118 
world (Eschmeyer et al., 1983). To a lesser degree, the 
roosterfish also supports small-scale artisanal fisher- 
ies along the coast of Baja California Sur and Central 
America; however, because of its limited market value, 
it is not typically the primary target of such fishing 
operations (Lindner, 1947; Niem, 1995). 
Despite the ecological and economic importance of 
roosterfish, very few scientific studies have focused on 
this species and basic biological parameters remain 
largely unknown. In particular, questions pertaining 
to age and growth, natural mortality, longevity, and 
reproductive biology remain unanswered. These para- 
meters are essential for fisheries management and 
form the basis for most stock assessment models (Gold- 
man, 2005). This information is also essential for un- 
derstanding other biological and population traits such 
as productivity, yield per recruit, predator and prey dy- 
namics, and habitat requirements (DeVries and Erie, 
1996; Campana, 2001; Robinson and Motta, 2002). 
Given the importance of this species to regional fish- 
eries off the coast of Baja California Sur and Central 
America, we estimated age and growth in our study 
by counting presumed daily growth increments (DGIs) 
within the sagittal otolith. The results of our study pro- 
vide the first estimates of growth for this species and 
allow intraspecific comparisons of growth between 2 
geographically distinct locations along the range of the 
roosterfish in the eastern Pacific Ocean. 
Materials and methods 
Collection details 
From 2010 through 2015, roosterfish specimens were 
obtained from the sportfishing fieet in Cabo San Lu- 
cas and La Paz, Baja California Sur, Mexico. Similarly, 
from 2013 through 2014, specimens were collected from 
commercial and recreational fleets that operated out of 
the Golfo Duke, Costa Rica. Each specimen was mea- 
sured to determine fork length (EL) to the nearest 0.1 
cm and weighed to the nearest 0.01 kg. Sex was deter- 
mined by visual inspection of the gonads, and, when 
possible, sagittal otolith pairs were removed, cleaned, 
and stored dry. 
Length-weight relationships 
Length-weight relationships (LWRs) were estimated by 
using the allometric equation: 
W = aFLb, 
where W = the weight; and 
a and b = the intercept and the slope of the regression 
line, respectively (Ricker, 1975). 
As with previous works, we assumed that, when b 
was equal to 3, the relationship was considered to be 
isometric (Sangun et al., 2007). Similarly, b values ?*3 
were associated with allometric growth (Froese, 2006). 
Estimates of LWRs were calculated independently for 
Fishery Bulletin 115(1) 
both sex (males and females) and location (Baja Cali- 
fornia Sur and Golfo Duke) and compared by using a i! 
Student’s t-test (Zar, 2010). A Student’s t-test was also | 
used to evaluate whether b values were significantly ■ 
different from the null hypothesis for isometric growth ] 
{Hq. 6=3) (Sangun et al., 2007; Zar, 2010). 
! 
Preparation and analysis of otoliths i 
1 
Preparation of otoliths followed closely the protocol de- 5 
scribed by Secor et al., 1992. Briefly, the right otolith of j 
each specimen was embedded in crystal polyester resin ! 
and allowed to harden and dry for a 24-h period. We 
created transverse sections (0.6 mm) through each oto- ' 
lith that included the core (Fig. 1) by using an IsoMet i 
Low Speed Saw^ (model 11-1280-160; Buehler, Lake j 
Bluff, IL) equipped with a diamond watering blade (se- 
ries 15HC, Buehler). Because otolith increments (e.g., 
daily or annual) of many perciform fish species are not 
deposited in the sagittal plane, the transverse or the 
frontal planes typically are used for assessing DGIs 
(Secor et al., 1992). 
Most otoliths need some form of preparation before 
their microstructure can be accurately determined; 
therefore, a polishing procedure was used to remove 
material, expose the core region, and reveal the pre- 
sumed DGIs (Secor et al., 1992). To clearly define 
DGIs and facilitate readings, transversal sections were 
mounted on histological slides with Cytoseal mounting 
medium (Thermo Fisher Scientific, Waltham, MA) and 
hand polished with a series of micrometric sandpaper 
of decreasing grit size (15-3 pm, Diamond Lapping 
Film disc; Buehler). For finishing, sections were pol- 
ished with 0.3-pm MicroPolish alumina (Buehler) and 
0.3-pm MicroCloth micrometric sandpaper (Buehler). 
Two readers independently counted presumed DGIs 
of prepared otolith sections without prior knowledge 
of fish length and weight. Readers counted DGIs on 
transverse sections by using a microscope with trans- 
mitted light (40-100x). Daily growth increments were 
counted from the core toward the dorsal edge of the 
otolith along the same transect (Fig. 1). 
The consistency or concordance of counts between 
readers was estimated by using a coefficient of varia- 
tion (CV) (Chang, 1982): 
where CVj 
R 
CVi = 100%x ^^^=^ , (1) 
the age precision estimate for the jth fish; 
the ith age determination of the jth fish; 
the mean age estimate of the jth fish; and 
the number of times each fish was aged. 
Lengths at age derived from otolith readings were 
used to estimate the 3 parameters of the standard von 
Bertalanffy growth model: 
^ Mention of trade names or commercial companies is for iden- 
tification purposes only and does not imply endorsement by 
the National Marine Fisheries Service, NOAA. 
