Reproductive Biology and Life-History Plasticity of the Yellowfin Snapper Lutjanus xanthopinnis in the Southern South China Sea.

Authors

Takaomi Arai, Iy Vonne Tan, Norhayati Ahmad

Published in

Ecology and evolution. Volume 16. Issue 8. Pages e74166. Epub Aug 09, 2026.

Abstract

Studying fish reproductive biology provides critical insights into population dynamics, supporting effective fisheries management and wildlife conservation. Although the yellowfin snapper Lutjanus xanthopinnis was recently identified as a new species, its reproductive traits across the southern South China Sea remain poorly understood. This study elucidated the reproductive biology of L. xanthopinnis off Borneo and Brunei Darussalam, including spawning seasonality, gonadal development, sex ratio and fecundity. A total of 385 specimens were examined monthly over a one-year period. The overall sex ratio was 1.16:1, indicating a stable regional equilibrium (Chi-square test, p > 0.05). Based on monthly fluctuations in the gonadosomatic index (GSI) and histological analysis, both sexes exhibited a prolonged, nearly year-round spawning pattern; females showed a distinct peak from October to August, while males remained mature year-round. The estimated total length at 50% maturity (L ₅₀) was nearly identical between the sexes (18.3 cm for females; 18.8 cm for males), which is generally smaller than in related Lutjanidae species. Total fecundity ranged from 8000 to 65,000 eggs and showed no significant correlation with maternal body size. Contrasting these findings with recent data from adjacent regional populations reveals remarkable intraspecific plasticity in the life-history strategies of L. xanthopinnis. Unlike neighbouring populations that exhibit monsoon-restricted spawning, pronounced intersexual size differences and male-biased sex ratios, the Brunei population adopts a balanced, continuous reproductive regime. These striking intraspecific variations demonstrate that localised environmental conditions and oceanographic regimes drive significant ecological and evolutionary adaptations in the life cycle of coral reef fishes, even within closely situated geographic regions.

PMID:
42572773
Bibliographic data and abstract were imported from PubMed on 10 Aug 2026.

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