A Summary of Effort

Summer 2000 – Mikura Dolphin Research

I spent 20 days in June and 15 days in July on Mikura Island with the potential to go to sea to observe dolphins. Data were collected in the form of video records and a written sighting record for where and when dolphins were observed. Dolphins were observed in all locations around Mikura with many sightings below Nango or at Otaura. I had 14 boat trips resulting in 32 hours and 15 minutes of effort spent searching for dolphins. During that time, more than 5 hours were spent underwater with about 140 minutes of video gathered with dolphins in view. The return on effort expended is 7.34% (140/1935 min). Five new calves were observed during the tenure of my 2000 field season. The last one was probably born on Tuesday, 11 July, since the adult female was documented on video as pregnant on 10 July and the same female was seen on 12w July with a brand new calf. Six classes of age/gender have been documented by the Mikura Iruka Kyoukai for this dolphin group: adult female (AF), sub-adult female (SF), juvenile female (JF), adult male (AM), sub-adult male (SM), and juvenile male (JM). Infants are added to the identification catalog only when they possess individually distinctive scars and can be reliably re-identified. The study population consists of at least 188 individually identified bottlenose dolphins. During my field season, the following numbers of each category have been positively identified. This number is likely to increase since all possible identifications have yet to be confirmed from my video records. Currently, 70 indidividual bottlenose dolphins have been identified in my video records. AF – 23            AM – 8 SF – 8            SM – 25 JF – 3            JM – 3 We also confirmed the sex of one juvenile female during this season. When I return to the USA, I will be able to digitize some of my video to give you a few pictoral examples of some of the dolphins in this study group. Cheers for now. Kathleen