Characteristics of whale sharks (Rhincodon typus) in Teluk Cenderawasih National Park, Indonesia

Abstract

Background The whale shark (Rhincodon typus) is an iconic species for Teluk Cenderawasih National Park (TCNP), West Papua and Papua. They appear regularly near lift-net fisheries (bagans) year round in some areas, especially near Kwatisore in West Papua, resulting in the development of limited tourism since 2009. The objective of our study was to document the characteristics (i.e., number, size, sex) of whale sharks that occur in TCNP. Approach We used photographs to identify whale sharks from natural patterns and other body markings that periodically appeared near operational bagans in southern Cenderawasih Bay. The photo ID technique was used to identify each individual based on the white body spot pattern. We also made subjective estimates of the relative sizes of each shark and determined whether they were male or female from the presence or absence of claspers. Results We obtained 8,530 photos of sharks from February 2010 through June 2015. From that database we tentatively identified 126 sharks, 83% of them male, 14% female and 3% undetermined. The estimated length of the sharks averaged 4.4 m (± 1.25 m, range = 2 m to 8 m). Around 40% of the individuals had scars, mostly around their mouths and fins. Most (59%) of the sharks were seen in one year, while only 3% were seen over more than one year during the five year study. Some exceptions were one shark that was seen 32 times over four years, and another that was seen 29 times over five years. Conclusions Juvenile male whale sharks appear to be transient and highly mobile in Cenderawasih Bay. Whether adult males or adult females occur here is not known, as they may not be attracted to the fishing bagans or do not otherwise approach the sea surface where they can be observed. Because of the increased tourism for whale sharks and the interactions of whale sharks with the fishing bagans, we recommend continued systematic observations of whale sharks and vigilant surveillance for understanding the dynamics of interactions among tourist activities, fishing operations, and whale sharks.