Zischke and Griffiths: Stock assessment of Acanthocybium solandri in the Pacific Ocean 
415 
Fishing mortality (F) 
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Fishing mortality (F) 
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Fishing mortality (F) 
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Figure 4 
Mean estimates (solid line) and 95% confidence intervals (gray shaded area) of yield per recruit (Y/R) 
and spawning stock biomass per recruit (SSB/R) for wahoo (Acanthocybium solandri) in the southwest 
Pacific Ocean during 2008-2010: (A) Y/R and ( B ) SSB/R for a model scenario with constant natural 
mortality for all ages (scenario 1 [SI]; see Materials and methods section) and (C) Y/R and (D) SSB/R 
for a model scenario where natural mortality is 10-fold higher for juvenile fish than for adults (S2; see 
Materials and methods section). Arrows indicate current fishing mortality. Black squares represent 
target reference points of fishing mortality at which the slope of the Y/R curve is 10% of the slope at 
the origin in panels A and C and target reference points of fishing mortality at which the SSB/R is 40% 
of the SSB/R at F= 0 in panels B and D. Open circles represent limit reference points of fishing mortal- 
ity at which maximum Y/R is produced in panels A and C and reference points of fishing mortality at 
which the SSB/R is 25% of the SSB/R at F= 0 in panels in B and D. 
eters. The base scenario (SI), including variability in 
growth and maturity parameters, resulted in 95% con- 
fidence intervals of approximately 10% for both Y/R and 
SSB/R. Although recent research has provided the most 
reliable account of wahoo growth dynamics (Zischke et 
al., 2013b), further biological research is needed to vali- 
date the periodicity of growth increment formation to 
ensure that length-at-age relationships used in future 
assessments are reliable. Future assessment of wahoo 
stocks should prioritize research that provides regional 
estimates of growth parameters. Similar effects of vari- 
ability in age and growth have been shown for walleye 
pollock ( Gadus chalcogrammus ) in the eastern Bering 
Sea, where aging error has had little effect on estimates 
of growth and mortality but has produced sufficiently 
different results in a Y/R analysis conducted to infer 
overfishing (Lai and Gunderson, 1987). 
The iterative approach also allowed us to assess the 
impact of potential management changes on Y/R and 
SSB/R. For example, F current exceeded in 53% 
of iterations under the standard scenario (SI), but this 
percentage decreased to 27% when a slot limit in the 
recreational fishery was introduced (F3; Table 2). Over- 
all, fishery management scenarios (F1-F4) had little 
effect on the results of the per-recruit model because 
^current was already lower than 3 (and similar to 1) of 
