Ortega-Garda et ai.: Growth of Nematistius pectoralis in the eastern Pacific 
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Fork length (cm) 
Figure 3 
Collective length-weight relationship of all roosterfish (Nematistius 
pectoralis) examined in this study. Specimens were captured in Baja 
California Sur, Mexico, in 2010-2015 and in Golfo Duke, Costa Rica, 
2013-2014. 
549 DGIs. Reader confidence was reduced for samples 
from fish that ranged from 57 to 86 cm FL, primarily 
because of the narrowing and softening of DGI edges. 
Similarly, for roosterfish >86 cm FL, DGIs were not 
easily differentiated and, therefore, these fish were not 
included in the age-estimation portion of our study. An- 
nual growth marks were not observed in sagittal oto- 
liths or in cross sections. 
The estimated parameters of the von Bertalanffy 
growth model are given by area in Table 2. The analy- 
sis of residual sums of squares did not reveal signifi- 
cant differences in growth parameters between Baja 
California Sur and Costa Rica (P>0.05). Therefore, 
the data for both locations was combined into a single 
growth model (Fig. 4). Estimates of growth parameters 
indicate that roosterfish grow rapidly during the first 
year of life, attaining a size of approximately 60-70 cm 
FL within the first year (40% of L„). 
Discussion 
Our study provides the first estimates of age and 
growth for the roosterfish, a species that supports a 
substantial recreational fishery throughout the east- 
ern Pacific Ocean. The growth estimates presented 
here indicate that roosterfish grow at a rapid rate and 
that they may reach up to 60-70 cm FL 
(40% of L^) during the first year of life. 
Accelerated growth in the first year of 
life has been reported for other warm- 
water pelagic species, such as the cobia 
(Rachycentron canadum', Franks et ah, 
1999), dolphinfish (Coryphaena hippu- 
rus; Schwenke and Buckel, 2008), blue 
marlin (Makaira nigricans', Prince et ah, 
1991), and sailfish (Istiophorus platyp- 
terus', Alvarado-Castillo and Felix-Uraga, 
1996). As hypothesized previously, rapid 
early growth is likely advantageous for 
survival because it is linked to swimming 
speed, foraging success, and predation 
(Prince et ah, 1991). Although field vali- 
dation is necessary, our work provides an 
initial hypothesis regarding the growth 
of this valuable eastern Pacific Ocean 
species and increases scientific knowl- 
edge of this poorly known species. 
Samples of roosterfish were obtained 
primarily from recreational fisheries that 
operate seasonally throughout Baja Cali- 
fornia Sur and Central America. Because 
roosterfish are typically released in most 
of these recreational fisheries, acquisition 
of samples was challenging; specimens 
from smaller size classes (<50 cm FL) 
proved to be especially difficult to obtain. 
In addition, because larger individuals 
are particularly prized in the catch-and- 
release fisheries, guides and captains 
rarely harvest specimens >100 cm FL, a tendency that 
further inhibited the collection of larger individuals for 
our study. 
Length-weight relationships 
The estimated b values (Table 1) were within the nor- 
mal, expected range for fish (6=2. 5-3. 5) (Froese, 2006). 
Bagenal and Tesch (1978) suggested that when the 
Table 2 
Parameter values from the von Bertalanffy growth 
model for roosterfish (Nematistius pectoralis) captured 
in Baja California Sur (BCS), Mexico, and Golfo Duke, 
Costa Rica (CR), during 2010-2015: average maximum 
length (L„), measured as fork length in centimeters, in- 
dividual growth coefficient (k), and the hypothetical age 
when the length is equal to 0 (Iq), measured in years. 
Area 
k 
^0 
BCS 
166.90 
0.48 
-0.02 
CR 
171.72 
0.47 
-0.08 
Areas combined 
163.77 
0.47 
-0.08 
