Resolving the early life history of King George whiting (Sillaginodes punctatus: Perciformes) using otolith microstructure and trace element chemistry
2019
Rogers, Troy A. | Fowler, Anthony J. | Steer, Michael A. | Gillanders, Bronwyn M.
Understanding the early life history processes of fish that lead to recruitment is critical for understanding population dynamics. This study explored the early life history of King George whiting (Sillaginodes punctatus) that recruited to an important nursery area in South Australia in 2016 and 2017. The early life history was reconstructed based on the retrospective analysis of otolith microstructure and chemistry for settlement-stage larvae collected fortnightly from July to November. These fish hatched between March and July, but a 3-week period in May led to 52–71% of recruitment. Recruits from successive sampling occasions differed in age, size and growth rate, potentially related to seasonal changes in water temperature and larval food availability. During both years, there were significant changes in otolith elemental chemistry among the groups of recruits that primarily related to changes in Sr:Ca. There are two hypotheses to account for the differences in otolith chemistry: either (1) a single, primary spawning source and within-season environmental change; or (2) multiple spawning sources. Further investigation with oceanographic models of larval dispersal will help differentiate between these. The retrospective analysis of otoliths has improved the understanding of early life history for this important species, with implications for fishery management.
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