Macchi et ai.: Maternal effects on fecundity and egg quality of Merluccius hubbsi 
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25 30 35 40 45 50 55 60 65 70 75 80 
Total length (cm) 
Figure 5 
Relationship between proportion of females with empty 
stomachs and female size obtained for the Patagonian 
stock of Argentine Hake ( Merluccius hubbsi), which was 
sampled in waters off the province of Chubut in Argen- 
tina during the peak spawning season in January 2010 
and 2011. 
ductive potential because of the role that lipids serve 
in reserving energy (Marshall et al., 1999). Support- 
ing this idea, Leonarduzzi et al. (2012) analyzed the 
proximal composition of different tissues in Argentine 
Hake females and showed that the best morphological 
index for the somatic condition in Argentine Hake is 
the HSI — a finding that agrees with results obtained 
for other fish species (Alonso-Fernandez, 2011). There- 
fore, it is reasonable to assume that reproductive po- 
tential of Argentine Hake may be affected by the liver 
condition of spawning females. 
Positive relationships between DW and the vari- 
ables of TL, GW, and age were observed for Argentine 
Hake — results that coincide with previous studies of 
this species (Macchi et al., 2006), and for European 
Hake (Mehault et al., 2010). Moreover, the positive 
relationship between DW and fecundity indicates 
that larger females of Argentine Hake invest energy 
in both the quantity and quality of the oocytes that 
they produce. The increases observed in oocyte mass 
with female size for Argentine Hake agrees with the 
hypothesis of a maternal effect on the spawning qual- 
ity of this species. Argentine Hake also showed a posi- 
tive relationship between DW and female condition, 
expressed by the HSI. This result supports the idea 
that the size and composition of oocytes depend on the 
maternal nutritional state and are particularly associ- 
ated with liver weight (Marteinsdottir and Begg, 2002). 
The difference observed between the size of the oil 
droplets in hydrated oocytes of first-time spawners (<40 
cm TL) and old females (>70 cm TL) also reflected the 
maternal contribution to reproductive success. Oocytes 
of old individuals were characterized by oil globules 
that were larger than the oil globules of young 
spawners, indicating that more lipids were stored 
in the eggs of larger females. In other fish species 
that have been studied (e.g., Sebastes spp.), older 
females produced eggs with larger oil globules, 
which result in larvae with better chance of sur- 
vival (Berkeley et al., 2004; Sogard et al., 2008). 
Similar conclusions indicating that fatty acids are 
essential for egg composition and reproductive 
success were drawn with species maintained in 
captivity and fed with different concentrations of 
lipids (Watanabe et al., 1984; Fernandez-Palacios 
et al., 1995; Sewall and Rodgveller, 2009). Fur- 
thermore, the positive relationship observed in 
Argentine Hake in this study between the sizes of 
eggs from plankton samples and diameters of their 
oil droplets indicates that larger eggs contain a 
higher amount of lipids than do smaller eggs, sup- 
porting the idea that bigger oocytes are of better 
quality. 
The decrease in frequency of empty stomachs 
with the size of the Argentine Hake females is 
evidence that feeding activity is higher in larger 
individuals. In addition, this result supports the 
hypothesis of continuous feeding during breed- 
ing season for other hake species (Dominguez-Petit 
and Saborido-Rey, 2010). The relationship between the 
percentage of individuals with empty stomachs and TL 
was more evident in females <55 cm TL; at this size 
range, the slope of the equation was more pronounced. 
This break in the regression model is similar to the 
break previously found for the relationship of oocyte 
weight to female size in Argentine Hake (Macchi et al., 
2006). Those authors reported that differences between 
egg mass and female size can be observed mainly in 
young spawners (<55 cm TL) because, in females >55 
cm TL, the slope of the model decreased, as a conse- 
quence of the high variability in oocyte weight. 
Female condition and the quality of eggs produced 
by Argentine Hake may be associated with the feeding 
range of this species. It is possible that larger individu- 
als would be capable of swimming longer distances as 
they search for food in deeper waters, where it is com- 
mon to find great concentrations of squid ( Ilex argenti- 
nus ) in the austral summer. This squid species is con- 
sidered the most important prey for larger individuals 
of Argentine Hake in the Patagonian area (Angelescu 
and Prenski, 1987). A recent study described an off- 
shore spawning group of Argentine Hake in Patagonian 
waters in January that was characterized by a high 
proportion of females >55 cm TL and older than 5 years 
(Macchi et al., 2010). The selection of squid for food by 
larger females may be advantageous for spawning, if 
the high concentration of fatty acids detected in this 
mollusk is taken into account (Watanabe et al., 1984). 
Therefore, studies on Argentine Hake diet and the ef- 
fect of diet composition on egg quality are needed. In 
particular, further information is required about lipid, 
fatty acids, proteins, and ascorbic acid content, all rel- 
