Favero et al: Variation in egg size of Engraulis anchoita in the southeastern Brazilian Bight 
527 
49°W 48°W 47°W 46°W 45 = W 44"W 43”W 42’W 41'W 40“W 49"W 48"W 47*W 46°W 45"W 44°W 43"W 42°W 41°W 40"W 
22°S 
23"S 
24°S 
25°S 
26°S 
27’S 
28'S 
29°S 
49“W 48°W 47°W 46°W 45"W 44"W 43"W 42"W 41*W 40"W 
Jan-93 1 (°C) 
49°W 48‘W 47°W 46"W 45”W 44'W 43”W 42"W 4TW 40"W 
49-W 48°W 47'W 46°W 45°W 44"W 43"W 42"W 41*W 40°W 
Figure 6 
Horizontal distribution of temperature (°C) at a 10-m depth from in situ measurements 
taken during cruises conducted in the southeastern Brazilian Bight in 1975, 1988, 1990, 
1991, and 1993. 
the highest stomach fullness values were found at sta¬ 
tions close to the surface salinity front (Padovani et 
al., 2011). 
The satellite images in Figures 2 and 3 probably in¬ 
dicate the flow of Plata plume water carrying chloro¬ 
phyll from the south to the north during the winter on 
the inner shelf. This flow could be guiding the migra¬ 
tion of the Argentine anchoita northward, which also 
happens during the winter. Because the eggs collected 
during the winter are larger than those from the sum¬ 
mer, one possibility for this difference is that larger 
adults coming from the south would be spawning in or 
closer to the study area in winter, but no conclusion 
can be made with the data from this study because 
there have been no studies in which the length and age 
structure of Argentine anchoita have been compared 
during different seasons in the SBB, nor have there 
been any genetic studies to differentiate the stocks of 
this species. 
Seasonal variation in egg size may also be an 
adaptive response to the changes in the abiotic con¬ 
ditions that the eggs will encounter. An increase in 
temperature decreases the incubation period (time 
from fertilization to hatching), and a decrease in egg 
size decreases the incubation period (Wootton, 1990). 
In our results, temperature and salinity were high¬ 
er during the summer than during winter for both 
years and, as expected, the eggs were smaller. Small¬ 
est eggs in populations spawning during the summer 
were also observed in the Atlantic herring (Clupea 
