Karlou-Riga et a 1 .: Sex change and oscillating growth pattern of Spicara smaris in the Saronikos Gulf (Greece) 
349 
Gulf of Corinth 
Greece 
Legend 
• trawler sampling sites 
★ beach seine sampling sites 
u Piraeus 
★ 
Salamina 
• *• * 
* Aegina 
★ • 
Saronikos Gulf 
0 5 10 
Figure 1 
Map of the Saronikos Gulf in Greece showing sites where picarel (Spicara 
smaris) were sampled by trawler (black circles) or by beach seine (stars) from 
September 1998 through August 1999. 
dally important. The ratio of picarel production to the 
total production for the period between 1990 and 2009 
varied from 3.91 to 8.32 (sea fisheries statistics, Na¬ 
tional Statistical Service of Greece, available from web¬ 
site). It is caught by beach seines, trawlers, nets, and 
purse seines, but the catch by beach seines accounts 
for almost half of the catch by the other gears. Picarel 
represents the major target species of beach seine ves¬ 
sels; other congeneric species do not significantly con¬ 
tribute to the beach seine catch (Karlou-Riga et al., 
1997; Papaconstantinou et al., 2007). 
The picarel is a protogynous species and presents 
sexual dimorphism (Zei, 1950; Salekhova, 1979; White- 
head et al., 1986). Protogyny in picarel has also been 
confirmed histologically. During sexual transition, 
ovarian tissue degenerates and testicular tissue pro¬ 
liferates (Mitcheson and Liu, 2008). The fish occur in 
schools, except during time of breeding (Tsangridis and 
Filippousis, 1992). According to Harmelin and Harrne- 
lin-Vivien (1976), each nest is guarded by a brightly 
colored male. After incubation, the males lose their col¬ 
oration and swim in schools to feeding areas. Regard¬ 
ing the age and growth of picarel in the Mediterranean 
Sea, the literature is quite extensive (Salekhova, 1979; 
Tsangridis and Filippousis, 1989, 1991, 1992; Ismen, 
1995; Vidalis and Tsimenidis, 1996; Rizkalla, 1997; 
Duldip et al., 2003). Despite the number of publica¬ 
tions, discrepancies do exist in both age determination 
and growth rates. It is noted, however, that Denaxa et 
al. (2014), who studied ages of picarel in Greek waters 
by means of otolith microstructure, gave important in¬ 
formation on the first annulus formation. 
Oscillating growth rates have been observed to influ¬ 
ence sex change, but have never been studied in detail 
(Tsangridis and Filippousis, 1992). However, they have 
been recognized as the cause of discrepant length-at- 
age estimates (Vidalis and Tsimenidis, 1996). Spawn¬ 
ing seasonality and body sizes at sex change have, also, 
been identified as important in developing manage¬ 
ment plans for sustainable extraction of sequentially 
hermaphroditic species (DeMartini et al., 2011). 
Here we attempt to validate ages or to use alter¬ 
native ways to assign the specimen to age groups, as 
well as to address species growth on the basis of pi¬ 
carel sex change. Sex selection was also studied, and 
the presence of early maturing males (EMMs) was ex¬ 
amined (Allsop and West, 2004a). Finally, the length 
and age at median (50%) female-to-male sex change 
were investigated to see whether they are as invariant 
as predicted by Charnov and Skuladottir (2000) and 
supported by Allsop and West (2003a). We consider the 
present work innovative, since both these alternative 
ways of age validation, as well as the growth study of 
a protogynous species examined within the sex change 
framework, are seldom found in the literature. 
Materials and methods 
Samples of picarel were collected monthly with a beach 
seine in the Saronikos Gulf (Fig. 1) during the period 
from September 1998 through August 1999 (Table 1). 
Because of bad weather conditions in November and 
December, a chartered bottom trawler was used in- 
