Standard Talk (15 mins) Australian Society for Fish Biology Conference 2022

Rapid warming, regional climate and fishing all drive fish growth variation in SE Australian waters (#5)

John R Morrongiello 1
  1. University of Melbourne, Parkville, VIC, Australia

South-east Australian waters support both unique biodiversity and major commercial fisheries, but the region and its natural resources are increasingly being exposed to rapid oceanic warming. Here, I present the results of a large-scale project investigating the environmental drivers of fish growth variation using a data set of unprecedented spatial, temporal, and biological coverage. Otolith-based growth time series for over 30 species and stocks, each up to 100 years in length, from across nearly 3000km of coastal SE Australia and a range of habitats were analysed using dynamic factor analysis and generalised additive models. Long-term growth patterns for many species displayed strong temporal synchrony, pointing to universal ecosystem drivers of change. Directional trends in modes of growth variation were indicative of ubiquitous warming impacts (via direct and/or indirect pathways) that either promoted or inhibited growth depending on a species’ habitat and distributional range. Quasi decadal oscillations in observed growth rates reemphasised the importance of Zonal Westerly Winds and the Southern Annular Mode in driving regional recruitment and system productivity variation. Overall, growth variation was also sensitive to regional fishing effort. This finding corroborates other work in identifying the larger-scale impacts of fishing on fish assemblages. Together, our work highlights the valuable information stored within otoliths and their potential to provide unprecedented levels of spatial and temporal resolution into the drivers of productivity change in our oceans.