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Photo-identification catalogue and distribution of orcas (Orcinus orca) off São Miguel Island, Azores

Authors:

Abstract

Orcas (Orcinus orca) are widespread throughout the North Atlantic. However, their conservation status is still data deficient, and little is known about their populations and distribution, especially in mid-Atlantic waters like the Azores. Opportunistic data collected year-round on board whale watching vessels between 2006 and 2020 were used to assess the temporal distribution and create a photo-identification catalogue of the orcas sighted around São Miguel, Azores. Occurrence data and photographs for identification were collected by Futurismo Azores Adventures and MONICET project. Orcas were sighted in nine of the 15 years considered, mostly between March and May. Fifty-five individuals were identified, of which 17 were re-sighted, but not between different years. They usually remained in the area only for a few days, with the exception of one adult male that was re-sighted over three months in 2013. Photo quality and the limited study area are some of the limitations of this study. However, advantages such as long-term data with a regular spatial coverage, make whale watching platforms a highly valuable tool to improve our knowledge of orca populations in the North Atlantic.
Long-term data with a regular spatial coverage make whale watching companies a highly
valuable tool to improve our knowledge of orca populations in the North Atlantic. However, more
regular and good quality photographs would be of great value to extend the existing information.
Comparison with other catalogues, both within the Azores and in the North Atlantic, is necessary
to increase our understanding of the population structure, spatial and temporal coverage, movement
patterns, estimate populations size and better understand their biology and ecology.
Photo-identification catalogue and distribution of orcas (Orcinus orca)
off São Miguel Island, Azores
Cabayol, G.1, Navas, M.¹, Zimmermann, C.¹, González García, L.1,2
(1) Futurismo Azores Adventures, Ponta Delgada, Azores, Portugal. (2) Azorean Biodiversity Group, Centre for Ecology, Evolution and Environmental Changes (CE3C) University of the Azores, Portugal.
Introduction
Orcas (Orcinus orca)are widespread throughout the North Atlantic. However, their
conservation status is still data deficient, and little is known about their populations and
distribution, especially in mid-Atlantic waters like the Azores1.
The aims of this study are:
1. To create a photo-identification
catalogue of orcas off São Miguel,
Azores.
2. To assess the temporal distribution of
orcas sighted around São Miguel, Azores.
Opportunistic data were collected year-round between 2006 and 2020 during whale
watching tours with Futurismo Azores Adventures in São Miguel Island (Azores)
(Fig.1). Additionally, data from the MONICET platform (www.monicet.net) was used to
complete the final photo-identification catalogue and distribution analysis.
Good quality photos were used for
individual identification, based on
the shapes, marks such as nicks,
scratches and coloration patterns of
the dorsal fins, saddles, eye patches,
flukes and bodies2,3.
Fig. 3. Temporal distribution of orcas off São Miguel (2006-2020). Only years
and months with sightings are shown on the graph.
Fig. 2. Re-sighting of a male orca in January, April and May 2013 (SM_FUT_Oo09).
References. 1Jourdain E, Ugarte F, Víkingsson G, Samarra F, Ferguson S, Lawson J,Vongraven D, Desportes G. 2019. North Atlantic killer whale
Orcinus orca populations: a review of current knowledge and threats to conservation. Mammal Review,49(4), 384-400;2Foote AD, Kuningas S, Samarra
FI.2014. North Atlantic killer whale research: past, present and future. Journal of the Marine Biological Association of the United Kingdom,94(6), 1245-
1252.3Young B, Higdon J, FergusonS. 2011. Killer whale (Orcinus orca) photo-identificationin the eastern Canadian Arctic. Polar Research,30(1), 7203.
ACKNOWLEDGEMENTS. We would like to thank Futurismo Azores
Adventures team, and the MONICET project who have collected data for this
study. Thanks to Ida Eriksson fo r the first Futurismo Orca catalogue.
Fig. 1. Sightings of Orcinus orca in the study area (2006-2020).
Corresponding author: georginaferraz@futurismo.pt
08/01/2013 10/05/201304/04/2013
Orcas were sighted 46 times on 33
different days, in 9of the 15 years
considered.
Re-sightings:
16 individuals in consecutive days
(max.45 days).
1 adult male re-sighted over five
months in 2013 (Fig.2).
Whale watching vessels were guided
by lookouts located on land.Once
with the animals, photographs were
taken when possible, and data such as
date and GPS location, were
registered for each sighting.
Photo-ID
Temporal distribution
Photo by Rafael Martins
Methods
Results & Conclusions
Looking forward
55 individuals identified
(35 both sides, 7 right, 13 left side)
Orcas occur around São Miguel
mainly between March and May
(Fig.3).
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