144 
—0.100 
Fishery Bulletin 119(2-3) 
(9.) enspesedu9a} adepNs-eas 
0.080 | B 
0.050 ; 
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 
Year 
16.5 16.6 16.7 168 16.9 170 171 172 173 174 175 176 177 178 179 18.0 
Sea-surface temperatrue (°C) 
Figure 6 
(A) Predicted temporal variation in otolith increment growth (solid line), relative to the long- 
term mean (gray dashed line) and to optimal local sea-surface temperature (black dashed line), 
and (B) sea-surface temperature predicted effects plot of otolith increment growth for common 
jack mackerel (Trachurus declivis) collected from waters off Kangaroo Island in Australia during 
2014-2016. Predicted interannual growth variation is based on estimates for the Year random 
effect (best linear unbiased predictors). In panel A, the shaded area indicates standard error of the 
mean. In panel B, the shaded area indicates the 95% confidence interval. 
Benthic species are more likely to be exposed to similar 
conditions and, therefore, have high growth synchrony 
among individuals, as seen in the growth synchrony of site- 
attached marine fishes, such as the tiger flathead (2.0-21.6%; 
Morrongiello and Thresher, 2015), and of sessile marine 
organisms, such as the Pacific geoduck (Panopea abrupta) 
(62-72%; Helser et al., 2012). In these cases, the minimal 
movement or lack thereof results in more consistent envi- 
ronmental conditions experienced across individuals, com- 
pared with the more variable and widespread movements 
of small pelagic fishes (Eiler and Bishop, 2016). In contrast, 
results of other studies in which the growth chronologies of 
small pelagic fishes were examined indicate synchrony in 
growth among individuals, and environmental effects on 
growth have been identified (Tanner et al., 2019). However, 
the species examined in other studies reside in shallow 
coastal waters (with depths of ~100 m); in contrast, the spe- 
cies investigated in our study occur at depths >100 m 
(Pullen and TDPIF, 1994; Welsford and Lyle, 2003; Tanner 
et al., 2019). As such, the low interclass correlation coeffi- 
cients observed in our study may be a result of the deeper 
pelagic habitat of common jack mackerel and redbait caus- 
ing less-defined increments compared with the habitat and 
increments obseved for other species (e.g., snapper or black 
bream) (Newman et al., 2000). 
The challenges in reading growth increments on otoliths 
of common jack mackerel and redbait might have resulted 
in less precise measurements and, therefore, in artificially 
reduced synchrony. In the absence of cross-dating, the 
likelihood of errors in growth increment dating increases, 
possibly dampening extrinsic signals in increment data 
(Black et al., 2016; Smoliriski et al., 2020). As a result, 
potential dating errors might have also contributed to the 
low synchrony observed (Smoliriski et al., 2020). 
Both species had higher growth synchrony off NSW 
than off KI. This finding may reflect the different oceanic 
processes of each region. The EAC originates in the Coral 
Sea and flows southward along the coast of NSW (Suthers 
et al., 2011). As the EAC separates from the coast, it forms 
a series of eddies (200-300 km in diameter) along the coast- 
line that can persist for up to a year, and these eddies con- 
stitute a vital process for the nutrient cycling and biological 
