Vital demographic statistics and management of the baldchin groper (Choerodon rubescens) from the Houtman Abrolhos Islands
Kim Nardi A B D , Stephen J. Newman A , Michael J. Moran A and Geoffrey P. Jones CA Western Australian Fisheries and Marine Research Laboratories, Department of Fisheries, Government of Western Australia, PO Box 20, North Beach, WA 6920, Australia.
B Present address: Department of Fisheries, Government of Western Australia, 69–75 Connell Road, Geraldton, WA 6530, Australia.
C School of Marine Biology and Aquaculture, James Cook University of North Queensland, Townsville, Qld 4811, Australia.
D Corresponding author. Email: knardi@fish.wa.gov.au
Marine and Freshwater Research 57(5) 485-496 https://doi.org/10.1071/MF05187
Submitted: 19 September 2005 Accepted: 6 April 2006 Published: 29 June 2006
Abstract
In order to evaluate appropriate management strategies, the life history and demography of the baldchin groper (Choerodon rubescens) was examined from speared samples and commercial catches at the Houtman Abrolhos Islands, Western Australia. Ages were estimated from sections of sagittal otoliths, validated by oxytetracycline labelling of fish recaptured after a minimum of 12 months at liberty. Male C. rubescens (n = 147; 373–639 mm) ranged from ages 5 to 20 years, and females (n = 354; 226–610 mm) ranged from 2 to 13 years. The population underwent a transition in dominance from females to males at age 11–12 years and 500–550 mm total length. Gonad development was seasonal and spawning was evident from spring to summer (September–January), with evidence of aggregation behaviour. Indirect estimates of the annual instantaneous rate of natural mortality (M) ranged from 0.05 to 0.58 and total mortality (Z), ranged from 0.21 to 0.56, rendering stock assessment highly uncertain. The limited geographic range, slow growth, long potential life span, protogynous sex change, aggregative spawning and high discard mortality rates render C. rubescens susceptible to overfishing. In order to manage this mobile species successfully, marine protected areas must continue to be supplemented by strict catch controls in fished areas.
Extra keywords: age, age validation, growth, mortality, reproduction, sectioned otoliths.
Acknowledgments
This paper is dedicated to the memory of the late Colin Chalmers, Manager of the Fish and Fish Habitat Protection Program of the Department of Fisheries (Government of Western Australia), an active supporter of all aspects of this project. The authors gratefully acknowledge the funding and logistical support provided by the Department of Fisheries, Government of Western Australia. We would like to sincerely thank all the willing volunteers who helped dissect numerous fish at the fish markets or at the Abrolhos Islands, in particular, Nicole Horsman, Jackie Sauvage, Rod O’Halloran, Chris Dibden, Richard Sellers, Dr Lindsay Joll and Clinton Syers. The authors are thankful to the Geraldton fish processors and numerous professional fishermen who allowed us access to fish caught at the Abrolhos Islands in order to process samples. Technical assistance provided by Dr Michael Mackie and Lisa Farrington was appreciated. Constructive comments on the draft manuscript provided by our colleagues are greatly appreciated.
Adreani, M. S. , Erisman, B. E. , and Warner, R. R. (2004). Courtship and spawning behaviour in the California sheephead, Semicossyphus pulcher (Pisces: Labridae). Environmental Biology of Fishes 71, 13–19.
| Crossref | GoogleScholarGoogle Scholar |
Beamish, R. J. , and Fournier, D. A. (1981). A method for comparing the precision of a set of age determinations. Canadian Journal of Fisheries and Aquatic Sciences 38, 982–983.
Choat, J. H. , Davies, C. R. , Ackerman, J. L. , and Mapstone, B. D. (in press). Age structure and growth in a large teleost, Cheilinus undulatus with a review of size distribution in labrid fishes. Marine Ecology Progress Series. ,
Hilborn, R. , Branch, T. A. , Ernst, B. , Magnussson, A. , Minte-Vera, C. V. , Scheuerell, M. D. , and Valero, J. L. (2003). State of the world’s fisheries. Annual Review of Environment and Resources 28, 359–399.
| Crossref | GoogleScholarGoogle Scholar |
Nardi, K. , Jones, G. P. , Moran, M. J. , and Cheng, Y. W. (2004). Contrasting effects of marine protected areas on the abundance of two exploited reef fishes at the sub-tropical Houtman Abrolhos Islands, Western Australia. Environmental Conservation 31, 160–168.
| Crossref | GoogleScholarGoogle Scholar |
Platten, J. R. , Tibbetts, I. R. , and Sheaves, M. J. (2002). The influence of increased line-fishing mortality on the sex ratio and age of sex reversal of the venus tuskfish. Journal of Fish Biology 60, 301–318.
| Crossref | GoogleScholarGoogle Scholar |
Roberts, C. M. , Hawkins, J. P. , and Gell, F. R. (2005). The role of marine reserves in achieving sustainable fisheries. Philosophical Transactions of the Royal Society of London. Series B 360, 123–132.
| Crossref | GoogleScholarGoogle Scholar |
Smith, C. L. (1967). Contribution to the theory of hermaphroditism. Journal of Theoretical Biology 17, 76–90.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Tegner, M. J. , and Dayton, P. K. (2000). Ecosystem effects of fishing in kelp forest communities. ICES Journal of Marine Science 57, 579–589.
| Crossref | GoogleScholarGoogle Scholar |
van Herwerden, L. , Choat, J.H. , Dudgeon, C.L. , Carlos, G. , Newman, S.J. , Frisch, A. , and van Oppen, M. (in press). Contrasting patterns of genetic structure in two species of the coral trout Plectropomus (Serranidae) from east and west Australia: introgressive hybridization or ancestral polymorphisms. Molecular Phylogenetics and Evolution. ,
| Crossref | GoogleScholarGoogle Scholar |
![](../../media/share/OpenURL_Image.gif)
Vetter, E. F. (1988). Estimation of natural mortality in fish stocks: a review. Fishery Bulletin 86, 25–43.
![](../../media/share/OpenURL_Image.gif)
Walker, M. H. (1983). Aspects of the life history of baldchin groper trapped at the Abrolhos Islands. FINS 16, 4–7.
![](../../media/share/OpenURL_Image.gif)
West, G. (1990). Methods of assessing ovarian development in fishes: a review. Australian Journal of Marine and Freshwater Research 41, 199–222.
| Crossref | GoogleScholarGoogle Scholar |
![](../../media/share/OpenURL_Image.gif)