Abstract — Squaretail coralgrouper 
(Plectropomus areolatus) were cap- 
tured and tagged at a fish spawning 
aggregation (FSA) site with conven- 
tional and acoustic tags to assess 
their vulnerability to fishing and 
spatial dynamics during reproductive 
periods. Males outnumbered females 
in catch and, on average, were larger 
than females. Findings revealed a 
high vulnerability to fishing, par- 
ticularly during reproductive peri- 
ods, and most fish were recaptured 
within the 5-month spawning season 
and within 10-12 km of the aggrega- 
tion site. Individual and sex-specific 
variability in movement to, and resi- 
dency times at, the FSA site indicates 
that individual monthly spawning 
aggregations represent subsets of the 
total reproductive population. Some 
individuals appeared to move along a 
common migratory corridor to reach 
the FSA site. Sex-specific behavioral 
differences, particularly longer resi- 
dency times, appear to increase the 
vulnerability of reproductively active 
males to fishing, particularly within 
a FSA, which could reduce reproduc- 
tive output. Both fishery-dependent 
and fishery-independent data indi- 
cate that only males were present 
within the first month of aggrega- 
tion. The combined results indicate 
that reproductively active P. areolatus 
are highly vulnerable to fishing and 
that FSAs and migratory corridors of 
reproductively active fish should be 
incorporated into marine protected 
areas. The capture of P. areolatus 
during reproductive periods should 
be restricted as part of a comprehen- 
sive management strategy. 
Manuscript submitted 1 October 2007. 
Manuscript accepted 8 February 2008. 
Fish. Bull. 106:194-203 (2008). 
The views and opinions expressed or 
implied in this article are those of the 
author and do not necessarily reflect 
the position of the National Marine 
Fisheries Service, NOAA. 
The vulnerability of reproductively active 
squaretail coralgrouper 
( Plectropomus areolatus ) to fishing 
Kevin L. Rhodes (contact author ) 1 
Mark H. Tupper 2 
Email address for Kevin L. Rhodes: klrhodes_grouper@sbcglobal.net 
1 The University of Hawaii at Hilo, College of Agriculture 
Forestry and Natural Resource Management 
200 W. Kawili St. 
Hilo, Hawaii 96720 
2 WorldFish Center 
PO Box 500 GPO 
10670 Penang, Malaysia 
Epinepheline serranids (groupers, 
hinds, lyretails) that form fish spawn- 
ing aggregations (FSAs) are among 
the most vulnerable coral reef fishes 
to overexploitation (Coleman et ah, 
2000; Sadovy and Domeier, 2005). 
Indeed, 20 of 162 epinepheline ser- 
ranids (hereafter, serranids), includ- 
ing species that form FSAs, are now 
considered vulnerable or endangered 
according to IUCN Red List criteria. 
Among those listed as vulnerable is 
the squaretail coralgrouper ( Plectro- 
pomus areolatus ) (Riippell, 1830) that 
forms temporally and spatially pre- 
dictable FSAs, often numbering in the 
100s to 1000s of individuals. These 
traits contribute to the targeting of P. 
areolatus by local and foreign commer- 
cial fisheries, including the Southeast 
Asia-based live reef food fish fishery 
(Sadovy et al., 2003). When both FSAs 
and reproductively active individu- 
als are targeted enroute to spawning 
sites, reproductive populations may 
experience population-level changes 
that affect reproductive output, includ- 
ing skewed aggregation sex ratios fol- 
lowing sexual selection (e.g., Koenig et 
al., 1996), size reductions (e.g., Beets 
and Friedlander, 1998), changes in 
genetic diversity (Chapman et al., 
1999), and loss or decline in FSA (e.g., 
Sadovy and Domeier, 2005). With few 
exceptions, FSA fishing is unsustain- 
able under anything more than light 
fishing pressure, such as that char- 
acteristic of limited subsistence-level 
fishing (Sadovy and Domeier, 2005). 
Reports of grouper FSA loss continue 
to increase worldwide (e.g., Matos- 
Caraballo et al., 2006; Aguilar-Perera, 
2007) and increased fishing mortality 
at FSAs is implicated in local fishery 
declines (Sadovy and Domeier, 2005). 
Among measures recently touted to 
protect FSAs and reproductive popu- 
lations from overfishing are marine 
protected areas (MPAs). However, 
few reports show the effectiveness of 
MPAs in limiting or preventing FSA 
loss, or in improving population-level 
abundance (Nemeth, 2005). Moreover, 
most existing FSA-based MPAs are 
small and likely leave reproductively 
active individuals vulnerable to fish- 
ing, such as some reproductively active 
serranids that appear to use common 
migratory corridors to reach FSAs, 
where they can be fished before they 
spawn (Nemeth et al., 2007; Starr et 
al., 2007). Migratory corridors and 
the dangers of overexploitation when 
corridors are left unprotected are 
recorded for a number of fishes, such 
as gadids (e.g., Rose, 1993). To design 
effective management for reproduc- 
tive populations of serranids such as 
squaretail coralgrouper, areas of high 
fishing vulnerability must be identi- 
fied, including FSA sites, migratory 
corridors, and other areas where fish 
may concentrate during reproductive 
periods. 
Within the tropical Pacific, only Pa- 
lau and Pohnpei have developed long- 
term management protocols at the 
national level specifically to protect 
