Morphology, sex ratio and cause of death in Australian sea lion (Neophoca cinerea) pups
Rebecca R. McIntosh A C and Clarence W. Kennedy B
+ Author Affiliations
- Author Affiliations
A Zoology Department, La Trobe University, Bundoora, Vic. 3086, Australia.
B Department for Environment and Natural Resources, Kingscote, SA 5223, Australia.
C Corresponding author. Email: r.mcintosh0@gmail.com
Australian Mammalogy 35(1) 93-100 https://doi.org/10.1071/AM12037
Submitted: 4 July 2012 Accepted: 21 July 2012 Published: 4 February 2013
Abstract
During a study of the demographics of the Australian sea lion (Neophoca cinerea), the sex ratio and morphology were obtained from 128 pups at Seal Bay Conservation Park over three breeding seasons (2002–03, 2004 and 2005–06). Gross necropsies were also performed. Dead pups were small and young, averaging 8.0 and 7.0 kg in weight, and 75.2 and 71.3 cm in length, for males and females respectively, only 1.8 kg heavier and 6.7 cm longer than newborn pups. There was no sex bias in the dead pups overall or in each cause of death classification. In 49% of mortalities, cause of death could not be inferred from gross necropsy and pups appeared in good condition. In pups in which cause of death was inferred, trauma inflicted by conspecifics was the primary result in both males and females (31.6%), followed by emaciation (10.4%), stillbirth or premature birth (7.6%) and possible shark attack (1.4%). Histopathological examination of tissues and other investigations would be required to determine whether other factors, such as disease or parasitic infection, and pollutant contamination contribute to pup mortality.
Additional keywords: Conspecific aggression, necropsy, otariid, pup mortality, trauma.
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