Stable isotopes reveal post-release trophodynamic and ontogenetic changes in a released finfish, mulloway (Argyrosomus japonicus)

Matthew D. Taylor, Debashish Mazumder

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Carbon and nitrogen stable isotope ratios were analysed for hatchery-reared, recaptured and wild mulloway, Argyrosomus japonicus, to investigate temporal and growth-related changes in isotopic composition for stocked fish after release, and to evaluate changes in isotopic composition in terms of ontogenetic dietary switches. δ13C and δ15N values decreased and increased, respectively, after release. The isotope composition of released fish was distinct from wild fish until 200 days after release, but after 200 days post-release fish did not differ significantly from wild fish of similar or greater sizes. Abrupt dietary transitions from crustaceans to teleost fish (>50 cm total length (TL)) were evident in a rapid δ13C and δ15N change in wild mulloway, and δ15N was significantly greater in wild fish >65 cm TL compared with wild fish <50 cm TL. Multivariate carbon and nitrogen isotopic data were suitable for separating stocked and wild fish for up to 200 days after release, but did not separate wild fish grouped according to dietary composition. Carbon and nitrogen isotopic composition closely reflected dietary transitions and rapid adaptation by stocked mulloway to wild diets, which was evident in a high tissue turnover rate of up to 0.017 day -1. Stable isotopes are a useful tool for examining the integration of released fish into stocked ecosystems and can be used to describe convergence in the diets of wild and released fish.

Original languageEnglish
Pages (from-to)302-308
Number of pages7
JournalMarine and Freshwater Research
Volume61
Issue number3
DOIs
Publication statusPublished - 2010
Externally publishedYes

Keywords

  • Back calculation
  • Diet
  • Ontogeny
  • Otolith growth
  • Sciaenidae

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