ESR 9:67-79 (2009)  -  DOI:

Age-based demography of humpback grouper Cromileptes altivelis: implications for fisheries management and conservation

Ashley J. Williams1,7,*, Campbell R. Davies2, Bruce D. Mapstone3, Leanne M. Currey1, David J. Welch1,4, Gavin A. Begg5, Aaron C. Ballagh1, J. Howard Choat6, Cameron D. Murchie1, Colin A. Simpfendorfer1

1Fishing and Fisheries Research Centre, School of Earth and Environmental Science, James Cook University, Queensland 4811, Australia
2CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart,Tasmania 7001, Australia
3Centre for Australian Weather & Climate Research, a partnership between CSIRO and the Australian Bureau of Meteorology, GPO Box 1538, Hobart, Tasmania 7001, Australia
4Queensland Primary Industries and Fisheries, Department of Employment, Economic Development and Innovation, PO Box 1085, Oonoonba, Queensland 4811, Australia
5Bureau of Rural Sciences, Department of Agriculture, Fisheries and Forestry, GPO Box 858, Canberra, ACT 2601, Australia
6School of Marine and Tropical Biology, James Cook University, Queensland 4811, Australia
7Present address: Oceanic Fisheries Programme, Secretariat of the Pacific Community, BP D5, 98848 Noumea, New Caledonia

ABSTRACT: The humpback grouper Cromileptes altivelis is listed as Vulnerable on the IUCN Red List because of concerns about unsustainable levels of harvest. Quantitative estimates of life history parameters are scarce, limiting formal assessment of long-term harvest rates and conservation risk and the design of robust management measures. We provide the first estimates of age-based population parameters for C. altivelis, using samples from the Great Barrier Reef (GBR) and Torres Strait, Australia. Population parameters did not differ significantly between regions. The maximum observed age was 19 yr, the von Bertalanffy growth parameters were K = 0.30 yr–1, L = 597 mm, and total mortality rate, estimated from an age-based catch curve, was 0.26 yr–1. Preliminary estimates of natural mortality for the GBR, based on samples from reefs closed to fishing, were 0.23 yr–1 (Hoenig regression) and 0.26 yr–1 (catch curve), suggesting recent fishing mortality was low. C. altivelis was found to be a protogynous hermaphrodite with 50% of individuals being male at length 547 mm and age 9.6 yr. Peak spawning was between October and January. These results contrast with previous perceptions of life history traits of this species and suggest that C. altivelis may not be as vulnerable to managed fishing pressure as previously thought. Notwithstanding this, there remains considerable uncertainty in unfished abundance and average recruitment levels for C. altivelis populations. We consider a combination of management strategies including size limits, effort controls and no-take areas that are likely to be most effective in minimising the conservation risk for C. altivelis populations and provide sustainable yields across the species’ range.

KEY WORDS: Humpback grouper · Cromileptes altivelis · Conservation · Fisheries management · Age-based demography · Great Barrier Reef · Torres Strait · Coral reef

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Cite this article as: Williams AJ, Davies CR, Mapstone BD, Currey LM and others (2009) Age-based demography of humpback grouper Cromileptes altivelis: implications for fisheries management and conservation. Endang Species Res 9:67-79.

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