Cetacean distribution and relative abundance in Colombia's Pacific EEZ from survey cruises and platforms of opportunity

• Main Authors: Palacios, DM, Herrera, JC, Gerrodette, T, Garcia, C, Soler, GA, Avila, IC, Bessudo, S, Hernandez, E, Trujillo, F, Florez-Gonzales, L, Kerr, I
• Format: Article in Journal/Newspaper
• Language: English
• Published: International Whaling Commission 2012
• Subjects: Environmental Sciences; Environmental Science and Management; Conservation and Biodiversity; Pacific; Balaenoptera acutorostrata; Balaenoptera physalus; Fin whale; Humpback Whale; Killer Whale; minke whale; Orca; Orcinus orca; Physeter macrocephalus; Sperm whale
• Online Access: https://www.researchgate.net/publication/230630801_Cetacean_distribution_and_relative_abundance_in_Colombia%27s_Pacific_EEZ_from_survey_cruises_and_platforms_of_opportunity; http://ecite.utas.edu.au/128473

Cetacean sighting data collected under various programmes in Colombian Pacific waters were collated with the goal of assessing the distributionand abundance patterns of all species occurring in the exclusive economic zone (EEZ). Distribution maps are presented for 19 species and onegenus based on 603 sightings collected between 1986 and 2008. Ordered by sighting frequency, these species were: humpback whale (Megapteranovaeangliae); striped dolphin (Stenella coeruleoalba); common bottlenose dolphin (Tursiops truncatus); pantropical spotted dolphin (Stenellaattenuata); common dolphin (Delphinus delphis); Rissos dolphin (Grampus griseus); sperm whale (Physeter macrocephalus); rough-tootheddolphin (Steno bredanensis); short-finned pilot whale (Globicephala macrorhynchus); mesoplodont whales (Mesoplodon spp.); Cuviers beakedwhale (Ziphius cavirostris); melon-headed whale (Peponocephala electra); false killer whale (Pseudorca crassidens); killer whale (Orcinus orca);spinner dolphin (Stenella longirostris); dwarf sperm whale (Kogia sima); Brydes whale (Balaenoptera edeni); pygmy killer whale (Feresaattenuata); minke whale (Balaenoptera acutorostrata) and fin whale (Balaenoptera physalus). Concentrations of sightings were observed in threegeographic areas: (1) the continental shelf (depths <200m) and the contiguous continental slope (2002,000m); (2) over the Malpelo Ridge, anoffshore bathymetric feature and (3) the northeast corner of the EEZ between Golfo de Cupica and the border with Panam, although we do notrule out that these patterns could be an artefact of non-random effort. In inshore waters, the most frequently seen species were pantropical spotteddolphin, common bottlenose dolphin and humpback whale. For several of the data sets we provide encounter rates as indices of relative abundance,but urge caution in their interpretation because of methodological limitations and because several factors that affect sightability could not beaccounted for in these estimates. Our results provide useful information for ongoing regional research and conservation initiatives aimed atdetermining occurrence, population status and connectivity within adjacent EEZs in the eastern tropical Pacific. Suggested research priorities includeconducting dedicated surveys designed for estimating abundance and monitoring trends throughout the EEZ and focused studies in areas of specialinterest like the continental shelf, the Malpelo Ridge and the vicinity of Cupica and Cabo Marzo. More research is also needed in terms of quantifyingthe sources and impact of anthropogenic mortality on population size. Studies characterising genetic diversity and stock discreteness in coastalspecies (pantropical spotted dolphin and common bottlenose dolphin) would help inform local management strategies.