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Fishery Bulletin 11 5(4) 
(41-27°S) and a third, ranging from 27°S and 20°S, 
is known as the “Brazilian Southeastern Bight stock” 
(Carvalho and Gastello, 2013), Different methods have 
been used to identify the 3 stocks: to distinguish the 
patagonic from the bonaerense, Hansen (1994) used 
growth rates, size-weight relationships and length 
at first maturation; Gastello and Gastello (2003) com¬ 
pared larval growth and length at first feeding from 
southeastern and southern Brazil; and Carvalho and 
Gastello (2013) analyzed size and age composition and 
length-at-age data and concluded that anchovies from 
the Santa Marta Region (30-27°S) should be consid¬ 
ered as a part of the bonaerense stock. Although the 
parameters used cannot reveal the genetic discreteness 
of these stocks, they are still powerful tools for stock 
identification purposes (Begg, 2005). 
No study dedicated specifically to variation in egg 
size of the Argentine anchoita has been conducted in 
the southeastern Brazilian Bight (SBB; roughly be¬ 
tween 22°S and 28°S). A few studies have focused 
off the southern coast of Brazil, and the coasts of 
Uruguay and Argentina (Ciechomski, 1973; Phon¬ 
ier, 1984), but they cover only the bonaerense stock. 
Therefore, our objective was to evaluate seasonal and 
regional variability in the size of eggs of Argentine an¬ 
choita in the SBB, and to consider factors that may 
cause such variation. 
Materials and methods 
Study area 
The Brazil Current flows southward along the continen¬ 
tal slope of the SBB (Silveira et al., 2000) transporting 
warm and saline Tropical Water in the upper mixed 
layer and cold South Atlantic Central Water (SACW) at 
the pycnocline. An additional water mass exists in the 
neritic zone, the warm Coastal Water, with lower salin¬ 
ity than the Tropical Water (Castro Filho and Miranda, 
1998). Except for some coastal areas that are under 
the influence of waters flowing from large embayments, 
such as Guanabara Bay in the state of Rio de Janeiro, 
oligotrophic conditions prevail in the study area owing 
to the dominance of Tropical Water in the upper layers, 
and oceanic nutrients trapped within the SACW (Lopes 
et al, 2006). 
The intermittent coastal upwelling off Cape Frio 
is an important process that brings the nutrient-rich 
SACW into the euphotic zone (Valentin et ah, 1987). 
These SACW intrusions vary seasonally, advancing 
toward the coast during spring and summer and re¬ 
treating toward the shelf break in the autumn and 
winter (Cerda and Castro, 2014). Another physical pro¬ 
cess that fertilizes the euphotic zone occurs during the 
winter, when subantarctic and the Plata River Plume 
waters are driven northward by southerly winds from 
the continental shelf of Argentina and Uruguay into 
most of the inner shelf in the south of Brazil and even 
the SBB (Brandini 1990; Stevenson et al., 1998; Piola 
et al., 2000; Gaeta and Brandini, 2006; Piola et ah, 
2008a; Piola et ah, 2008b). 
To address the possible role of spatial (regional) 
and temporal (seasonal) variation in egg size of Argen¬ 
tine anchoita, we used data collected from 2 different 
sets of research cruises: for the regional variation, the 
study area comprised most of the SBB, between Cape 
Frio, in the state of Rio de Janeiro, and Cape Santa 
Marta Grande, in the state of Santa Catarina (roughly 
between 23°S and 28°S). For the seasonal variation, 
the study was carried in the northern part of the SBB, 
from off Cape Sao Tome (22 9 S) to Sao Sebastian Island 
(24 S S), in the state of Sao Paulo during the summer 
and winter of 2001 and 2002 (Fig. 1). 
In situ data 
To assess the seasonal variation in egg size of Argen¬ 
tine anchoita, we took advantage of biotic and abiotic 
data obtained from a set of 4 oceanographic cruises 
carried out during the summer and winter of 2001 and 
2002. During both seasons of 2001, only one transect 
was performed in the Cape Frio region, but some sam¬ 
pling stations were sampled twice. Summer of 2002 
covered 14 transects and winter of 2002 included 13 
transects (Table 1, Fig. 1). 
In order to address patterns in the spatial variation 
in egg size of Argentine anchoita, data were obtained 
from another set of cruises conducted during the sum¬ 
mers over 5 years (1975, 1988, 1990, 1991, and 1993; 
Table 1) and the SBB was divided into 3 areas: area 
1 from Cape Sao Tome to Sao Sebastian Island; area 
2 from Sao Sebasliao Island to Paranagua Bay; and 
area 3 from Paranagua Bay to Cape Santa Marta 
Grande (Fig. 1). These areas were defined on the fol¬ 
lowing bases: 1) Argentine anchoita stock identification 
as defined by Carvalho and Gastello (2013) (area 3); 
2) oceanographic conditions described by Miranda and 
Katsuragawa (1991) and Mahiques et al. (2004) (area 
1 and area 2); 3) a spawning map obtained by Favero 
et ai. (2017), so that the divisions would not separate 
any important spawning area. 
Temperature and salinity data were obtained from 
Nansen bottles and reversing thermometers in 1975 
and 1988. In the other 3 years, a conductivity, tem¬ 
perature, and depth (CTD) profiler, an SBE 91 Tplus 1 
(Sea-Bird Scientific, Bellevue, WA), was used to collect 
this information. 
As described by Smith and Richardson (1977), a 
bongo net with a 0.61-m diameter mouth opening 
was used to sample ichthyoplankton. It was equipped 
with paired cylindrical-conical 0.333-mm and 0.505- 
mm mesh-size nets and with a flowmeter attached 
at the center of the mouth opening of each net in or¬ 
der to measure the volume of filtered water. The net 
was towed obliquely from the surface to the maxi- 
1 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. 
