Laura González1,2, Miranda van der Linde1 , Clara Sardà1 & Jesús Torres-Palenzuela2
1 Futurismo Azores Whale Watching, Ponta Delgada, São Miguel, Azores.
2 Department of Applied Physics, Vigo University, Vigo, Spain.
Corresponding author: firstname.lastname@example.org
Data of dolphin sightings were collected off the south coast
of São Miguel during whale watching tours between 2009 and
2011. We used GEBCO Bathymetry data set downloaded from
http://www.bodc.ac.uk, and sea surface temperature data
gathered from http://www.myocean.eu.
• 384 sightings between 2009 and 2011 (168, 90 and 126
respectively). The 4th most sighted species of the study period.
•Recorded very year between June and December, mostly
between July and September (75%). Some records in January
and February of 2009 (Fig.1A).
•Encountered when sea surface temperature was within
16.9ºC and 24.5ºC, having 69.8% between 21ºC and 23.5ºC
The Atlantic spotted dolphin is more frequent in summer
months, according with the higher sea surface temperature.
They were not recorded under 16.8 ºC.
The 2009 winter sightings were probably due to the unusual
high sea surface temperature.
Whale watching companies are increasingly providing
useful sources of information, even with some limitations, to
understand the ecological patterns of marine mammals.
In this study we want to assess the temporal distribution of
Atlantic spotted dolphins (Stenella frontalis) off São Miguel
(Azores), looking as well at their preferences in depth and sea
surface temperature with data gathered between 2009 and
2011 during whale watching tours.
Most of the groups recorded were families with calves.
•71% of the sightings were recorded in depths under 900 m (Fig.2).
Rate of sightings of Atlantic spotted dolphin increases in
summer months, just when common dolphin sightings
decrease. It would be interesting to assess if there is some
niche competition between these species (perhaps feeding
competition?) as they seem to live in the same area at
•Groups were formed mainly by adults, juveniles and calves
(74.22%) and usually they included several hundred dolphins,
and even more than 1000 in 2009.
Fig.1. Sightings of the Atlantic spotted dolphin off São Miguel, Azores.
A) Temporal distribution. B) Sea surface temperature sightings.
Fig.2. Sightings of Atlantic spotted dolphins over the bathymetry map.