Reproductive demography of a temperate protogynous and herbivorous fish, Odax pullus (Labridae, Odacini)
KAUST DepartmentRed Sea Research Center (RSRC)
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AbstractA common view is that, in marine fishes, herbivory and sex change are subject to physiological constraints at high latitudes, which are likely to affect growth rates and reproductive outputs. The present study examines the reproductive demography of Odax pullus, an herbivorous and protogynous species of temperate New Zealand. We establish an otolith-based methodology for age estimation and investigate sex-specific growth, longevity and age-based reproductive events. Individuals achieved a maximum age of 11 years, reached 85% of adult body size (455mm FL) within the first 3.5 years of life, were sexually mature by the age of 1.11.5 years and changed sex at 2.83.5 years, indicating fast simultaneous somatic and reproductive growth. There was no significant difference in growth or body size between the sexes. Ovary weight of spawning females increased significantly with size and age, suggesting the presence of size- and age-fecundity skews underlying the absence of sex change in larger and older females. Testes of reproductively active males comprised less than 1% of bodyweight, suggesting pair-spawning and little sperm competition. The present study provides metrics to support comparisons of the demography of this temperate protogynous and herbivorous labrid across spatial or temporal strata. © CSIRO 2011.
SponsorsWe thank Jethro Johnson, Brady Doak and Murray Birch for help with collection of samples; Benjamin Ruttenberg, Natalie Moltschaniwskyj, Ashley Williams and two anonymous reviewers for helpful comments of an earlier draft of the paper; and the Leigh Marine Laboratory for access to the Hawere research vessel. Samples were collected under New Zealand Ministry of Fisheries Permit 385, and the work was conducted under The University of Auckland Animal Ethics Committee Approval #AEC/03/2006/R456. The study and E.L.T. were supported by a Royal Society of New Zealand Marsden Fund grant to D.R., K.D.C. and J.H.C. E.L.T. was also supported by a University of Auckland International Fees Bursary, the University of Auckland's School of Biological Sciences, and the University of Auckland PBRF fund. D.R. was part-funded by the National Research Centre for Growth and Development, New Zealand.
JournalMarine and Freshwater Research