Photo ID-based assessment of the whale shark (Rhincodon typus) population in Kwatisore, Wondama Bay, West Papua, Indonesia

Background The presence of whale sharks (Rhincodon typus) in Wondama Bay has long been known and the species is an icon of this region. In addition to their enormous size, these sharks are not dangerous to or fearful of humans, so there has been growing interest in utilizing this animal for eco-tourism. Within Wondama Bay, whale sharks distribute in several regions, including Kwatisore waters. Since biological information on this species is lacking, the present study aimed to investigate the whale shark population using photo identification, frequency of appearance, sex, and scars on the body. The information obtained from this study is important for species conservation and management. Approach The research was performed in Kwatisore waters of Wondama Bay during 2010–2013, and continued from April to June 2014. Whale shark identification was based on photos taken by divers by plotting three reference points, i.e. the top of the fifth gill slit, the posterior-most point where the pectoral fin meets the body, and the bottom of the fifth gill slit (Brooks et al., 2010). During each encounter, the animals were length measured, sex was identified through the presence or absence of claspers, and the position of scars and wounds were determined on the body. Results The total number of whale sharks encountered in Kwatisore waters were 120 and 19 animals for the period of 2010–2013 and 2014, respectively. Based on ID pictures, the population was composed of 126 sharks consisting of 122 males and 4 females. With regard to 2014 observations, the animals were all males and were immature, as the average body length was 4 m. The greatest number of sharks was observed between 0600–1200 hours, during which time 80 individuals were seen on the surface. It was found that 58% of the population had scars and wounds, of which 34% were on the lips and 25% on the fins. Conclusions Data on IDs and body length of each individual, as well as sex composition, are important information for understanding whale shark population structure, and will benefit the conservation and management of these animals.