Occurrence and rates of encounter of marine mammals in the waters of Malpelo Island and towards the continent
Herrera Carmona, JC and Capella Alzueta, JJ and Soler, GA and Bessudo, S and Garcia, C and Florez-Gonzalez, L, Occurrence and rates of encounter of marine mammals in the waters of Malpelo Island and towards the continent, Boletin de Investigaciones Marinas y Costeras, 40 pp. 57-78. ISSN 0122-9761 (2011) [Professional, Refereed Article]
Occurrence and encounter rates of marine mammals in the waters around the Malpelo
Island and to the continent. This work compiles a decade (2001-2010) of marine mammal sightings
in the Malpelo Fauna and Flora Sanctuary (FFS) and the area between the island and mainland coast.
Four separate sources of data were consulted, which used visual searching during cruising efforts while
Malpelo’s surrounding waters were surveyed from a vantage point. Seven species were identified in the
FFS: October and November were the months with higher species richness. Tursiops truncatus had the
highest encounter rates (17.78 groups/100 h), followed by Megaptera novaeangliae (1.62) and Stenella
attenuata (0.88). These species were usually within 6 km from the island. Other species seen around the
island include Stenella coeruleoalba, Delphinus delphis, Stenella longirostris and Zalophus wollebaeki.
On the other hand, thirteen species were identified during cruises, and March and April were the months
with the highest species richness. Megaptera novaeangliae had the highest encounter rate (5.94),
followed by T. truncatus (3.30), S. attenuata (3.08), D. delphis (3.08) and S. coeruleoalba, Globicephala
macrorhynchus and Orcinus orca, each one with 0.66. Other species seen during the cruises include Steno
bredanensis, Pseudorca crassidens, Grampus griseus, Peponocephala electra, Physeter macrocephalus
and Ziphius cavirostris. Megaptera novaeangliae were associated to the continental shelf, T. trunctaus
and D. delphis to oceanic waters, and S. attenuata to both the continental shelf and oceanic waters.
Delphinus delphis was more abundant in intermediate waters, during the first trimester (January-March),
while T. truncatus was the most abundant species around the Sanctuary during all seasons, suggesting
that is the same population. The latter was also the only species found all year round in both zones
(around the island and in oceanic waters), and encounter rates did not change across years. Megaptera
novaeangliae had a seasonal presence (mostly June to November) with a higher abundance during the
third trimester (July-September), both around Malpelo and the transect. The presence of humpback
whales calves suggests that Malpelo is used for reproductive purposes. This new information about the
marine mammals found in Malpelo FFS and the area between the island and the continent contributes to
the understanding of these species in Colombian waters.
Professional, Refereed Article
marine mammals, cetaceans, Colombian Pacific, Malpelo Island