The use of natural markings to study the demography and social structure in common minke whale (Balaenoptera acutorostrata) and white-beaked dolphin (Lagenorhynchus albirostris)

• Main Author: Bertulli, Chiara Giulia, 1980-
• Other Authors: Háskóli Íslands
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2015
• Subjects: Doktorsritgerðir; Breiðafjörður; Faxaflói; Skjálfandi; Balaenoptera acutorostrata; Iceland; Lagenorhynchus albirostris; minke whale; White-beaked dolphin
• Online Access: http://hdl.handle.net/1946/23212

The demography and social structure were investigated in a whale (common minke whale; Balaenoptera acutorostrata) and a dolphin species (white-beaked dolphin; Lagenorhynchus albirostris) that are both abundant yet poorly understood within Icelandic coastal waters. Analysis were conducted from 12 years (2002–2014) of photo-identification data collected from onboard whale-watching boats in Faxaflói and Skjálfandi with some additional images obtained from colleagues working in Breiðafjörður. Stranding reports from outside of Iceland were also used to better understand our knowledge on the occurrence of veterbral column deformities in white-beaked dolphins. We first assessed the prevalence, abundance and rates of change of 28 naturally occurring mark types that could be used for capture-mark-recapture studies of both species. Results suggested fin and body injury marks were among the most accurate features to use for capture-mark-recapture studies as noted for other cetacean species. However, our results also suggested that cookie-cutter shark bites for common minke whales and fin patches for white-beaked dolphins could also be used due to their low loss rate, which was a novel realisation that will ultimately increase sample sizes for any database for both species. We explored the occurrences of vertebral column deformities of white-beaked dolphins from free-ranging and stranded specimens across Europe. The results indicated that vertebral column deformities occur in this species and that some individuals can live with such anomalies for several months. Five white-beaked dolphins showed outwardly vertebral kyphosis, kyphoscoliosis or lordosis. Two of the free-ranging cases and two of the stranded specimens appeared to have an acquired disease, either as direct result of trauma, or indirect from trauma/wound and subsequent infection and bony proliferation, although we were unable to specifically identify the causes. These results represent a good starting point to understand occurrence and implications of vertebral ...