For its massive size, we know very little about whale sharks (Rhincodon typus). Much of their ovovivparous reproductive mechanisms are known from only a single pregnant female which was commercially caught by harpoon in Taiwan in July 1995 (Joung, Chen, Clark, Uchida, & Huang, 1996). The “megamamma” was found to have over 300 developing embryos, all at different stages of development. Some still remained in their egg cases, while others were free of their egg cases and yolk sacs (Joung, et al., 1996). This suggests that the whale shark has long parturition periods and give birth in bursts over several days, weeks, or even months as the young reach their fully developed neonate stage (Joung, et al., 1996). Since the discovery, both pregnant females and neonates have been documented in several areas throughout the world, suggesting these sites may be nursery habitats (Martin, 2007). However, no one has ever witnessed a whale shark giving birth; and while there are reports of mating taking place in Mexico’s Yucatán Peninsula, no one has ever managed to capture the behavior on film… until now!
For the first time ever, researchers have witnessed the mating behavior of whale sharks and managed to capture the behavior on film earlier this month. Ningaloo Reef in Western Australia is a known hot spot for whale sharks in the winter months (Wilson, Polovina, Stewart, & Meekan, 2006). Tiffany Klein, a pilot with Ningaloo Aviation, was aerial spotting for CSIRO researchers when she spotted a large 30 foot (9 m) male approaching a smaller female.
Klein told ABC that the male had been acting, “erratically, zigzagging around and up and down quite quickly” (Gudgeon, 2019). CSIRO researcher Dr. Richard Pillans, who has been studying the DNA of whale sharks in Ningaloo Reef to learn more about their behavior and populations, watched the spectacle from the boat. As the male approached the female, there was commotion as the male completely turned upside down beneath the female. Dr. Pillans recalled that the male’s claspers were flared as he attempted to mate with the female. Sadly, his efforts were not reciprocated by the smaller, immature female.
While this particular mating session may not have been productive, the fact that males are actively seeking out a mate suggests that Ningaloo Reef does play a role in whale shark mating. This encounter also raises more questions about where females go following mating. A question that Dr. Pillans hopes to shed more light on. The five year project has been a collaboration between CSIRO and BHP. The project has involved the placement of satellite tags to track the whale shark’s movements, as well as collecting DNA samples. The study is revealing that the populations that visit Ningaloo Reef as virtually identical to those on the opposite side of the Indian Ocean, supporting previous tagging studies that have revealed the vast migrations these sharks take (Graham & Roberts, 2007; Hueter, Tyminski, & de la Parra, 2013; Stevens, 1999; Wilson, Polovina, Stewart, & Meekan, 2006).
Research into whale sharks mating behaviors and where they pup is crucial for their conservation and future survival. Previously considered Vulnerable by the International Union for the Conservation of Nature (IUCN), their status has been upgraded to Endangered due to accidental entanglement, boat strikes, and habitat degradation, pollution throughout its range, as well as targeted and bycatch fisheries (Pierce, & Norman, 2016). Protecting important mating, pupping, and feeding, like Ningaloo Reef, may help ensure the whale shark’s survival and population recovery. This is an exciting step towards understanding these incredible sharks.
Flannery, A. (Videographer). (2017). Whale Sharks of La Paz [Video Clip]. Retrieved from https://www.youtube.com/
The new Ocean For Sharks Shop is open! There’s handmade ocean inspired plush animals, canvas paintings, and of course my children’s book, Winifred the Wondrous Whale Shark, available in print and PDF. Be sure to stop by. Proceeds benefit shark research and conservation with a donation to Project AWARE!
Thanks so much for checking out the wild Smooth Hammerhead! If you missed last week’s featured species, please be sure to check out the elusive Longfin Mako! If there is a species of elasmobranch you’d love to know more about, leave me a comment or send me a message! I would love to do a feature on your favorite species. Also connect with me on Instagram and Facebook for even more elasmo fun!
Conservation legislation needs public support in order to become law and help protect the environment and wildlife. Tell your representatives that you care about environmental and wildlife conservation. It only takes a moment to make a change that will last a lifetime. Until next time finactics!
Featured Image Source
Klein, T. (Photographer). (2019). Ningaloo Aviation pilot Tiffany Klein captures a male whale shark attempting to mate with a smaller female whale shark [Digital Image]. https://facebook.com
Graham, R. T., & Roberts, C. M. (2007). Assessing the size, growth rate and structure of a seasonal population of whale sharks (Rhincodon typus Smith 1828) using conventional tagging and photo identification. Fisheries Research, 84(1), 71–80.
Gudgeon, K. (2019). Rare glimpse of mating whale sharks excites scientists. Retrieved June 24, 2019, from https://www.abc.net.au/
Hueter, R. E., Tyminski, J. P., & de la Parra, R. (2013). Horizontal Movements, Migration Patterns, and Population Structure of Whale Sharks in the Gulf of Mexico and Northwestern Caribbean Sea. PLoS ONE, 8(8).
Joung, S.-J., Chen, C.-T., Clark, E., Uchida, S., & Huang, W. Y. P. (1996). The whale shark, Rhincodon typus, is a livebearer: 300 embryos found in one “megamamma” supreme. Biology of Fishes, 46(Baughman 1955), 219–223.
Martin, R. A. (2007). A review of behavioural ecology of whale sharks (Rhincodon typus). Fisheries Research, 84(1), 10–16.
Pierce, S.J. & Norman, B. (2016). Rhincodon typus. The IUCN Red List of Threatened Species. Retrieved from https://www.iucnredlist.org/
Stevens, J. D. (1999). Shark tagging: a brief history of methods. Fish Movement and Migration, 65–68.
Wilson, S. G., Polovina, J. J., Stewart, B. S., & Meekan, M. G. (2006). Movements of whale sharks (Rhincodon typus) tagged at Ningaloo Reef, Western Australia. Marine Biology, 148(5), 1157–1166.