally registered, although they were not the project's main goal. The dataset contains sightings of 22 species of cetaceans and three species of marine turtles (Table 2).

Table 2.
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List of taxa recorded on the MONICET platform between 2009 and 2020. Higher-level classification follows the World Register of Marine Species (WoRMS Editorial Board 2023); IUCN global conservation status according to IUCN (2022); AphiaID is the unique and stable identifier associated with each taxon in the WoRMS database through the use of Life Science Identifiers (LSIDs).

Class

Order

Family

Scientific name

Common name

 IUCN status

AphiaID

Mammalia

Cetartiodactyla

Balaenopteridae

Balaenopteridae n.i.

rorqual

136979

Mammalia

Cetartiodactyla

Balaenopteridae

Balaenoptera acutorostrata

minke whale

 LC

137087

Mammalia

Cetartiodactyla

Balaenopteridae

Balaenoptera borealis

sei whale

 EN

137088

Mammalia

Cetartiodactyla

Balaenopteridae

Balaenoptera edeni

Bryde's whale

 LC

137089

Mammalia

Cetartiodactyla

Balaenopteridae

Balaenoptera musculus

blue whale

 EN

137090

Mammalia

Cetartiodactyla

Balaenopteridae

Balaenoptera physalus

fin whale

 VU

137091

Mammalia

Cetartiodactyla

Balaenopteridae

Megaptera novaeangliae

humpback whale

 LC

137092

Mammalia

Cetartiodactyla

Delphinidae

Delphinidae n.i.

dolphins

136980

Mammalia

Cetartiodactyla

Delphinidae

Delphinus delphis

common dolphin

 LC

137094

Mammalia

Cetartiodactyla

Delphinidae

Globicephala macrorhynchus

short-finned pilot whale

 LC

137096

Mammalia

Cetartiodactyla

Delphinidae

Globicephala melas

long-finned pilot whale

 LC

137097

Mammalia

Cetartiodactyla

Delphinidae

Grampus griseus

Risso's dolphin

 LC

137098

Mammalia

Cetartiodactyla

Delphinidae

Orcinus orca

orca

DD

137102

Mammalia

Cetartiodactyla

Delphinidae

Pseudorca crassidens

false killer whale

 NT

137104

Mammalia

Cetartiodactyla

Delphinidae

Stenella coeruleoalba

striped dolphin

 LC

137107

Mammalia

Cetartiodactyla

Delphinidae

Stenella frontalis

Atlantic spotted dolphin

 LC

137108

Mammalia

Cetartiodactyla

Delphinidae

Tursiops truncatus

bottlenose dolphin

 LC

137111

Mammalia

Cetartiodactyla

Kogiidae

Kogiidae n.i.

kogiidae

136982

Mammalia

Cetartiodactyla

Kogiidae

Kogia breviceps

pygmy sperm whale

 LC

137113

Mammalia

Cetartiodactyla

Physeteridae

Physeter macrocephalus

sperm whale

 VU

137119

Mammalia

Cetartiodactyla

Ziphiidae

Ziphiidae n.i.

beaked whale

136986

Mammalia

Cetartiodactyla

Ziphiidae

Hyperoodon ampullatus

North Atlantic bottlenose whale

 NT

343899

Mammalia

Cetartiodactyla

Ziphiidae

Mesoplodon bidens

Sowerby's beaked whale

 LC

137121

Mammalia

Cetartiodactyla

Ziphiidae

Mesoplodon densirostris

Blainville's beaked whale

 LC

137122

Mammalia

Cetartiodactyla

Ziphiidae

Mesoplodon mirus

True's beaked whale

 LC

137126

Mammalia

Cetartiodactyla

Ziphiidae

Ziphius cavirostris

Cuvier's beaked whale

 LC

137127
Reptilia

Testudines

Cheloniidae

Cheloniidae n.i.

cheloniid

987094
Reptilia

Testudines

Cheloniidae

Caretta caretta

loggerhead turtle

 VU

137205
Reptilia

Testudines

Cheloniidae

Chelonia mydas

green turtle

 EN

137206
Reptilia

Testudines

Dermochelyidae

Dermochelys coriacea

leatherback turtle

 VU

137209
Taxa included:
Rank Scientific Name Common Name
order Cetartiodactyla Cetaceans
order Testudines Sea turtles

Temporal coverage

Data range: 
2009-1-01 - 2020-12-31.
Notes: 

Data were collected year-round in São Miguel and on a seasonal basis in Faial, Pico and Terceira.

Usage licence

Usage licence: 
Other
IP rights notes: 

Creative Commons Attribution 4.0 Internacional

Data resources

Data package title: 
MONICET: Long-term cetacean monitoring in the Azores, based on whale watching observations (2009-2020).
Resource link: 
https://doi.org/10.14284/599
Alternative identifiers: 
https://www.vliz.be/imis?dasid=7948
Number of data sets: 
1
Data set name: 
MONICET: Long-term cetacean monitoring in the Azores, based on whale watching observations (2009-2020).
Character set: 
UTF-8
Download URL: 
https://mda.vliz.be/download.php?file=VLIZ_00000772_642fe989615ef444113174
Data format: 
Darwin Core Archive (DwC-A)
Data format version: 
1.8.2
Description: 

The dataset includes all the records of cetaceans and turtles reported to the MONICET platform by whale watching companies in the Azores between 2009 and 2020 (Azevedo et al. 2023). It has been published as a Darwin Core Archive (DwCA), a standardised format for sharing biodiversity data as a set of one or more data tables. Data are available from OBIS, GBIF, EMODNET and IPT, all serving as a data repository. The core data table, the eventTable (Table 3), contains 37855 events, considering each observation as a separate event with a specific location and time. Each event belongs to a parentEvent corresponding to the whale watching trip in which it was recorded (in total, 8455 trips registered). The dataset also contains two extension tables linked to the core with the eventID field. The occurrenceTable (Table 4) contains 77572 occurrences, from which 374 are identified to family level and the rest correspond to 25 different species; and the eMoFTable (Table 5) contains 199792 measurements or facts related to each event (visibility or sea state) and/or to each occurrence (number of individuals, behaviour, life stage and sampling instrument).

Table 3.
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Description of variables in the eventTable.

Column label

Column description

type

Refers to the type of sampling: 'cruise' (for each whale-watching trip) or 'sample' (for each encounter)

institutionCode

University of the Azores, whose acronym is 'UAc'.

datasetName

All records are derived from the 'MONICET' dataset.

eventID

Unique identifier for each encounter (i.e. sampling event) in the dataset. Composed of the 'parentEventID' + the number of the encounter (as 'encounter00000').

parentEventID

A unique identifier that groups potentially several events. In this case, each whale-watching trip is considered a parent event. The ID is composed by 'institutionCode' + 'datasetName' + number of whale-watching trip (as 'cruise0000').

samplingProtocol

All the encounters were recorded as 'visual observation from whale watching boat'.

eventDate

Date and time, or time interval when available, when an encounter was registered. Formatted as 'YYYY-MM-DDT00:00/YYYY-MM-DDT00:00'.
minimumDepthInMetres Minimum depth at which the sighting was recorded (always 0 m, as animals are observed on the surface).
maximumDepthInMetres Maximum depth at which the sighting was recorded (always 0 m, as animals are observed on the surface).

decimalLatitude

The latitude (in decimal degrees, using the spatial reference system in geodeticDatum) of the location of the encounter.

decimalLongitude

The longitude (in decimal degrees, using the spatial reference system in geodeticDatum) of the location of the encounter.

geodeticDatum

The ellipsoid, geodetic datum or spatial reference system (SRS) upon which the geographic coordinates given in decimalLatitude and decimalLongitude are based.

footprintWKT

A Well-Known Text (WKT) defines the location. It includes all the locations assigned to an event: a multipoint string for all the locations of a whale-watching trip (cruise); a line string or a point for the location(s) of an encounter.
Table 4.
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Description of the variables in the occurrenceTable.

Column label

Column description

collectionCode

Abbreviation of the dataset name, in this case, MONICET.

basisOfRecord

The specific nature of the data record, in this case, all as HumanObservation.

occurrenceID

Unique identifier for each occurrence within an event in the dataset. Composed of eventID + the 3-letter code for the species and APHIA-ID + life stage (adult, juvenile or calf).

recordedBy

Name of the whale watching company contributing the information.

occurrenceStatus

Statement about the presence or absence of a taxon at the specified location. All the occurrenceStatus in this database are present.

eventID

Unique identifier for each encounter or sampling event in the dataset. Composed of the parentEventID + the number of the encounter (as 'encounter00000').

scientificNameID

Life Sciences Identifier (LSID) assigned to the taxon by WoRMS.

scientificName

The full scientific name.

scientificNameAuthorship

The authorship information for the scientificName formatted according to the conventions of the applicable nomenclatural code.
Table 5.
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Description of the variables in the ‘eMoFTable’.

Column label

Column description

measurementID

Unique identifier for the MeasurementOrFact (information on measurements, facts, characteristics or assertions). Composed of eventID + measurementType.

occurrenceID

Unique identifier for each occurrence within an event. Composed of eventID + the 3-letter code for the species and AphiaID + life stage (adult, juvenile or calf). The same encounter can include different occurrences of the same species, one per life stage.

measurementType

The nature of the measurement, fact, characteristic or assertion. The options available in this dataset are Beaufort wind force, behaviour, individualCount (best estimate), life stage (adult, juvenile or calf), sampling instrument name and visibility.

measurementTypeID

Definition according to the NERC Vocabulary Server (NVS) managed by the British Oceanographic Data Centre (BODC).

measurementValue

The value of the measurement, fact, characteristic or assertion. In this dataset: level of Beaufort wind force; behaviour (foraging, resting, socialising, travelling); individualCount (best estimate) (number of individuals sighted); and visibility (0-1000 m, 1000-5000 m, 5000-10000 m, >10000 m).
measurementValueID British Oceanographic Data Centre BODC codes for the measurement values.

measurementUnit

The units associated with measurementValue.
measurementUnitID British Oceanographic Data Centre BODC codes for the measurement units.
Column label Column description
parentEventID Each whale watching trip.
eventID Each encounter with cetacean or turtle observations.
occurrenceID The species and respective life stage recorded.

Additional information

Data collection for MONICET follows a well-defined protocol developed with several experts and the companies involved and widely shared. It standardises data collection and is compatible with the work onboard a whale watching vessel, while simultaneously recording scientifically useful information. Regular training sessions of company staff are conducted at least once a year, as this has proven to be effective to maintain company engagement and to enhance the long-term commitment from both sides.

The dataset provides ecological information about an extended group of cetacean species, including some whose global conservation status is a cause for concern, either Endangered (2 species), Near Threatend (2 species), Vulnerable (2 species) or even Data Deficient (1 species). The set of species convered by this database also corresponds to a wide range of ecological categories, from residents to seasonal visitors and others passing by in their annual migrations (Silva et al. 2014).

While the present dataset therefore constitutes a unique source of information on many aspects of cetacean biology and ecology, its sources of bias should be understood to minimise misuse and avoid misleading conclusions (Fernandez et al. 2018, Fernandez et al. 2021, González García et al. 2022a).

One of the main limitations of the dataset is the lack of absolute quantification of effort. In fact, whereas animals are mostly detected from land observations, the selection of what species to see (and therefore to record) is strongly influenced by commercial preferences. Boats will often prioritise shorter distances to the base port, locations with better sea conditions or even more appealing behaviour or species preferred by customers. For instance, a family of sperm whales or a playful group of dolphins would prevail over an elusive beaked whale or a diving whale away from the location of the boat. Notwithstanding, all companies follow approximately the same modus operandi, conducting trips of 2.5 to 3 h on average in the morning and in the afternoon and following the instructions given from land by specialised observers. At the same time, there is also a constant search effort by the boat crew at sea. No associated land observation recordings or boat tracks are available for this dataset. Both could be of interest to assess the scope and duration of land search and miles sailed by WW boats, which could be used as proxies for relative effort.

Species identification is assumed to be of high quality, given that the persons recording the data (the tour guides and boat skippers or interns supervised by them to assist on data collection) are highly experienced and often have Marine Biology degrees. However, precautions must be taken with particular taxa: (1) beaked whales (especially Mesoplodon spp.), whose species determination is difficult at sea due to their short time at the surface and often elusive behaviour; (2) Bryde’s whales, whose sighting frequency seems to be increasing, but may still be confused mainly with sei whales; and (3) the short-finned and long-finned pilot whales, which are difficult to differentiate at sea. Companies are instructed to record the predominant behavioural state at the time of arrival (foraging, resting, socialising and travelling). However, the behaviour at the boat's arrival can still be influenced by it or can result from the previous presence of other boats in the area (see, for the Azores, Visser et al. (2010), Cecchetti et al. (2017), Oliveira et al. (2022)). Additionally, sightings are often of short duration (a few minutes), so main behaviour is not always possible to assess in this short time. For instance, dolphins often interrupt their primary behaviour when the boat arrives and may only resume it when the boat leaves (e.g. dolphins stop travelling and bow-ride the boat for a while; thus, socialising instead of travelling will be recorded). Finally, caution is needed regarding the registered number of individuals. This generally corresponds to the individuals sighted from the boat, which does not necessarily agree with the number of individuals in the area. For instance, boats may record the number of dolphins of only a subgroup of a larger group of which they are not aware. Another common situation frequently happens with sperm whales, where independent individual sightings at a close distance and within a short time, may be registered instead of what was in fact one group of animals. This often happens, particularly with foraging behaviour (e.g. fluking). Additionally, data analyses should bear in mind that each sighting may be recorded by different boats simultaneously, as different companies work in the same area and often target the same encounters. The data presented here have been voluntarily collected manually, written on a paper at sea and typed into the database upon return to land, often not immediately and sometimes by another person. This process may lead to errors, particularly in geographical coordinates. A validation process, where a team with scientific supervision reviews every record, aims to minimise these errors, but inconsistencies may still be found.

From an academic perspective, MONICET data have been widely used by Biology students at the University of the Azores. Marine Mammals' classes are attended every year by dozens of students who actively explore the database and get hands-on experience with cetacean research and actual data. For the scientific community, the MONICET dataset’s fine-scale sampling, with long-term and regular cover in space and time in several islands of the archipelago, greatly complements traditional dedicated surveys, which often focus on more specific questions and covering shorter time periods. Insights that can be obtained with this kind of data include: (i) habitat preferences, (ii) seasonality, (iii) long-term changes or trends in distribution patterns or relative abundance, in correlation with oceanic variables or (iv) evidence of rare events, such as the presence of cryptic species, anomalous pigmentations or unusual types of behaviour.

Additionally, FAIR principles are considered to pursue better-quality scientific outputs (Wilkinson et al. 2016): (1) the dataset has associated metadata to facilitate computer reading and findability; (2) data have been published and made freely accessible online in different biodiversity repositories; (3) data have been standardised as far as possible following the international standards for biodiversity data to ensure interoperability; (4) biases and limitations are provided to minimise misinterpretation of the dataset and encourage proper use of it. Nonetheless, due to its opportunistic nature, caution is required when interpreting results derived from this database.

Over more than three decades of activity, whale watching has indeed evolved in the Azores, achieving high-quality benchmarks and successfully joining tourism, education and research. MONICET, together with all the partners and companies involved, has showcased its vast potential to maintain low-cost, long-term monitoring of cetaceans in the Azores. It has proved not only its scientific worth, but also the added value it brings for the whale watching companies and society at large.

Acknowledgements

The MONICET project has been a collective effort since the start and the people involved have been too many to acknowledge individually. We must nevertheless acknowledge the vision and leadership of the participating whale watching companies, from the founders (Futurismo Azores Adventures, Picos de Aventura and Terra Azul) to all the others who have joined this effort when it entered its growth phase (Aqua Açores, Atlantiangra, Azores Experiences, Espaço Talassa, Peter Whale Watch, Ocean Emotion, Sea Colors and Terra do Pico). In particular, we must recognise the effort of so many guides and skippers who have collectively spent thousands of hours collecting information and entering it manually on a computer keyboard, often after a hard day’s work. A special acknowledgement must also go to all the volunteers and interns who have helped with data validation and photo-id. The collaboration of all these entities and people has been (and will remain) essential to maintain this pioneer and globally-relevant work on long-term cetacean monitoring.

References

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