A study published this earlier this month in the journal of Pacific Conservation Biology has shed some light on the life history characteristics of the Australian Blackspot Shark (Carcharhinus coatesi) of Papua New Guinea and demonstrates the importance of studying data deficient populations. The Australian blackspot shark, also known as the Coates’s shark, is a small and slender shark has only recently bee designated as a separate species from the blackspot shark (Carcharhinus sealei) (Ebert, Fowler, & Dando, 2015).
It’s well established the biology and life history characteristics, including growth rates and age at maturity, can vary within a species region for a variety of reasons (Taylor, Harry, & Bennett, 2016). The Austrlian blackspot shark is a species native to northern Australia and Papua New Guinea (Ebert, Fowler, & Dando, 2015). In the previous studies, the life history characteristics of the Australian blackspot shark were studied within the Great Barrier Reef; however, the populations of New Guinea had yet to be studied prior to this study’s examination (Baje et al., 2019).
The regions in which the Australian blacknose shark inhabits throughout New Guinea are some of the most exploited marine habitats in the world. They face pressures from habitat degradation and pollution from terrestrial runoff and fisheries pressures. These pressures have led to coastal shark population declines throughout the region (Dulvy et al., 2017). Until now, life history characteristic studies of the Australian blacknose shark have come from populations along the northern regions of Australia and the Great Barrier Reef. While populations in Papua New Guinea have been vastly underrepresented. This study utilized by-catch data to investigate the age, growth rates, and maturity of the Australian blacknose shark in the Gulf of Papua in New Guinea and compare them to the populations within Australia. Previous studies of the northern Australian populations revealed a maximum length of 34 inches (88 cm) with a maximum age of 6.5 years. The study of the New Guinea population revealed a population that was slightly smaller at 31 inches (79 cm) but reached a maximum of 10.5 years (Baje et al., 2019). These differences were present despite similar sizes at birth. While the Australian blacknose shark is currently categorized as Least Concern by the International Union for the Conservation of Nature (IUCN), it is important to determine life history characteristics for subpopulations to establish sustainable management policies (Baje, 2019). This recent study takes the first initiative to protecting a population that has so far gone unstudied.
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!
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Featured Image Source
CSIRO National Fish Collection (Photographer). (2016). Carcharhinus coatesi [Digital Image]. Retrieved from https://commons.wikimedia.org/wiki/File:Carcharhinus_coatesi_csiro.jpg
Baje, L. (2019). Carcharhinus coatesi. The IUCN Red List of Threatened Species. Retrieved from https://www.iucnredlist.org/species/70679787/70680049
Baje, L., Smart, J. J., Grant, M. I., Chin, A., White, W. T., & Simpfendorfer, C. A. (2019). Age, growth and maturity of the Australian blackspot shark (Carcharhinus coatesi) in the Gulf of Papua. Pacific Conservation Biology.
Dulvy, N. K., Simpfendorfer, C. A., Davidson, L. N., Fordham, S. V., Bräutigam, A., Sant, G., & Welch, D. J. (2017). Challenges and priorities in shark and ray conservation. Current Biology, 27(11), R565-R572.
Ebert, D. A., Fowler, S. L., & Dando, M. (2015). Sharks of the world: a fully illustrated guide. Wild Nature Press.
Taylor, S. M., Harry, A. V., & Bennett, M. B. (2016). Living on the edge: latitudinal variations in the reproductive biology of two coastal species of sharks. Journal of fish biology, 89(5), 2399-2418.