Ageing of juvenile coral grouper (Plectropomus maculatus) reveals year-round spawning and recruitment: Implications for seasonal closures

H. B. Harrison*, L. Drane, M. L. Berumen, B. J. Cresswell, R. D. Evans, G. F. Galbraith, M. Srinivasan, B. M. Taylor, D. H. Williamson, G. P. Jones

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Temporal patterns in spawning and juvenile recruitment can have major effects on population size and the demographic structure of coral reef fishes. For harvested species, these patterns are crucial in determining stock size and optimizing management strategies such as seasonal closures. For the commercially important coral grouper (Plectropomus spp.) on the Great Barrier Reef, histological studies indicate peak spawning around the summer new moons. Here we examine the timing of spawning activity for P. maculatus in the southern Great Barrier Reef by deriving age in days for 761 juvenile fish collected between 2007 and 2022, and back-calculating settlement and spawning dates. Age-length relationships were used to estimate spawning and settlement times for a further 1002 juveniles collected over this period. Unexpectedly, our findings indicate year-round spawning activity generates distinct recruitment cohorts that span several weeks to months. Peak spawning varied between years with no clear association with environmental cues, and little to no alignment with existing seasonal fisheries closures around the new moon. Given the variability and uncertainty in peak spawning times, this fishery may benefit from additional and longer seasonal closures, or alternative fisheries management strategies, to maximize the recruitment contribution from periods of greatest reproductive success.

Original languageEnglish (US)
Article number20230584
JournalProceedings of the Royal Society B: Biological Sciences
Issue number2001
StatePublished - Jun 28 2023


  • age-based demography
  • coral reef fisheries
  • reproductive ecology
  • seasonal fishing closures

ASJC Scopus subject areas

  • General Immunology and Microbiology
  • General Biochemistry, Genetics and Molecular Biology
  • General Environmental Science
  • General Agricultural and Biological Sciences


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