Baleen whales sighted occasionally in the Azores: Bryde's whale, minke whale and humpback whale.

Abstract

Around the archipelago of the Azores it is possible to see more than 24 species of whales and dolphins. These species can be divided into three groups according to the period and
frequency of sightings: residents that are sighted throughout the whole year; seasonal species that occur during specific time periods; and occasional species that are sighted only rarely. We found that Brydeڇs whales (Balaenoptera edeni), minke whales (Balaenoptera acutorostrata) and humpback whales (Megaptera novanglieae) belong to the latter group. In order to assess the occurrence of these three species we analysed data collected during commercial whale watching tours with Futurismo Azores Whale Watching. The data we analysed were from encounters between 2006 and 2012 off the south coast of São Miguel Island (Azores). Bryde's whales were seen only at the end of August of 2009 during five encounters on four different days. Minke whales were encountered on 15 occasions, mostly in March-April of 2010, 2011and 2012, although in 2006 they were sighted in November and in 2009 in August. Humpback whales were also sighted on 15 occasions, but with a larger temporal distribution as they were
sighted across all seasons of the year. Humpback whales sighted during the last three years were photographically identified to make up a catalogue of 11 different individuals. One whale was resighted after only seven days, but there were no other resightings between seasons or years. Being baleen whales it is likely that they are passing the Azores during their migrations between their breeding grounds and the North Atlantic feeding grounds. However, more studies are required to better understand the occurrence of these species in the Azores.

Full text

BALEEN WHALES SIGHTED OCCASIONALLY IN
Miranda van
der Linde
AD33
Miranda van der Linde1, Laura González1,2 & Clara Sardà1
(1) Futurismo Azores Whale Watching, Marina Pêro Teive, 9500-771, Ponta Delgada, São Miguel, Azores
(2) Department of Applied Physics, Vigo University, Vigo, Spain
Corresponding author: miranda.vanderlinde@gmail.com
THE AZORES: BRYDE’S WHALE, MINKE WHALE
AND HUMPBACK WHALE
INTRODUCTION
In the Azores archipelago sightings of Bryde’s whales (Balaenoptera edeni), minke whales (Balaenoptera
acutorostrata) and humpback whales (Megaptera novaeangliae) are rare and poorly understood in
comparison to other baleen whale species1,2.We analysed long-term sighting data from opportunistic
research to assess the occurence of these three species along the south coast of São Miguel Island, Azores.
Encounter data were collected from
several different vessels during
commercial whale watching tours with
watching tours with Futurismo Azores
Whale Watching in São Miguel. Animals
were found visually by one or more
experienced land-based observers along
the south coast of the island. Data
collected from encounters between 2006
and 2012 were analysed for patterns in
temporal distribution. During most of our
encounters photographs were taken of all
whales encountered. Humpback whales
were photographically identified and
catalogued based on the marks on the
dorsal fin and ventral surface of the flukes.
Encounters registered between 2006 and 2012:
•Bryde’s whale: 5 encounters on 4 different days
(only in August 2009)
•Minke whale: 15 encounters on 13 different days
(mostly in March-April of 2010,2011 and 2012)
•Humpback whale: 18 encounters on 15 different days
(large temporal distribution across all seasons of the year)
Data were collected during opportunistic encounters from
aboard several different vessels during commercial whale
1) Mónica, A., Silva, R., Prieto, S., Magalhães, R., Cabacinhas, A., Cruz, J.M., Conçalves & R.S. Santos (2003).
Occurence and distribution of cetaceans in the waters around the Azores (Portugal), Summer and Autumn
1999-2000.Aquatic Mammals 29(1): 77-83.
2) Steiner, L., Silva, M.A., Zereba, J. & Leal, M.J. (2008). Bryde’s whales, Balaenoptera edeni, observed in the
Azores: a new species record for the region. Journal of Marine Biology Association of the United Kingdom 1: 66
3) Visser, F., Hartman, K.L, Pierce, G.J., Valavanis, V.D. & Huisman, J. (2011). Timing of migratory baleen whales
at the Azores in relation to the North Atlantic spring bloom. Marine Ecology Progress Series 440:267-279.
Bryde’s whale – Balaenoptera edeni
Minke whale –Balaenoptera acutorostrata
We did not detect any patterns in
the occurence of all three species
during the study period.
•It is likely that humpback and minke
whales sighted in the Azores are
migrating between breeding grounds
and feeding grounds3, whereas rare
Bryde’s whale sightings may be due
to temporal range expansions of the
Eastern Atlantic population2.
•More studies on a larger temporal
and spatial scale are required to
better understand the occurence of
Bryde’s whales, minke whales and
humpback whales in the Azores.
Humpback whale –Megaptera novaeangliae
Good quality photos of humpback whales were taken
during 10 encounters. 12 different individuals were
identified, including 2 mother and calf pairs.
One juvenile whale was resighted after only 7 days. There
were no other resightings between seasons or years.
We would like to thank Futurismo Azores Whale Watching and all
biologists, guides and volunteers who
helped collect used data for this project.
Fig. 1. Temporal distribution of Bryde’s whales, minke whales and
humpback whales between 2006 and 2012 off São Miguel (Azores).
Fig. 2. Examples of photographically-identified humpback whales.
Mn2 and Mn3 are mother and calf respectively.
Mn2_fluke Mn3_flukeMn4_dorsal
2006
2007
2008
2009
2010
2011
2012
050 100 150 200 250 300 350 400
Year
day of the year
Bryde's whale
Minke whale
Humpback whale