Eel commonly transition between distinct habitats through their lifetime, particularly in larval and juvenile life stages. Such transitions are essential as the environmental demands and predation pressures experienced by fishes change dramatically with increases in body size. Understanding the nature of habitat use, habitat connectivity and ontogenetic timing of habitat transitions is key to establishing management practices covering whole life histories for commercially, recreationally and ecologically significant species. Tracing migrations of larval and juvenile fishes in coastal habitats is extremely challenging. Fishes are too small for most conventional tagging approaches and the high natural mortality means large tagging programs are needed. Otolith reading and microchemistry is an attractive alternative for reconstructing high resolution movements, where fishes move across chemical gradients. Until recently otolith microchemistry has largely focused on discriminating between populations rather than exploring temporal trends within individual fish. This project will build on recent collaborative experimental, observational and theoretical work to develop new approaches to using otolith microchemistry to explore habitat transitions in marine fishes.