Restoration of flow regimes to benefit native fish populations requires an empirical understanding of relationships between hydrology, life history and population dynamics. Golden perch is one of only a few native species in the southern Murray-Darling Basin whose reproduction and recruitment has been consistently related to flow. Consequently, golden perch spawning and recruitment constitute a common objective of environmental water allocations. Nevertheless, to measure response, and inform environmental water delivery, an explicit understanding of when and where fish originated is fundamental.

Microstructural and chemical analyses of fish otoliths provide powerful tools for determining the spatio-temporal provenance of fish. We demonstrate how these tools can be used to retrospectively elucidate the natal origin of cohorts of golden perch in the lower Murray and to determine the spawning date and origin of juvenile fish in relation to the delivery of an environmental water allocation.

Daily and annual growth increments in otolith microstructure and strontium isotope ratios indicated that golden perch larvae, young-of-year and adults in the lower River Murray were often not locally sourced, but rather, resulted from spawning that occurred over a broad period (October–January) in the Darling and potentially mid-Murray rivers. These data enable the explicit spatio-temporal association of golden perch spawning and recruitment with flow, including environmental water delivery. Ultimately, population dynamics of golden perch in the lower River Murray are driven by processes occurring at scales of 100s-1000s kilometres. To achieve positive outcomes for native fish, delivery of environmental water must consider recruitment dynamics at these scales.