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Fishery Bulletin 119(2-3) 
B E nitidus—kK| 
8 E. nitidus—NSW 
§ T declivis—K\ 
T. declivis—NSW 
LBL 
TLL 
Tae 
[a 
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 
Year 
Figure 3 
(A) Number of common jack mackerel (Trachurus declivis) and redbait (Emmelichthys nitidus) measured 
for each birth year and (B) number of otolith increments for each calendar year by species and region. These 
numbers indicate growth chronologies for samples collected during 2014-2016 from waters off Kangaroo 
Island (KI) and New South Wales (NSW) in Australia. 
analyses, resulting in growth chronologies for the periods 
from 2005 through 2016 for common jack mackerel and 
from 2003 through 2015 for redbait. 
Growth analysis 
Estimates of von Bertalanffy growth parameters were 
significantly different between regions for both species 
(common jack mackerel: 77=310.46, P<0.001; redbait: 
77=65.90, P<0.001; Fig. 4), with fish from KI (Table 2) 
growing slower but having a higher asymptotic length 
than fish caught in NSW (Table 2). Differences in growth 
between regions began at about 3.5 years for common jack 
mackerel, with the resulting difference in L,, by age 13 
being 4 cm FL (Fig. 4A). In redbait, growth differences 
began at approximately the same age as common jack 
mackerel (3 years versus 3.5 years, respectively; Fig. 4B), 
but the resulting difference in L,, was smaller for redbait 
(1 cm FL; KI: L,.=249.52 cm FL [standard error (SE) 1.6]; 
NSW: L..=238.89 cm FL [SE 1.2]) than for common jack 
mackerel (4 cm FL; KI: L,.=299.40 cm FL [SE 2.5]; NSW: 
L.=259.79 cm FL [SE 1.3]). Otolith growth at age from 
the mixed-effects model indicates that common jack 
mackerel and redbait from KI had faster growth than 
individuals from NSW (Fig. 4, C and D). 
Intrinsic predictors of growth 
Overall, growth synchrony for all growth comparisons was 
low and varied between Year and YearClass. Common jack 
mackerel from both KI and NSW had greater growth syn- 
chrony within Year (0.94% and 3.50%, respectively) than 
within YearClass (0.08% and 0.12%, respectively). In con- 
trast, redbait growth synchrony was greater within Year- 
Class (1.40% and 1.00% for KI and NSW, respectively) than 
within Year (0.17% and 0.60%, respectively). 
The best random-effect structure was different for all 
models; they included FishID as a random effect and a 
