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Home , Himantura, Porcupine ray, Reticulate whipray, Urogymnus

Journal and Proceedings of the Royal Society of New South Wales, vol. 146, nos. 447 & 448, p. 64-66. ISSN 0035-9173/13/010064-3

Thesis abstract

The ecology and biology of stingrays (Dasyatidae) at Ningaloo Reef, Western

Owen R. O’Shea

Abstract of a thesis for a Doctorate of Philosophy submitted to Murdoch University, Perth, Australia

Batoids make up a significant portion of is an endpoint. Safe and humane the biomass in coastal and nearshore techniques were developed as part of this ecosystems, yet few data are available on study in order to sample the rays required the functional role and life history using lethal methods. These techniques characteristics of rays in these proved successful with both considerations environments. Given their conservative life met and it is hoped, will provide a history traits and vulnerability to extrinsic framework for safe practices for any future pressures, urgent information is required to work where lethal sampling of large, further understand this little known group potentially hazardous demersal of fishes. The objectives of this research elasmobranchs is required (O’Shea et al. were to assess the biological and ecological 2013). characteristics of tropical stingrays at Ningaloo Reef, Western Australia. More Age and growth parameter estimates were specifically, I wanted to quantify the evaluated for these five by physical and biological impacts associated sectioning and counting calcium band-pair with by stingrays, prey specificity deposition in vertebral samples. Due to and trophic resource partitioning and age less than ideal sample sizes on account of and growth of five sympatric species: blue- logistical constraints, a multi-analytical spotted mask Neotrygon kuhlii (Müller & approach was adopted to optimise Henle 1841), cowtail Pastinachus atrus parameter estimates and generate realistic (Macleay 1883), blue-spotted fantail results. This included using a Bayesian Taeniura lymma (Forsskål 1775), porcupine framework to approximate the posterior asperrimus, (Bloch & Schneider distribution of the growth parameters. 1801) rays and the Growth rates of smaller-bodied species uarnak (Forsskål 1775). were faster than for larger-bodied species, but longevity was shorter. The oldest A technical assessment for safe and ethical recorded age for these rays was 27 years lethal sampling protocols for large dasyatid and although validation was not possible, rays is discussed as a foundation to this annual deposition is assumed based on research. Strict codes of practice for the previous accounts of similar species. This welfare of in scientific research is the first time that growth parameter demand up to date methodologies for estimates in dasyatid rays have been ethical consideration, especially where death assessed using this approach, yet the

64 JOURNAL AND PROCEEDINGS OF THE ROYAL SOCIETY OF NEW SOUTH WALES O’Shea – Ecology and Biology of Stingrays on Ningaloo Reef application is highly relevant for other rare, A methods paper is also included in this vulnerable or endangered species where thesis detailing a cost-effective method of optimal sample sizes may not be possible tag attachment and retrieval for short-term (O’Shea et al. in review). tracking in reef associated elasmobranchs. Field-testing of galvanic timed releases and The characterisation of ray diets was the practical application in tagging two assessed through stomach content analysis individual black tip reef sharks (Carcharhinus from 170 individuals of these five species. melanopterus), two large cowtail stingrays Five broad taxonomic prey categories were (Pastinachus atrus and a single common to all species of ray; however, H. Urogymnus asperrimus) are discussed. uarnak is shown to be a specialist Preliminary results of these short-term while the remaining four species showed tracks demonstrated that these methods are high levels of overlap within their diets a rapid and effective means of tagging (O’Shea et al. 2013). Assessment of the elasmobranchs with limited impact on the physical impacts related to foraging ’s welfare (Speed et al. 2013). within an intertidal embayment, previously identified as an area of intense feeding by This research is the first of its kind at rays, demonstrated high levels of sediment Ningaloo Reef and details critical functional excavation. As a direct result of processes and highlights the ecological bioturbation by stingrays over 21 days, 760 significance of rays within reef kg of sediment was excavated from an environments. It also details current experimental area of 1,500 m2 (O’Shea et al. methodologies and techniques trialled for 2012). Predation effects by rays were the first time within the context of examined by experimentally manipulating ecological studies on tropical densities in fixed areas to prevent feeding. elasmobranchs. Data presented here can Results indicated that some, but not all be used to develop or contribute to, prey-taxa differed significantly in conservation and management strategies abundance between treatment and controls. for this overlooked, yet vulnerable group of Sampling also allowed a quantitative fishes. assessment of infaunal taxa common within the Marine Park, and the potential References: importance as a prey source for rays, as well O’Shea, O.R. (2010) New locality record for the as other epibenthic predators. parasitic leech Pterobdella amara, and two new host stingrays at Ningaloo Reef, Western Throughout the course of this study, a new Australia. Marine Biodiversity Records 3 e113 species locality record and parasite-host O’Shea, O.R., Thums, M., van Keulen, M. and relationships was described for the parasitic Meekan, M. (2012) Bioturbation by stingray at leech Pterobdella amara and Himantura Ningaloo Reef, Western Australia. Marine and leoparda and Urogymnus asperrimus. This is the Freshwater Research 63:(3), 189-197 first time this leech has been encountered in Western Australia and in combination Speed, C.W., O’Shea, O.R. and Meekan, M.G. with a significant gnathiid isopod larvae (2013). Transmitter attachment and release infestation; the effects on an individual methods for short-term shark and stingray stingray are documented (O’Shea 2010). tracking on coral reefs. Marine Biology DOI 10.1007/s00227-012-2151-y

65 JOURNAL AND PROCEEDINGS OF THE ROYAL SOCIETY OF NEW SOUTH WALES O’Shea – Ecology and Biology of Stingrays on Ningaloo Reef O’Shea, O.R, Thums, M., van Keulen, M., sample species: an example for tropical Kempster, R. and Meekan, MG. (2013). Dietary stingrays. PLoS One niche overlap of five sympatric stingrays (Dasyatidae) at Ningaloo Reef, Western Australia. Journal of Fish Biology 82:(6), 1805-1820 Dr Owen R. O’Shea, School of Biological Science and O’Shea, O.R., Meekan, M. and van Keulen, M. Biotechnology, (2013). Lethal sampling of stingrays (Dasyatidae) Murdoch University, for research. Proceedings of the Australian and New Zealand Council for the Care of Animals in Research Perth, Western Australia, 6030 and Teaching. Annual Conference on Thinking AUSTRALIA outside the Cage: A Different Point of View. Perth, Western Australia, 24th – 26th July 2012 E-mail: [email protected]

O’Shea, O.R., Braccini, M., McAuley, R., Speed, C. and Meekan, M. (In review). Optimising the estimation of growth parameters of difficult-to-

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