title: Partial migration: growth varies between resident and migratory fish.
abstract: Partial migration occurs in many taxa and ecosystems and may confer survival benefits. Here, we use otolith chemistry data to determine whether fish from a large estuarine system were resident or migratory, and then examine whether contingents display differences in modelled growth based on changes in width of otolith growth increments. Sixty-three per cent of fish were resident based on Ba : Ca of otoliths, with the remainder categorized as migratory, with both contingents distributed across most age/size classes and both sexes, suggesting population-level bet hedging. Migrant fish were in slightly better condition than resident fish based on Fulton's K condition index. Migration type (resident versus migratory) was 56 times more likely to explain variation in growth than a model just incorporating year- and age-related growth trends. While average growth only varied slightly between resident and migratory fish, year-to-year variation was significant. Such dynamism in growth rates likely drives persistence of both life-history types. The complex relationships in growth between contingents suggest that management of species exhibiting partial migration is challenging, especially in a world subject to a changing climate.
authors: Southern Seas Ecology Laboratories, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia bronwyn.gillanders@adelaide.edu.au.
authors: Bronwyn M
authors: BM
authors: Gillanders
authors: Southern Seas Ecology Laboratories, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors: Christopher
authors: C
authors: Izzo
authors: Southern Seas Ecology Laboratories, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia.
authors: Zoë A
authors: ZA
authors: Doubleday
authors: South Australian Research Development Institute Aquatic Sciences, Adelaide, West Beach, South Australia 5024, Australia.
authors: Qifeng
authors: Q
authors: Ye
mesh_terms: D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D001315:Australia; D063366:Estuaries; D005260:Female; D008297:Male; D010037:Otolithic Membrane / Q000737:chemistry*; D010473:Perciformes / Q000254:growth & development* / Q000502:physiology; D054712:Salinity
keywords: fish; migration; otolith chemistry; otolith growth; partial migration; residency