Abundance estimate of the Amazon River Dolphin (Inia geoffrensis) and the tucuxi (Sotalia fluviatilis) in southern Ucayali, Peru

Elizabeth Campbell, Joanna Alfaro Shigueto, Brendan J. Godley, Jeffrey C. Mangel

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

We present results of the first simultaneous visual and acoustic surveys for Amazon River dolphins (Inia geoffrensis) and tucuxi (Sotalia fluviatilis), undertaken in Yarinacocha Lagoon, Ucayali, Peru (length = 20 km, area = 12 km2). A total of 324 Sotalia observations and 44 Inia observations were recorded in boat-based transects. Based upon total survey effort, we estimated Sotalia had a mean density ± SE of 1.98 ± 4.6 ind km-2and an overall abundance of 34 individuals (95% CI: 28 to 40). Average density for Inia was 0.2 ± 1.2 ind km-2with overall abundance estimated at 3 individuals (95% CI: 0 to 8). Visual surveys observed more Sotalia individuals during earlier hours of the day and during the dry season. Preliminary acoustic surveys undertaken with C-POD passive acoustic monitoring devices indicated a diel pattern in detections of cetacean vocalization with more diurnal activity and with detections ceasing from midnight until 10:00 AM. This work highlights the possibility of monitoring both river dolphin species through visual and acoustic surveys to generate baseline information on abundance trends and distribution patterns in the Ucayali region, an area with high levels of human disturbance.

Original languageEnglish
Pages (from-to)957-969
Number of pages13
JournalLatin American Journal of Aquatic Research
Volume45
Issue number5
DOIs
StatePublished - Nov 2017

Keywords

  • Abundance
  • Boto
  • C-POD
  • Echolocation loggers
  • Inia geoffrensis
  • Population
  • Seasonality
  • Sotalia fluviatilis
  • Tucuxi

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