328 
Fishery Bulletin 111(4) 
The relationships of BF to TL obtained in 2010 and 
2011 were compared on the basis of overlapping length 
ranges of the females (32-83 cm TL) with analysis of 
covariance on the log-transformed data (Draper and 
Smith, 1981). After comparison, the relationships of 
BF and RF to TL, gutted weight, age, HSI, and Kn ob- 
tained from samples and data collected in both years 
were described through the use of simple regression 
analysis. 
Egg quality 
A sample of 100 hydrated oocytes was removed from 
one ovary of each female selected for estimation of fe- 
cundity, rinsed in distilled water to remove formalde- 
hyde remnants, dried for 24 h at 60°C, and weighed 
to the nearest 0.1 mg. The DW of each of these sam- 
ples was considered an index of egg quality for the 
spawning females of Argentine Hake collected dur- 
ing the 2 research cruises because, in general, dry 
mass is associated with the quantity of yolk reserves 
stored in oocytes (Macchi et ah, 2006; Mehault et al., 
2010). The relationships between DW and the differ- 
ent morphophysiological variables (TL, GW, age, HSI, 
and Kn), on the basis of length, weight, or organ-body 
weight ratios, were evaluated with simple regression 
analysis as were the fecundity data. Moreover, the re- 
lationships between DW and the number of oocytes 
spawned by batch (BF) and by unit of female weight 
(RF) were analyzed. 
To determine the effect of each maternal attribute 
on fecundity and egg quality and to establish which 
of these predictor variables had more influence on the 
number and quality of the oocytes, multiple regres- 
sion analyses of BF and DW in relation to morpho- 
physiological variables were carried out with the for- 
ward stepwise method. In the case of the regression 
model for BF, the data showed heteroscedasticity and 
were log-transformed. Colinearity between variables 
was analyzed to include in the model only those vari- 
ables that were uncorrelated. All statistical analyses 
were conducted with R software (R Development Core 
Team, 2010). 
Another variable possibly associated with egg qual- 
ity is the size of the oil droplet in mature eggs, be- 
cause it functions as an energy source for larvae 
(Wiegand, 1996; Nocillado et al., 2000; Rodgveller et 
al., 2012). For this reason, the diameters of oil drop- 
lets in hydrated oocytes were measured in samples of 
Argentine Hake females collected in January 2011. 
Samples collected in 2010 were not used, because 
hydrated oocytes from this year were in bad condi- 
tion as a consequence of long-term preservation in 
formalin solution. To analyze possible differences be- 
tween old and young females, 2 length groups were 
considered for this analysis: individuals <40 cm TL 
(n=12) and >70 cm TL (n=17). Most adult female Ar- 
gentine Hake <40 cm TL are 2-3 years old and con- 
sidered first-time spawners for the Patagonian stock 
of this species (Otero et al., 1986). First-time spawn- 
ers are thought to produce eggs of lower quality than 
the eggs of older females, as Trippel (1998) found 
for Atlantic Cod (Gadus morhua). Hydrated oocytes 
from each of the 2 length groups of females (n = 641 
and 1000 oocytes) were sampled and the diameters 
of the oil droplets were measured to the nearest 0.01 
pm with a Carl Zeiss 3 stereomicroscope equipped with 
AxioVision 4.6 software (Carl Zeiss Microscopy, Jena, 
Germany). The mean diameters obtained for each size 
group were compared with a t-test. 
Because the size of hydrated oocytes in the ovaries 
may be influenced by the degree of hydration, we used 
spawned eggs to analyze the relationship between egg 
diameter and size of the oil droplet. Therefore, egg di- 
ameters and sizes of oil droplets were measured from 
Argentine Hake eggs collected in plankton samples, 
from oblique tows conducted with a bongo net (mesh 
sizes: 300 and 500 pm) in the research survey of Janu- 
ary 2010. Samples were fixed in 5% formalin, and lat- 
er Argentine Hake eggs in early developmental stages 
were sorted and rinsed in distilled water. Argentine 
Hake eggs were identified according to Ehrlich (1998). 
Egg diameter and size of the oil droplet (n=102) were 
measured to the nearest 0.01 pm, as was done for hy- 
drated oocytes, and the relationship between them was 
evaluated with simple regression analysis. 
Feeding activity during spawning 
Stomach fullness of Argentine Hake females during 
spawning was analyzed to find a possible relationship 
between feeding activity and the size of spawners. 
Information on stomach content obtained from all 
adult females sampled in the reproductive area 
during the 2 research cruises in January 2010 and 
2011 (n=2091) was considered in this study. Individuals 
with everted stomachs as a consequence of pressure 
changes during capture were not used in this analysis. 
A gross scale of 4 stages was employed to classify the 
degree of stomach fullness: 0=empty, l=few contents 
(<25% full), 2=moderate contents (25-75% full) and 
3=full stomach (Prenski and Angelescu 4 ). The frequency 
distribution of each stomach stage by length class was 
considered in this analysis, but only stage 0 was em- 
ployed to determine differences in feeding activity. The 
relationship between the proportion of empty stomachs 
and female size was described with simple regression 
analysis. 
3 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. 
4 Prenski, L. B., and V. Angelescu. 1993. Ecologia trofica de 
la merluza comun ( Merluccius hubbsi ) del Mar Argentino. 
Parte 3. Consumo anual de alimento a nivel poblacional y su 
relacion con la explotacion de las pesquerfas multiespeci'ficas. 
INIDEP Documento Cienti'fico No. 1, 118 p. [Available from 
INIDEP, Paseo Victoria Ocampo Nro. 1, B76G2HSA Mar del 
Plata, Argentina.! 
