Reproductive biology of the eastern shovelnose stingaree Trygonoptera imitata from south-eastern Australia
Fabian I. Trinnie A B D , Terence I. Walker B C , Paul L. Jones A and Laurie J. Laurenson AA School of Life and Environmental Sciences, Deakin University, Warrnambool, Vic. 3280, Australia.
B Marine and Freshwater Fisheries Research Institute, Fisheries Victoria, Department of Primary Industries, PO Box 114, Queenscliff, Vic. 3225, Australia.
C Department of Zoology, The University of Melbourne, Parkville, Vic. 3010, Australia.
D Corresponding author. Email: fabiantrinnie@hotmail.com
Marine and Freshwater Research 60(8) 845-860 https://doi.org/10.1071/MF08165
Submitted: 26 May 2008 Accepted: 16 February 2009 Published: 27 August 2009
Abstract
In applying a quantitative approach to the reproduction of Trygonoptera imitata, the present study contributes to understanding the wide diversity in the reproductive biology of the family Urolophidae and provides insights to help determine phylogenetic relationships. This localised species is taken as bycatch in several inshore fisheries and potentially impacted by a range of other anthropogenic pressures, including introduced species, particularly in shallow-water pupping areas. T. imitata can be characterised as a species of comparatively low matrotrophic histotrophy with an extended period of relatively large eggs in utero (5–8 months) followed by rapid growth of the embryos (4–6 months). The reproductive cycle is annual with parturition occurring during late-February–April, followed immediately by ovulation. Mean size-at-birth is ~225 mm total length and there is a ~1000% gain in mean wet mass from egg (15 g) to full-term embryo in utero (150 g), the lowest reported for any viviparous batoid. Litter size increases with maternal length, reaching a maximum of seven, and sex ratio of embryos is 1 : 1. Maximum length and estimates of the maturity–ogive parameters l50 and l95 are similar for females and males.
Additional keywords: gestation, maternity, maturity, ovulation, reproduction.
Acknowledgements
Professional fishermen and technical staff, students and volunteers at the Marine and Freshwater Fisheries Research Institute (MAFFRI) and Victorian Marine Science Consortium are acknowledged for collection of specimens and Anne Gason of MAFFRI provided advice on statistical analyses and management of data. Finally, the constructive comments from the two anonymous reviewers are acknowledged. This project was funded by the Australian Fisheries Research and Development Corporation grant (FRDC 2002/003) and a Deakin University PhD scholarship.
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