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Adult sex ratios (ASRs) and population size are two of the most fundamental parameters in population biology, as they are the main determinants of genetic and demographic viability, and vulnerability of a population to stochastic events. Underpinning the application of population viability analysis for predicting the extinction risk of populations is the need to accurately estimate parameters that determine the viability of populations (i.e. the ASR and population size). Here we demonstrate that a lack of temporal information can confound estimation of both parameters. Using acoustic telemetry, we compared differences in breeding durations of both sexes for a giant Australian cuttlefish Sepia apama breeding aggregation to the strongly male-biased operational sex ratio (4:1), in order to estimate the population ASR. The ratio of breeding durations between sexes was equal to the operational sex ratio, suggesting that the ASR is not strongly male-biased, but balanced. Furthermore, the short residence times of individuals at the breeding aggregation suggests that previous density-based abundance estimates have significantly underestimated population size. With the current wide application of population viability analysis for predicting the extinction risk of populations, tools to improve the accuracy of such predictions are vital. Here we provide a new approach to estimating the fundamental ASR parameter, and call for temporal considerations when estimating population size.

Item Type:	Refereed Article
Keywords:	Acoustic telemetry Breeding aggregation Operational sex ratio Sepia apama Viability analysis
Research Division:	Agricultural, Veterinary and Food Sciences
Research Group:	Fisheries sciences
Research Field:	Fisheries sciences not elsewhere classified
Objective Division:	Environmental Management
Objective Group:	Coastal and estuarine systems and management
Objective Field:	Coastal or estuarine biodiversity
UTAS Author:	Semmens, JM (Professor Jayson Semmens)
ID Code:	72015
Year Published:	2011
Web of Science® Times Cited:	14
Deposited By:	Sustainable Marine Research Collaboration
Deposited On:	2011-08-18
Last Modified:	2012-04-05
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