Report of the Second Workshop on The Biology and Conservation of ...

APPENDIX 9Abstracts <strong>of</strong> Papers Presented atSymposium Immediately Before <strong>Workshop</strong>Monitoring <strong>of</strong> Cetaceans in <strong>the</strong> Sou<strong>the</strong>rn Tañon Strait Area through DolphinWatching Boats from Bais City, Negros OrientalAragones, Lemnuel V. 1 ; Clarion, Mae Ann 2 ; Merto, Rowena 3(1) Institute <strong>of</strong> Biological Sciences, University <strong>of</strong> <strong>the</strong> Philippines Los Baños, College, Laguna 4031(2) Dolphin Watching Unit, City Tourism Office, Bais City, Negros Oriental(3) Tourism Office, City Hall Compound, Sta Catalina St., Dumaguete City 6200Information ga<strong>the</strong>red from dolphin watching boats operated by Bais City Tourism Office atNegros Oriental allowed monitoring <strong>of</strong> cetaceans in <strong>the</strong> sou<strong>the</strong>rn Tañon Strait area from June1997 to April 2001. Some basic information including species composition, estimated herd size,presence or absence <strong>of</strong> calf, behavior, time and sea state were recorded. To date, ten species(spinner, spotted, Risso’s, bottlenose and Fraser’s dolphins, and pilot, melon-headed, pygmykiller, dwarf sperm, and pygmy sperm whales) have already been recorded. The most frequentlysighted species was <strong>the</strong> spinners (n= 494) followed by <strong>the</strong> spotted (n=187). The largest cetaceanspecies most frequently sighted was <strong>the</strong> pilot whale (n=74) followed by <strong>the</strong> melon-headed (n=33).The least sighted species include <strong>the</strong> pygmy sperm whale (n=2), Fraser’s dolphin (n=3) and <strong>the</strong>pygmy killer whale (n=6). The annual mean herd size for <strong>the</strong> spinner (a) and spotted (b) dolphinsappears to be increasing (1997 a= 28, b=33; 1998 a= 77, b=68; 1999 a=77, b=80; 2000 a=93, b=98;and 2001 a=132, b=154). The trend in <strong>the</strong> annual mean herd size for <strong>the</strong> pilot (a) and melonheaded(b) whales was almost similar (1997 a=42, b= 52; 1998 a=63, b=54; 1999 a=64, b=67; 2000a=56, b= 64). Cetacean abundance appears to peak during <strong>the</strong> lull between monsoons (April-May) and through <strong>the</strong> SW monsoon months (June-November). Calving for spinners and spottedappears to be dispersed throughout <strong>the</strong> year. However, peaks appear to occur during <strong>the</strong> months<strong>of</strong> April through August. Also, multi-species associations have <strong>of</strong>ten been observed betweenspinners and spotted, spinners and Risso’s, Risso’s and pilots, Risso’s and melon-headed, andsometimes between spinners and pilots, and among bottlenose, Risso’s and melon-headed. Thisstudy shows that a systematic collection and analyses <strong>of</strong> data from regularly operating dolphinwatching boats could serve as an important tool in monitoring cetaceans in a particular area.132 CMS Technical Series Publication Nº 9 - 2005