DOI: 10.5061/dryad.2fqz612v0
title: Data from: Ageing of juvenile coral grouper (Plectropomus maculatus) reveals year-round spawning and recruitment: Implications for seasonal closures

description: 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 optimising 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 1,002 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 maximise the recruitment contribution
 from periods of greatest reproductive success.
description: Harrison HB, Drane L, Berumen ML, Cresswell BJ, Evans RD,
 Galbraith GF, Srinivasan M, Taylor BM, Williamson DH, Jones GP. 2023
 Ageing of juvenile coral grouper (Plectropomus maculatus) reveals
 year-round spawning and recruitment: implications for seasonal closures.
 Proc Roy Soc B. <strong>Otolith preparation and
 age determination</strong> The sagittal otoliths
 were extracted from a subset of individuals from each collection period
 (Table S1) to estimate age and age-length relationships of juvenile
 <em>P. maculatus</em>. The preparation of otoliths followed
 the methods described in (Taylor et al 2016) and is consistent with
 previous studies of early life history growth in <em>P.
 maculatus</em> from the southern GBR (Mannering et al. 2008;
 Harrison et al. 2012, 2020; Williamson et al. 2016). Briefly, one otolith
 from each juvenile fish was affixed to a glass microscope slide using
 thermoplastic glue (Crystalbond 509), with the primordium (nucleus) on the
 inside edge of the slide and sulcus ridge perpendicular to the slide edge
 to obtain a transverse section of the sagittal otolith. Each otolith was
 ground to the edge of the slide using a GEMMASTA lapping wheel with a 1200
 grit diamond sanding wheel. The otoliths were then removed and affixed to
 a clean labelled slide, with the ground surface down, and polished using
 the same grit to a thin (≃150 μm) transverse section that intercepts the
 nucleus. Successive polishing was then carried out with 9, 3, and 0.3
 micron lapping film until daily growth increments were of optimal clarity.
 Sectioned otoliths were then coated in immersion oil and photographed
 under 200x and 400x magnification. Taylor BM, Gourley
 J, Trianni MS. 2016 Age, growth, reproductive biology and spawning
 periodicity of the forktail rabbitfish (Siganus argenteus) from the
 Mariana Islands. Mar Freshw Res 68, 1088–1097.
 (doi:10.1071/MF16169) Harrison HB, Bode M, Williamson
 DH, Berumen ML, Jones GP. 2020 A connectivity portfolio effect stabilizes
 marine reserve performance. Proceedings of the National Academy of
 Sciences 117, 25595–25600. (doi:10.1073/pnas.1920580117)
 Mannering TD, Jones G. 2008 Benefits of marine protected areas
 beyond boundaries: an evaluation for two coral reef fishes. MSc, James
 Cook University, Townsville. Williamson DH et al. 2016
 Large-scale, multidirectional larval connectivity among coral reef fish
 populations in the Great Barrier Reef Marine Park. Mol Ecol 25, 6039–6054.
 (doi:10.1111/mec.13908)
description: Please see the README document ("README.md") and the
 accompanying published article: Harrison HB, Drane L, Berumen ML,
 Cresswell BJ, Evans RD, Galbraith GF, Srinivasan M, Taylor BM, Williamson
 DH, Jones GP. 2023 Data from Ageing of juvenile coral grouper
 (<em>Plectropomus maculatus</em>) reveals year-round spawning
 and recruitment: implications for seasonal closures. Proc Roy Soc B,
 Accepted DOI: https://doi.org/10.1098/rspb.2023.0584