Synchrony and variation across latitudinal gradients: The role of climate and oceanographic processes in the growth of a herbivorous fish Jerom R. Stocks a,b, ⁎, Charles A. Gray a,d , Matthew D. Taylor a,c a School of Biological Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia b Batemans Bay Fisheries Centre, PO Box 17, Batemans Bay, NSW 2536, Australia c Wild Fisheries Research, Port Stephens Fisheries Institute, Locked Bag 1, Nelson Bay, NSW 2316, Australia d WildFish Research, Sydney, NSW 2232, Australia abstract article info Article history: Received 17 April 2013 Received in revised form 8 January 2014 Accepted 3 March 2014 Available online 12 March 2014 Keywords: Climate Girella elevata Growth Otolith Increments Sclerochronology Spatial and temporal variation in the growth of a widely distributed temperate marine herbivore, Girella elevata, was examined using length-at-age data and multi-decadal otolith increment growth chronologies. In total 927 G. elevata were collected from three regions of the Australian south-east coast, extending 780 km and covering the majority of the East Australian Current, a poleward-flowing western boundary current of the Southern Pacific Gyre and climate change hotspot. A validated ageing method using sectioned sagittal otoliths was developed to enumerate both daily (juvenile fish) and annual otolith increments. G. elevata exhibited great longevity with a maximum recorded age of 45+ yrs. Spatial variation in growth from length-at-age data was observed with the highest growth rates within the centre of the species distribution. Analysis of otolith growth chronologies of 33 yrs showed a positive relationship with the Southern Oscillation Index. Identifying links between life- history characteristics and variation in oceanographic conditions across latitudinal gradients may shed light on potential impacts of expected climate shifts on fish productivity. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Exploring latitudinal gradients of age and growth rates can provide insight into the relationship between the biological attributes of a spe- cies and variability in the environment in which it lives. Growth varia- tion may be a result of trade-offs among other life-history traits such as fitness and reproduction, including onset of maturity and fecundity (Vila-Gispert et al., 2002), or restrictions imposed by latitudinal gradi- ents in environmental conditions such as temperature (Lappalainen et al., 2008) and productivity (Sogard, 2011). For coastal and marine species, identifying links between oceanographic variability and latitu- dinal gradients in life history characteristics may shed light on expected changes associated with both basin- and decadal-scale climate shifts. In addition, such climate shifts may result in altered species distributions and community structures, which have already been observed in a number of fishes of south-eastern Australia (Last et al., 2011) and else- where throughout the world (Booth et al., 2011; Hiddink and Ter Hofstede, 2008; Perry et al., 2005). Sclerochronological approaches, primarily employing fish otoliths (earstones), are being increasingly used to examine long-term temporal trends in fish growth (Black, 2009; Godiksen et al., 2012; Morrongiello et al., 2010; Neuheimer et al., 2011; Thresher et al., 2007). Due to the indeterminate nature of otolith deposition, long-term otolith growth chronologies can be constructed to deduce life-history traits (Stocks et al., 2011) and reflect environmental conditions and climate change (Thresher et al., 2007). Multiple climate and oceanographic processes have been correlated to otolith increment chronologies, such as sea-surface temperature (SST) (Black et al., 2008), El Niño Southern Oscillation (ENSO) (Black et al., 2008), and localised upwelling (Boehlert et al., 1989). Girella elevata occur on shallow near-shore rocky reefs along the south-east coast of mainland Australia and north-eastern Tasmania, with their geographic distribution stretching across approximately 13° of latitude (Kuiter, 1993). The species is often found during the day in caves and under rocky ledges or in surge regions, although post- settlement fish use rockpools as nurseries before moving to shallow rocky reefs as they grow (Bell et al., 1980; Burchmore et al., 1985; Griffiths, 2003). The species experiences considerable pressure from recreational fishing, particularly spearfishing and anglers from rock platforms (Kingsford et al., 1991; Lincoln Smith et al., 1989). The broad latitudinal distribution of G. elevata spans a large proportion of the East Australian Current (EAC). The EAC is the poleward-flowing western boundary current of the Southern Pacific Gyre, extending from the Coral Sea into Tasmanian waters. The EAC is primarily composed as a current of eddies (Mata et al., 2006), and thus displays high oceano- graphic variability. The EAC is considered among the fastest changing Journal of Sea Research 90 (2014) 23–32 ⁎ Corresponding author at: School of Biological Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia. E-mail address: jerom.stocks@dpi.nsw.gov.au (J.R. Stocks). http://dx.doi.org/10.1016/j.seares.2014.03.002 1385-1101/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Journal of Sea Research journal homepage: www.elsevier.com/locate/seares