407 
NOAA 
National Marine 
Fisheries Service 
Fishery Bulletin 
established 1881 
Spencer F. Baird 
First U S, Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Per-recruit stock assessment of wahoo 
(Acanthocybium solandri) in the 
southwest Pacific Ocean 
Email address for contact author: mitchell.zischke@gmail.com 
1 School of Biological Sciences 
The University of Queensland 
Brisbane, Queensland 4072, Australia 
Present address: Purdue University 
Department of Forestry and Natural Resources 
195 Marsteller St 
West Lafayette, Indiana 47907, United States 
2 Oceans and Atmosphere Flagship 
Commonwealth Scientific and Industrial Research Organisation 
GPO Box 2583 
Dutton Park, Queensland 4102, Australia 
Abstract— A stock assessment incor- 
porating sensitivity in biological pa- 
rameters and potential fishery man- 
agement strategies for wahoo ( Acan- 
thocybium solandri) in the south- 
west Pacific Ocean was undertaken 
to assess the stock status of this 
species for 2008-2010. Selectivity 
probabilities at age were similar for 
2 commercial longline fisheries and 
a recreational sport fishery. How- 
ever, the median exploited length 
and age were slightly higher in the 
commercial fisheries than in the 
recreational fishery. Current fishing 
mortality (^current) was predicted to 
be lower than limit and target refer- 
ence points, with the exception that 
^current exceeded the target refer- 
ence point /'SSB40 (fishing mortality 
at which the spawning stock biomass 
per recruit [SSB/R] is 40% of the 
SSB/R at F= 0). This result indicates 
that wahoo may be at a greater risk 
of recruitment overfishing than of 
growth overfishing. Of the fishery 
management scenarios tested, intro- 
duction of a slot limit in the recre- 
ational fishery had the greatest ef- 
fect on assessment results; however, 
this effect was relatively minor and 
may not be practical to implement. 
Given the relatively short life span 
of wahoo, ongoing biological monitor- 
ing and rigorous collection of catch 
and effort data may facilitate contin- 
ued assessment of this species in the 
southwest Pacific Ocean. 
Manuscript submitted 20 March 2014. 
Manuscript accepted 21 July 2015. 
Fish. Bull. 113:407-418 (2015) 
Online publication date: 10 August 2015. 
doi: 10.7755/FB. 113.4.4 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Mitchell T. Zischke (contact author ) 12 
Shane P. Griffiths 2 
Wahoo ( Acanthocybium solandri) is 
a pelagic scombrid with a tropical 
and subtropical distribution in oce- 
anic waters worldwide (Collette and 
Nauen, 1983). This species is caught 
incidentally and retained as a by- 
product in commercial pelagic long- 
line, purse-seine, and trolling fisher- 
ies that target tunas and mackerels 
(Scombridae), broadbill swordfish 
(Xiphias gladius), and dolphinfishes 
(Coryphaena spp.) (Zischke, 2012). 
The average annual global catch 
of wahoo in these fisheries has re- 
mained around 3000 metric tons (t) 
since 1996 (Global Production Sta- 
tistics 1950-2012, FAO, available 
at website, accessed October 2012). 
Commercial catches in the Pacific 
Ocean have increased 10-fold over 
the past 15 years (Global Production 
Statistics 1950-2012, FAO) because 
of increases in effort in tuna fisheries 
in this region. Wahoo is also an im- 
portant target and nontarget species 
in subsistence and artisanal fisher- 
ies, as well as a prized catch in recre- 
ational fisheries throughout the west- 
ern Pacific Ocean (Zischke, 2012). 
Although catch and effort data from 
subsistence, artisanal, and recre- 
ational fisheries are scarce, evidence 
indicates that the recreational catch 
of wahoo may exceed the commercial 
catch off eastern Australia (Zischke 
et ah, 2012), as has been reported for 
the Atlantic Ocean (SAFMC 1 ). 
Off eastern Australia, wahoo are 
retained as byproduct in the Com- 
monwealth-managed Eastern Tuna 
and Billfish Fishery (ETBF). The 
ETBF is a pelagic longline fishery 
with a quota on species that include 
albacore ( Thunnus alalunga), yel- 
lowfin tuna (T. albacares ) and bigeye 
tuna (T. obesus), as well as broadbill 
1 SAFMC (South Atlantic Fishery Man- 
agement Council). 2003. Fishery 
management plan for the dolphin and 
wahoo fishery of the Atlantic includ- 
ing a final environmental impact state- 
ment, regulatory impact review, initial 
regulatory flexibility analysis, and so- 
cial impact assessment/fishery impact 
statement, 308 p. SAFMC, Charleston, 
SC. [Available at website]. 
