Modelling the spatial distribution of Patagonian toothfish (Dissostichus eleginoides) by length and age around Heard Island and McDonald Islands on the Kerguelen Plateau

Over 27 000 fish caught around Heard Island and McDonald Islands (HIMI) on the Kerguelen Plateau have been aged from sectioned otoliths in the Australian ageing program since 1999, comprising more than 47 000 individual reads from seven different readers. Extensive length and age data for Patagonian toothfish (Dissostichus eleginoides) in particular can be used for large-scale spatial analyses across this region. In this paper we present spatial models of median toothfish length and age across the Australian exclusive economic zone (EEZ) at HIMI. Both models revealed strong patterns in the spatial distribution of toothfish, particularly in the concentration of smaller and younger fish on the shallower parts of the plateau (<500 m), and the occurrence of fish with increasing size and age in deeper water. These spatial analyses will aid in the further refinement of hypotheses regarding the habitat use and movement of different life history stages of toothfish in order to support appropriate management strategies for the species.