352 
Fishery Bulletin 11 6(3-4) 
The presence of EMMs was examined in an effort to 
determine whether the species is diandrous and, if so, 
to estimate the relative proportion of fish maturing di¬ 
rectly or early into males. According to Allsop and West 
(2004a), the proportion of EMMs is calculated by us¬ 
ing the logistic parameters derived from the number of 
males in each length class at the 5 th percentile of the 
population length distribution according to the follow¬ 
ing equation: 
(a+bx) 
Proportion male (sex ratio) = 
1 + e 
(a+bx) ’ 
(3) 
where 
= the intercept of the logistic regression; 
= the slope; and 
- the length at the 5 th percentile. 
According to Allsop and West (2004a), the sex ratio 
at the 5 th percentile is chosen because it is sufficiently 
close to the lower end of the population length distribu¬ 
tion, to ensure that the males present are EMMs and 
not the product of sex change and so as to minimize 
the error inherent in measuring and determining the 
sex of these smaller-size individuals. 
Classic and oscillated VBGF curves were fitted to 
the data by using a script in the fsa package, vers. 
0.8.20 (Ogle, 2018) of statistical software R, vers. 
3.4.2 (R Core Team, 2017). Model diagnostics, includ¬ 
ing residual versus predicted plots and histograms 
were used for evaluating the goodness of fit of test¬ 
ed models. The linear correlation among study vari¬ 
ables was examined by using the Pearson test. Ad¬ 
ditional statistical procedures were performed using 
Statgraphics Plus 5 software (Statgraphics 
Technologies, Inc., The Plains, VA). PRIM¬ 
ER 5 software (PRIMER-E, Auckland, New 
Zealand; Carr, 1997; Clarke and Gorley, 
2001) was also used for obtaining the sim¬ 
ilarity index and for cluster analysis. All 
the statistical inferences were based on 
the 0.05-significance level. 
Results 
From a total of 6458 specimens collected, 
measuring 4.3 to 20.7 cm TL, 2925 fish 
were retained for further measurements, 
from which 1694 otoliths were removed for 
age determination (Table 1). In the present 
study, the maximum length (L max ) of males 
and females was 20.7 and 19.7 cm TL, re¬ 
spectively. Specimens of undetermined sex 
ranged between 4.3 and 10.6 cm TL. Infor¬ 
mation on L max values for picarel as drawn 
from the literature is given in the Supple¬ 
mentary Table. 
Monthly length frequencies were con¬ 
structed (Suppl. Fig. 1) to follow the pro¬ 
gression of smaller fish modal lengths (4.5- 
8.0 cm TL) during the year, in order to examine an¬ 
nuli formation on the otoliths. The smaller specimens, 
which apparently belonged to the cohort of that year, 
were caught in July. The same cohort was followed in 
August, September, and October. The respective oto¬ 
liths did not show any distinct hyaline zone (Suppl. 
Fig. 2A), which, however, started to be shown, with 
the progression of the same cohort, and in January 
samples. This hyaline margin increased progressively 
in successive months, and in some of the July otoliths, 
the hyaline zone, which was interpreted as the 1 st an¬ 
nulus, appeared complete (Suppl. Fig. 2B). The succes¬ 
sive hyaline zones were interpreted as annuli mainly 
on the basis of the gradual decrease of their width and 
their formation at progressively greater distances from 
the core (Suppl. Fig. 2C). It seems that the 4 th , the 5 th , 
and the 6 th annuli appear very close to each other, and 
the contrast between the opaque and hyaline area is in 
general not strong. Despite this difficulty, the study of 
the otolith edge showed seasonality; the percentage of 
hyaline areas on the edge attained the highest value 
in June and the lowest in October (Suppl. Fig. 3). The 
oldest fish were found to have 6 annuli. 
The MI widths next to the 1 st (Mil), the 2 nd (MI2), 
the 3 rd (MI3), and the 4 th (MI4) annuli showed a 
seasonal progression (one-way analysis of variance, 
P< 0.05, Mil: df=486, MI2: df=241, MIS: df=157, MI4: 
df=79). The lowest values of Mis were found in October 
and the highest values during May-June, indicating 
that the annuli are completed between June and Oc¬ 
tober (Fig. 3). 
